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Jun
09

Emmure- Solar Flare Homicide (Lyrics)

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Lyrics to “Solar Flare Homicide” by “Emmure” Please leave feedback, subscribe or follow me on twitter for latest video updates. Twitter: twitter.com Facebook: www.facebook.com
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Jun
08

Paragliding

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Equipment

Wing

Parts of a paraglider

The paraglider wing or canopy is known in aeronautical engineering as a ram-air airfoil, or parafoil. Such wings comprise two layers of fabric which are connected to internal supporting material in such a way as to form a row of cells. By leaving most of the cells open only at the leading edge, incoming air (ram-air pressure) keeps the wing inflated, thus maintaining its shape. When inflated, the wing’s cross-section has the typical teardrop aerofoil shape.

In some modern paragliders (from the 1990s onwards), especially higher performance wings, some of the cells of the leading edge are closed to form a cleaner aerodynamic airfoil. Like the wingtips, these cells are kept inflated by the internal pressure of the wing Wings Infos.

The pilot is supported underneath the wing by a network of lines. The lines are gathered into two sets as left and right risers. The risers collect the lines in rows from front to back in either 3 or 4 rows, distributing load as in a whippletree. The risers are connected to the pilot’s harness by two carabiners.

Paraglider wings typically have an area of 2035 square metres (220380 sq ft) with a span of 812 metres (2639 ft), and weigh 37 kilograms (6.615 lb). Combined weight of wing, harness, reserve, instruments, helmet, etc. is around 1218 kilograms (2640 lb).

The glide ratio of paragliders ranges from 8:1 for recreational wings, to about 11:1 for modern competition models[citation needed]. For comparison, a typical skydiving parachute will achieve about 3:1 glide. A hang glider will achieve about 15:1 glide. An idling (gliding) Cessna 152 will achieve 9:1. Some sailplanes can achieve a glide ratio of up to 72:1.

The speed range of paragliders is typically 2060 kilometres per hour (1237 mph), from stall speed to maximum speed. Beginner wings will be in the lower part of this range, high-performance wings in the upper part of the range. The range for safe flying will be somewhat smaller.

Modern paraglider wings are made of high-performance non-porous fabrics such as OLKS from Gelvenor, with Dyneema/Spectra or Kevlar/Aramid lines.

For storage and carrying, the wing is usually folded into a stuffsack (bag), which can then be stowed in a large backpack along with the harness. For pilots who may not want the added weight or fuss of a backpack, some modern harnesses include the ability to turn the harness inside out such that it becomes a backpack.

Tandem paragliders, designed to carry the pilot and one passenger, are larger but otherwise similar. They usually fly faster with higher trim speeds, are more resistant to collapse, and have a slightly higher sink rate compared to solo paragliders.

Since 2000 Juan Salvadori in Argentina has been exploring a variant wing termed Paramontante that involves some firm beams. In April 2009 Pere Casellas has joined in a collaboration with Juan Salvadori for polishing the paramontante. Laboratori d’envol Paramontante

Harness

Pilot with harness (light blue) doing reverse launch

The pilot is loosely and comfortably buckled into a harness which offers support in both the standing and sitting positions. Modern harnesses are designed to be as comfortable as a lounge chair in the sitting position. Many harnesses even have an adjustable ‘lumbar support’. A reserve parachute is also typically connected to a paragliding harness.

The primary purpose of parachutes (including skydiving canopies) is for descending, as when jumping out of an aircraft or dropping cargo. In contrast, the primary purpose of paragliders is for ascending. Paragliders are categorized as “ascending parachutes” by canopy manufacturers worldwide, and are designed for “free flying” meaning flight without a tether (for an example of tethered flight, see parasailing). However, in areas without high launch points, paragliders may be towed aloft by a ground vehicle or a stationary winch, after which they are released, creating much the same effect as a mountain launch. Such tethered launches can give a paraglider pilot a higher starting point than many mountains do, offering similar opportunities to catch thermals and to remain airborne by “thermaling” and other forms of lift. As free flight, paragliding requires the significant skill and training required for aircraft control, including aeronautical theory, meteorological knowledge and forecasting, personal/emotional safety considerations, adherence to applicable Federal Aviation Regulations (US), and knowledge of equipment care and maintenance.

Instruments

Most pilots use variometers, radios, and, increasingly, GPS units when flying.

Variometer

Vario-altimeter

Birds are highly sensitive to atmospheric pressure, and can tell when they are in rising or sinking air. People can sense the acceleration when they first hit a thermal, but cannot detect the difference between constant rising air and constant sinking air, so turn to technology to help. Modern variometers are capable of detecting rates of climb or sink of 1 cm per second, such is the case of the Flymaster B1 which uses extremely low noise electronics and complex algorithms to detect such minute changes in air pressure.

A variometer indicates climb-rate (or sink-rate) with short audio signals (beeps, which increase in pitch and tempo during ascent, and a droning sound, which gets deeper as the rate of descent increases) and/or a visual display. It also shows altitude: either above takeoff, above sea level, or (at higher altitudes) “flight level.”

The main purpose of a variometer is in helping a pilot find and stay in the “core” of a thermal to maximise height gain and, conversely, to indicate when a pilot is in sinking air and needs to find rising air.

The more advanced variometers have an integrated GPS. This is not only more convenient, but also allows one to record the flight in three dimensions. The track of the flight is digitally signed and stored and can be downloaded after the landing. Digitally signed tracks can be used as proof for record claims, replacing the ‘old’ method of photo documentation.

2m-band radio

Radio

Pilots use radio for training purposes, for communicating with other pilots in the air, particularly when travelling together on cross-country flights, and for reporting the location of landing.

Radios used are PTT (push-to-talk) transceivers, normally operating in or around the FM VHF 2-metre band (144148 MHz). The “2 Meter” band is an amateur radio band, sometimes used for interpersonal communications, and Aviation Frequencies are usually 108MHz to 136MHz. Usually a microphone is incorporated in the helmet, and the PTT switch is either fixed to the outside of the helmet, or strapped to a finger.

GPS

GPS (global positioning system) is a necessary accessory when flying competitions, where it has to be demonstrated that way-points have been correctly passed.

It can also be interesting to view a GPS track of a flight when back on the ground, to analyze flying technique. Computer software is available which allows various different analyses of GPS tracks (e.g. CompeGPS, See You).

Other uses include being able to determine drift due to the prevailing wind when flying at altitude, providing position information to allow restricted airspace to be avoided, and identifying one location for retrieval teams after landing-out in unfamiliar territory.

More recently, the use of GPS data, linked to a computer, has enabled pilots to share 3D tracks of their flights on Google Earth. This fascinating insight allows comparisons between competing pilots to be made in a detailed ‘post-flight’ analysis.

Control

Speedbar mechanism.

Brakes: Controls held in each of the pilot hands connect to the trailing edge of the left and right sides of the wing. These controls are called ‘brakes’ and provide the primary and most general means of control in a paraglider. The brakes are used to adjust speed, to steer (in addition to weight-shift), and flare (during landing).

Weight Shift: In addition to manipulating the brakes, a paraglider pilot must also lean in order to steer properly. Such ‘weight-shifting’ can also be used for more limited steering when brake use is unavailable, such as when under ‘big ears’ (see below). More advanced control techniques may also involve weight-shifting.

Speed Bar: A kind of foot control called the ‘speed bar’ (also ‘accelerator’) attaches to the paragliding harness and connects to the leading edge of the paraglider wing, usually through a system of at least two pulleys (see animation in margin). This control is used to increase speed, and does so by decreasing the wing’s angle of attack. This control is necessary because the brakes can only slow the wing from what is called ‘trim speed’ (no brakes applied). The accelerator is needed to go faster than this.

More advanced means of control can be obtained by manipulating the paraglider’s risers or lines directly:

Most commonly, the lines connecting to the outermost points of the wing’s leading edge can be used to induce the wingtips to fold under. The technique, known as ‘big ears’, is used to increase rate of descent (see picture).

The risers connecting to the rear of the wing can also be manipulated for steering if the brakes have been severed or are otherwise unavailable.

In a ‘B-line stall’, the second set of risers from the leading-edge/front is gently pulled down to put a crease across the lower surface of the wing (this will also distort the upper surface) acting as an ‘air brake’ significantly reducing airspeed. The combination of reduced forward airspeed and increased vertical airspeed destroys the laminar flow of air over the aerofoil, dramatically reducing the lift produced by the canopy, thus inducing a higher rate of descent.

Fast Descents

Big Ears, Rocky Point, NY.

Problems with etting down can occur when the lift situation is very good or when the weather changes unexpectedly. There are three possibilities of rapidly reducing altitude in such situations, each of which has benefits and issues to be aware of:

Big ears induces descent rates of 2m/s or so. It is the most controllable of the techniques, and the easiest for beginners to learn.

A B-line stall induces descent rates of 5m/s or so. It increases loading on parts of the wing (the pilot’s weight is mostly on the B-lines, instead of spread across all the lines). There is not a risk of the pilot becoming disoriented as a result of using this technique.

A spiral dive offers the fastest rate of descent, at 10-15m/sec. It places greater loads on the wing than other techniques do, and requires the highest level of skill from the pilot to execute safely.

Big Ears

By pulling on the outer A-lines the wing tips of the glider can be folded in. This method drastically deteriorates the glide angle with only a small decrease in forward speed. The effectiveness of this technique can be increased by using the speed system at the same time.

To reinflate on a low performance glider (e.g. DHV1 rated) it is simply necessary to release the lines. On higher performance gliders (e.g. DHV1/2 and above) it may be necessary to help the reinflation with brief, deep pumps of the brakes.

Whilst big ears are in use, the loading on the remaining flying surface of the glider is increased and it is therefore more stable and less prone to collapse. However there is an increased increase of stalling because ‘pulling the ears’ increases the angle of attack and reduces the speed of the wing. So while ‘ears’ and speed bar is a good combination, ‘ears’ and brake is not – it is best not to use the brakes when the ears are ‘in’.

B-Line stall

In a ‘B-line stall’, the second set of risers from the leading-edge/front (the B-lines) are pulled down independently of the other risers. This puts a crease in the upper surface of the wing, thereby destroying the laminar flow of air over the aerofoil. This dramatically reduces the lift produced by the canopy and thus induces a higher rate of descent.

The B-line stall should be initiated with the wing in normal flight (no speed bar; not accelerated). Grasp the B-lines on both sides above the line links and pull them down. There is no need to release the toggles while B-stalling. DHV 1/2 wings are very resistant to creasing; the pilot may have pull on the B-lines with sufficient force to almost lift themself out of the seat to get the wing to crease. Once the crease is in, it requires less effort to keep it in that it does to initiate it.

The sensation for the pilot when the B-line stall is induced is that the breeze is upwards rather than in your face. Pulling the B-lines even further down will not enhance the sink rate, but can lead to a more unstable flight position.

To recover from the B-line stall, release the B-risers so that the aerofoil shape of the wing is resumed. This will normally be sufficient to resume normal flight, but if the canopy remains in a stall push forward gently on the A-risers to lower the leading edge of the wing and reattach the laminar airflow to the upper surface of the wing.

Spiral Dive

The spiral dive is the most rapid form of controlled fast descent. With a little bit of practice you will achieve a sink rate of 15 m/s and more.

However, spiral dives put strong G-forces on the wing and glider and must be done carefully and skilfully. The G-forces involved can induce blackouts, and the rotation can produce disorientation. Spiral dives, as with all paragliding techniques, are best learned under expert supervision. Paragliding ‘SIV’ courses offer a chance to practice spiral dives over water with a rescue boat standing by.

The spiral dive is initiated by pulling the brake on one side and holding it down. Constant pulling on one brake narrows the radius of the turn and forms a spiral rotation in which high sink rates can be reached. As soon as the glider is in a spiral dive (clear increase of sink rate and turn bank), the outside wing should always be stabilised with the outside brake and the desired sink rate should be controlled with great delicacy.

Flying

Take off from a ramp, Tegelberg, Schwangau, Germany.

Launching

Paraglider reverse launch demonstration video

Reverse launch, Fiesch, Switzerland.

Paraglider towed launch, Mirosawice, Poland.

As with all aircraft, launching and landing are done into wind (though in mountain flying, it is possible to launch in nil wind and glide out to the first thermal).

Forward launch

In low winds, the wing is inflated with a orward launch, where the pilot runs forward so that the air pressure generated by the forward movement inflates the wing.

Reverse launch

In higher winds, particularly ridge soaring, a everse launch is used, with the pilot facing the wing to bring it up into a flying position, then turning under the wing to complete the launch.

Reverse launches have a number of advantages over a forward launch. It is more straight forward to inspect the wing and check the lines are free as it leaves the ground. In the presence of wind, the pilot can be tugged toward the wing and facing the wing makes it easier to resist this force, and safer in case the pilot slips (as opposed to being dragged backwards). These launches are normally attempted with a reasonable wind speed making the ground speed required to pressurise the wing much lower – the pilot is initially launching while walking forwards as opposed to running backward.

Towed launch

Paraglider launching in Arax, Brazil.

In flatter countryside pilots can also be launched with a tow. Once at full height, the pilot pulls a release cord and the towline falls away. This requires separate training, as flying on a winch has quite different characteristics from free flying. There are two major ways to tow: Pay-in and pay-out towing. Pay-in towing involves a stationary winch that pays in the towline and thereby pulls the pilot in the air. The distance between winch and pilot at the start is around 500 meters or more. Pay-out towing involves a moving object, like a car or a boat, that pays out line slower than the speed of the object thereby pulling the pilot up in the air. In both cases it is very important to have a gauge indicating daN to avoid pulling the pilot out of the air. There is one other form of towing; tatic towing. This involves a moving object, like a car or a boat, attached to a paraglider or hanglider with a fixed length line. This is very dangerous because now the forces on the line have to be controlled by the moving object itself, which is almost impossible to do. With static line towing a lockout is bound to happen sooner or later. Static line towing is forbidden in most countries and if not, should be avoided at all cost.

Landing

Landing involves lining up for an approach into wind, and just before touching down, laring the wing to minimise horizontal speed. In light winds, some minor running is common. In moderate to medium headwinds, the landings can be without forward speed.

Ridge soaring

In ridge soaring, pilots fly along the length of a ridge feature in the landscape, relying on the lift provided by the air which is forced up as it passes over the ridge.

Ridge soaring is highly dependent on a steady wind within a defined range (the suitable range depends on the performance of the wing and the skill of the pilot). Too little wind, and insufficient lift is available to stay airborne (pilots end up cratching along the slope). With more wind, gliders can fly well above and forward of the ridge, but too much wind, and there is a risk of being lown back over the ridge.

Paraglider in front of Mont Blanc

Thermal flying

When the sun warms the ground, it will warm some features more than others (such as rock-faces or large buildings), and these set off thermals which rise through the air. Sometimes these may be a simple rising column of air; more often, they are blown sideways in the wind, and will break off from the source, with a new thermal forming later.

Once a pilot finds a thermal, he or she begins to fly in a circle, trying to center the circle on the strongest part of the thermal (the “core”), where the air is rising the fastest. Most pilots use a ario (vario-altimeter), which indicates climb rate with beeps and/or a visual display, to help ore-in on a thermal.

Coring: The technique to “core” a thermal is simple: turn tighter as lift decreases, and turn less as lift increases. This ensures you are always flying around the core.

Often there is strong sink surrounding thermals, and there is often also strong turbulence resulting in wing collapses as a pilot tries to enter a strong thermal. Once inside a thermal, shear forces reduce somewhat and the lift tends to become smoother.

Paragliders in the air at Torrey Pines Gliderport

Good thermal flying is a skill which takes time to learn, but a good pilot can often “core” a thermal all the way to cloud base.

Cross-country flying

Once the skills of using thermals to gain altitude have been mastered, pilots can glide from one thermal to the next to go ross-country (C). Having gained altitude in a thermal, a pilot glides down to the next available thermal. Potential thermals can be identified by land features which typically generate thermals, or by cumulus clouds which mark the top of a rising column of warm, humid air as it reaches the dew point and condenses to form a cloud. In many flying areas, cross-country pilots also need an intimate familiarity with air law, flying regulations, aviation maps indicating restricted airspace, etc.

In-flight Wing Deflation (Collapse)

Since the shape of the wing (airfoil) is formed by the moving air entering and inflating the wing, in turbulent air part or all of the wing (airfoil) can deflate (collapse). Piloting techniques referred to as “active flying” will greatly reduce the frequency and severity of deflations or collapses. On modern recreational wings, such deflations will normally recover themselves without pilot intervention. In the event of a severe deflation, correct pilot input will speed recovery from a deflation, but incorrect pilot input may slow the return of the glider to normal flight, so pilot training and practice in correct response to deflations is necessary. For the rare case where it is not possible to recover from a deflation (or from other threatening situations such as a spin), most pilots carry a reserve (rescue, emergency) parachute. Most pilots never have cause to hrow their reserve. In case the wing deflation happens near ground, i.e. shortly after takeoff or just before landing, the wing (paraglider) may not recover (airfoil shape) even with pilot intervention and there may not be enough time for successful rescue parachute deployment. Those cases can result in serious bodily injury or death. In-flight wing deflation and other hazards are minimized by flying a suitable glider and choosing appropriate weather conditions and locations for the pilot’s skill and experience level.

Sports/competitive flying

Some pilots like to stretch themselves beyond recreational flying. For such pilots, there are multiple disciplines available:

Cross-country leagues annual leagues of the greatest distance C flying

“Comps” competitive flying based around completing a number of tasks such as flying around set waypoints

Accuracy spot landing competitions where pilots land on targets with a 3 cm centre spot out to a full 10 meter circle.

“Acro” aero-acrobatic manoeuvres and stunt flying; heart stopping tricks such as helicopters, wing-overs, synchro spirals, infinity tumbles, and so on.

National/international records despite continually improving gliders, these become ever more difficult to achieve; aside from longest distance and highest altitude, examples include distance to declared goal, distance over triangular course, speed over 100 km triangular course, etc.

Competitive flying is done on high performance wings which demand far more skill to fly than their recreational counterparts, but which are far more responsive and offer greater feedback to the pilot, as well as flying faster with better glide ratios.

See also: World Air Games

The current world champion is Andy Aebi of Switzerland; he won the title in February 2009 at Valle de Bravo in Mexico. His predecessor was Bruce Goldsmith.

Safety

This section does not cite any references or sources.

Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (August 2009)

This section contains instructions, advice, or how-to content. The purpose of Wikipedia is to present facts, not to train. Please help improve this article either by rewriting the how-to content or by moving it to Wikiversity or Wikibooks. (October 2009)

Paragliders launching video in Arax.

Paragliding is perhaps often viewed as a higher-risk sport than it actually is. Nonetheless, there is great potential for injury for the reckless or ill-prepared.

The safety of the sport is directly influenced by the skill and sense of the pilot. It’s important to note that almost all paragliding accidents are the result of pilot error. Paragliding equipment is very well built and, if properly cared for, will almost never fail. As an example, the average paraglider has around 30 lines connected to the risers, yet each one is strong enough to support the full weight of a pilot individually. Aerodynamically, newer paragliders that are not within advanced or competition categories are rated for safety and will tend to recover from most incidents on their own (without pilot intervention).

Given that equipment failure of properly certified paragliding equipment can be considered a non-issue, it is accurate to say that paragliding can be a very safe sport. The individual pilot is the ultimate indicator of his or her personal safety level.

In general:

The safe pilot will not fly at sites that pose an unreasonable challenge to his/her flying skills.

The safe pilot will not be influenced by the possibly negative examples set by others.

The safe pilot will only fly on days in which the weather is conducive to safe flight. Turbulence in all its forms is enemy #1 for a flying paraglider wing. Because paragliders have no solid support, their shape (and ability to fly) can be ruined by an errant down draft or the like. Therefore, turbulence or conditions conducive to turbulence generation is a primary factor in determining whether the weather is safe.

The following weather is to be avoided:

Excessive wind speed or gustiness. 15 mph (24 km/h) wind is fairly windy for a paraglider, and most pilots won’t take off in much more wind than that. High winds will also increase the effect of mechanical turbulence. Gusty conditions will make take-offs and landings more dangerous and will make collapses more likely while in flight. The limit of 15 mph is fairly arbitrary, and also depends on local parameters. At some sites people fly safely at 20 mph winds, at other sites 10 mph may be too much.

A wind direction that will not allow a take-off (or landing) into the wind, or at least generally so. Tail-wind take-offs are to be avoided at all cost. Assurance that an [apparent] headwind is not actually a ‘rotor’ is also critical (rotors comprise a form of mechanical turbulence).

Excessively high atmospheric instability, indicated in part by overdeveloped cumulus clouds, or in worse situations by cumulo-nimbus cloud formation. Such conditions will contribute to turbulence. If cumulo-nimbus (thunderstorm) clouds are anywhere in sight, the effect of severe atmospheric instability may exist where you are.

Rain or snow. Because a paraglider wing is made from fabric, it has the ability to absorb moisture. Moreover, the weight (or lack thereof) of a paraglider wing is critical to its performance. Flying into heavy rain or snow will weigh the wing down and may terminate a flight quickly. A wet wing is also less controllable, less stable and will exhibit less tendency to recover into normal flight.

General safety precautions include pre-flight checks, helmets, harnesses with back protection (foam or air-bag), reserve parachutes, and careful pre-launch observation of other pilots in the air to evaluate conditions.

For pilots who want to stretch themselves into more challenging conditions, advanced IV (simulation dncidents en vol, or simulation of flying incidents) courses are available to teach pilots how to cope with hazardous situations which can arise in flight. Through instruction over radio (above a lake), pilots deliberately induce major collapses, stalls, spins, etc, in order to learn procedures for recovering from them. (As mentioned above, modern recreational wings will recover from minor collapses without intervention).

As always, fatalities and freak accidents can occur, but most properly-trained, responsible pilots risk only minor injuries, such as twisted ankles.

Learning to fly

Most popular paragliding regions have a number of schools, generally registered with and/or organized by national associations. Certification systems vary widely between countries, though around 10 days instruction to basic certification is standard.

Flying above Stubaital, Austria

There are several key components to a paragliding pilot certification instruction program. Initial training for beginning pilots usually begins with some amount of ground school to discuss the basics, including elementary theories of flight as well as basic structure and operation of the paraglider.

Students then learn how to control the glider on the ground, practicing take-offs and controlling the wing ‘overhead’. Low, gentle hills are next where students get their first short flights, flying at very low altitudes, to get used to the handling of the wing over varied terrain. Special winches can be used to tow the glider to low altitude in areas that have no hills readily available.

As their skills progress, students move on to steeper/higher hills (or higher winch tows), making longer flights, and learning to turn the glider, control the glider’s speed, then moving on to 360 turns, spot landings, ig ears (used to increase the rate of descent for the paraglider), and other more advanced techniques. Training instructions are often provided to the student via radio, particularly during the first flights.

A third key component to a complete paragliding instructional program provides substantial background in the key areas of meteorology, aviation law, and general flight area etiquette.

Tandem paraglider launch

To give prospective pilots a chance to determine if they would like to proceed with a full pilot training program, most schools offer tandem flights, in which an experienced instructor pilots the paraglider with the prospective pilot as a passenger. Schools often offer pilot’s families and friends the opportunity to fly tandem, and sometimes sell tandem pleasure flights at holiday resorts.

Most recognised courses lead to a national licence and an internationally recognised International Pilot Proficiency Information/Identification card. The IPPI specifies five stages of paragliding proficiency, from the entry level ParaPro 1 to the most advance stage 5.

World records

FAI (Fdration Aronautique Internationale) world records:

Straight distance 461.6 km: Frank Brown, Marcelo Prieto, Rafael Monteiro Saladini (Brazil); Quixada Duque, Brazil; 14 November 2007.

Straight distance to declared goal 368.9 km: Alja Vali, Urban Vali (Slovenia); Vosburg Jamestown (South Africa); 7 December 2006

Gain of height 4526 m: Robbie Whittall (UK); Brandvlei (South Africa); 6 January 1993

Other records (distance/speed for out-and-return and triangular course) can be seen on the FAI site

Recently a flight of over 500 km was made by Nevil Hulett in excellent conditions in South Africa; Flight record

Pilot numbers

A multi-national contingent in the air in Bali

Numbers of actively flying pilots can only be a rough estimate, but France is believed to have the largest number, at around 25,000. Next most active flying countries are Germany, Austria, Switzerland, Japan, and Korea, at around 10,000 20,000, followed by Italy, the UK, and Spain with around 5,000 10,000. The USA has around 4,500. (All as of 2004).

See also

Foot-launched Powered Hang Glider

Glider (sailplane)

Comparison between paragliders, hang gliders and sailplanes

Gliding

Hang gliding

Powered paragliding

Torrey Pines Gliderport

Parahawking

v  d  e

Extreme Sports

Board sports

Snowboarding  Sandboarding  Windsurf  Kitesurfing  Riverboarding  River surfing  Surfing  Flowboarding  Skysurfing  Skateboarding  Mountainboarding  Snowskate   Wakeboarding

Motor sports

Motocross  Snocross  Rallying  Drifting  Motorcycle rally

Water sports

Rafting   Whitewater kayaking  Whitewater canoeing   Free diving   Scuba_diving

Mountaineering

Ice climbing  Rock Climbing  Bouldering  Canyoning  Free solo climbing

Free-fall

Parachuting  Bungee jumping  Wingsuit flying  BASE jumping

Flying

Paragliding  Hang gliding

Others

Mountain biking  BMX  Inline skating   Cliff diving   Paintball   Jibbing

References

^ US Pat. 2734706 – Filed October 17, 1952.

^ Walter Neumark, “The Future of Soaring”, Flight magazine, 14 May 1954

^ History of Paragliding

^ Pilot Profile: David Barish, the Probable Inventor of the Paraglider

^ a b David Barish, The Forgotten Father of Paragliding

^ Jean-Claude Btemps: i invent le parapente

^ FAI Hang Gliding and Paragliding World Records

^ How many pilots worldwide?

External links

Wikimedia Commons has media related to: Paragliding

Paragliding at the Open Directory Project

Categories: Adventure travel | Aircraft configurations | Air sports | Individual sports | ParaglidingHidden categories: All articles with specifically-marked weasel-worded phrases | Articles with specifically-marked weasel-worded phrases from October 2009 | All articles with unsourced statements | Articles with unsourced statements from April 2009 | Articles needing additional references from August 2009 | All articles needing additional references | Articles needing cleanup from October 2009 | All pages needing cleanup | Articles containing how-to sections | Articles lacking in-text citations from February 2008 | All articles lacking in-text citations

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June 6 2011 Solar flare.avi

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very impressive – lets see just how low those planes can fly ?
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AS the year ends, the sun’s activity gears up, flares, spots, and ufo’s around the sun. dec. 27-28

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AURORA WATCH: A series of coronal mass ejections (CMEs) en route to Earth from sunspot 1158 will buffet our planet’s magnetic field during the next 24-48 hours. NOAA forecasters estimate a 45% chance of geomagnetic activity on Feb. 17th. High-latitude sky watchers should be alert for auroras. AMAZING SUNSPOT MOVIE: Less than a week ago, sunspot 1158 didn’t exist. Now it is wider than the planet Jupiter and unleashing the strongest solar flares since Dec. 2006. Witness the amazing 5-day development of this active region, courtesy of NASA’s Solar Dynamics Observatory:

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SOLAR FLARE EARTH DIRECTED M6 6 SUN SPOT 1158 THIS IS THE STRONGEST CME THIS YEAR FEB 13 2011 2012
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CORPORATE ASTROLOGY AND EFFECTS OF VARIOUS PLANETS

 

Corporate Astrology is the concept being developed by me though the signification of certain commodities, rather, every thing is attributed to the Planets by our sages. However, the principles laid down by our sages need to be interpreted with reference to modern times. Corporate astrology is the application of astrological principles to the companies, firms, institutions, organizations etc. It is pertinent to mention that it is on account of planetary forces that certain companies fail miserably and others prosper well. For the study of the company’s horoscope, apart from the date the birth-details of the Managing Director and one key person i.e. the whole – time or executive director and one key person i.e. the whole – time or executive director etc. the combined study would enables as to guide the prospects of the company and steps it would take to ensure prosperity.

 

It may not be possible to dwell at length with reference to all the astrological principle to but and attempt shall be made to tell about the commodities ruled by planets – the companies ruled by the plantes with brief reference to Naskshatra responsible for a particular commodity or product etc.

 

Connected with corporate astrology, a mention to the recent Solar Eclipse on 24th October, 1995 is inevitable; it has the effect of increasing the cost of ghee, edible oils, oil seeds, wheet (food grains), apples, carrot, tomatoes etc. Refer to my interview on Doordarshan on 19.10.1995 at 12.40PM – Metro channel and news in item in Sunday Observor dated 22.10.1995.

 

It is known to all that the Sun is the Central gigue and predominates over the entire celestial system. It owns the sings Leo and reles over Nakashatra Kritika, Uttara-phalguni and Uttar-ashada. The Sun represent Gold, Ruby, Pearls (Pearls also gets under the Moon), government’s financial schemes, banking business and financial institutions, with association of Mars, all electrical and electronic goods and their manufacture. Since the Sun is EYE apart from the Moon, all optical spectacles glasses business, jeweler and copper ornaments, metals, steel though mainly under Saturn is also attributed to the sun, though mainly attributed to Saturn and mars, Grass, dealings with affairs personal or social (public relations department of the companies would also come under the Sun) Blood red cloth, shores of a river, Red sandal paste or saffron, thick or coarse yard etc.

 

Leo Born persons ruled by the Sun i.e. those during 23rd July to 23rd August or those whose birth number is 1, 10 and 19 are aristocracies and live with royalty are aristocracies and live with royalty. Normally fortunate and earn from speculation. They earn as investors and nor as brokers. Benefits are drawn a from the transactions in above commodities or the companies dealing with those commodities.

 

Cotton market is expected to flare up when the Sun and the Mars come into one Nakshtra. This is a principle to be watched and applied.

 

With reference to modern times, the companies under the domain of the Sun are Ashok Leyland, Premier Padmni, Marut Udhyog, Tata Iron and Steel, Mukund Steel etc. with reference to Sun’s Nakshtras, Kritka speak of garlics, sun-flowers, green/red grams and also black (though some attribute to Saturn) and Urand. Uttara-Shada refers to lamfs, bulbs, furnaces, petro chemicals, words blades and also electronics.

 

THE MOON:

Peace loving and security minded planet the Moon owns the Sign Cancer and governs the Nakshatras Rohini, Hasta and Saravna. With regard to commodities and companies, all matters relating to shopping, exports, alcohols, aerated waters, cold drinks (rather all liquids). Salts, silver jewelery, aluminum products, Boat clubs, swimming pool, snow, powdered products, mild perfumes, marine products, conchs, coconuts, stout sugarcane, water tanks whiteness and white things, fishing and fish industry, honey, Umbrella (Rahu also governs Umbrellas) Refind clothes. In addition, Roohini Nakshatra refers to Banana, lemons and sour fruits and food grains Hasta signifies perfumes, camphor, scants, sandal, hand gloves of rubbers and Sravana speak of curds, buttermilk, milk, holy-water say of the sacred River Ganges, betal nuts, chemicals, medicines, cast iron and lead etc.

 

Cancerian born person are ruled by the Moon i.e. those born between 22nd June to 23rd July and also those born on 2, 11 or 20 will gains from the above commodities or companies dealing with them. These people are very cautiously enterprising people and most of them benefit from long tem investments only. Some of them earn on account of their God-gifted institution and also impulsive trading. Such persons haven been found to be highly connected persons-VIPs. In some of the cases it has been that they earn better while doing business in the name of other persons. In addition, such person must stand informed about the latest market condition Fortunes come to them from exports or overseas connections.

 

Ups and downs in the market and daily fluctuations in the share market are mainly governed by the Moon and Mercury supported by the bandit of malefic influences of Jupiter who is signification of plenty and prosperity but at the same time responsible for slump or depreciation.

 

MARS:

Mars the Universal Lord is also pervasive in various matters concerning the corporate sector. Mars owns Aries and Scorpio and rules over Nakshatra Mrigsara, Chita and Dhanishtha. Steal, motors rails etc. get to Mars. Elaborating the filed of Mars in the corporate sector, it is stated that it signifies, iron, steel, electricity (all products connected with electronics), furnaces, Burning, gas, tobacco, cigarettes, petro-chemicals, metals, copper cement (thought also under Saturn), stones/tiles Marbles, Dynamites, Explosive, Bombs and Missiles, Radiators, Welding machines and connected works, carpentry (wooden work). Detergents, Plastic Processing. The Nakshatras of Mars add and say : Mrigsara signify quadrupeds, Teeth Hormy animals. Stag Skins, Arms for hunting, Arrows and Bows, Guns and spears. Chritra refers to precious and semi-precious metals including old ornaments, luxury articles and auto-accessories, vehicles, shopsCinemas, Textiles Industries. Dhanishta refers to Iron, Gold, Wheat, Industry, Mills, Factories, Safe Vaults etc.

 

Aries born i.e. between 21st March to 20th April, and Scorpio born between 24th October to 22nd November stand to gain form the above commodities inducing the companies dealing with above commodities. Similarity person born 3,9,12,18,27 are benefited from the above companiesfirms. However it is found that Ariens are hasty whereas the scorpions are steady it is found that Ariens are hasty whereas the scorpions are steady. At the same time Ariens are hasty whereas the scorpions are more mature and have patience for long tem investments and consequently gain more.

 

Shares of the following companies come under Mars: Bharat Petrolium, Indian Aluminium, Atul Products, Cochin Refinery, Gujrat Fertilizers, India Cement, Alembic Chemicals.

 

MERCURY:

The planet of Wings and Lord of trading activity, Mercury owns Gemini and Virgo and rules Nakshatra Ashlesh, Jashthay and Revil. Broadly, the Mercury rules over Silver, Pearls (Pearl also come under the Sun and The Moon), Emaralds, vegetables.

 

Horses (though fall underAswini) and also horse-trading (race courses), Construction of Places, Vedanta system of philosophy, Doctor/Medical practitioner, Theatres for dances and laughing (jokers), Mixtures of various substance (compounds), Birds and trading in birds, gardens/nurseries,

 

Nakshtras of Mercurry indicate more things relevant for the corporate sector. Aslesha indicate pure silver, mercury (quick silver, sugar candy, green greases, juicy vegetables, water-animals) water as snakes; crab etc, though they also come under Scorpio. Jeyshth refer to inflammable oile, chemical, googol, and Revti takes into accounts coconuts, betel, dispensary, films and film actors, books, library, schools etc.

 

Persons between 22nd May to 21st June (Gemini) and born between 24th August to 23rs September (Virgo) gain from above fields. Persons with date of birth ad 5, 14, 23 also get benefited. Actually this is a class of purely intellectuals like business magnetism shattered accountants, brokers, financers, money lenders etc. Most of these persons benefit from share market. Gemini’s though double minded are great entrepreneurs but Virgoans are wisest investors and business counselors including Masters of Business Administration. Apart from the above fields, these corporate men gain from financing, leasing, insurance, computer machines, pharmaceuticals and toy industry, transport and communication, brokerage, clubs/casinos, gambling’s, publication, printery, etx.

 

Mercury rules leasing and financing companies, banks mutual schemes, Zenith Computers, Vem Organic, Sandoz Pharma, Tata Chemicals and similar companies.

 

JUPITER:

Jupiter owns Saggitarius and Pisces in the Zodiac, Nakshatras ruled by Jupiter are Purnavasu, Visakha and Poorvabhadrapad. In general Jupiter rules ever share-market, Zine, tin, topaz, steel, chocolates, paper, stationary, printing, bookshop, newspapers, banking financing, trusts and other charitable institutions, hospitals, aluminum, gold, capital estate, educational institutions, i.e. schools and colleges, public service, of the Managing Director/Chairman of the company) soft and pleasant stones, according to Nakshatras of Jupiter, Punavasu also signify fold and silver, jowar, cloth, book, pens, stationery, TVs, dancers etc and skin of trees, medicines, sweets, ghee, coins, wines, inns, hotels etc.

 

Persons born between 23rd November to 31st December (Saggitarians) and Persons born between 20th February to 20th March (Pisceans) and Person born on 3, 12 and 21st can prosper from the long term investments and long-term financial schemes., Pisceans should be careful because rich dividends may not come on account of Saturn but Saggitarians can reap good income as even Rahu can bring unexpected results.

 

Jupiterians can gain from shares of paper and pulp industry trees processing, Tata Tea, Raymond Woolen, companies dealing in edible oils i.e. Amrit Vanaspati etc. companies engaged in food processing i.e. Godrej Foods etc.

 

I say something more about Jupiter. If Jupiter aspects the Sun immediately on its entry into another sing, the slump in the markets of cotton and oil seeds cannot be rules out. There is over recession whenever the Saturn is in opposition of Jupiter. Thursday ruled by Jupiter has also a say in the matter – there will be a fall in general in share and commodity markets when there are five Thursdays in the Indian month.

 

VENUS

 

Venus is the planet of luxurious goods including highly sophisticated good. Venus  owns Taurus and Libra and rules over Bhani Poorva-Falguni and Poorva-ashada. In general Venus, form corporate astrological point of view, stand for copper, silk, cosmetics, high-class cloth inducing silk, soaps/ cosmetics/ beauty parlors, all types of decorations, foods and hotels, conned goods, real and imitation Jewelery, film, industry, pornography and music, all fancy items, fashion shows diamond. White colors also go to the Venus apart from pleasant musical instruments. The Nakshtras of Venus add to the above items, Bharni is for Chilies, medicine, hair oil etc. Poorva Falguni signifies wood, shining silk, jowar, sliver and gold, royal dress etc. Poorva-ashad signify Sandal, gold, diamond, rose water, perfumes, ice ghee etc.

 

Taureans (born between 21st April to 21st May) and Liberans (born between 24th September to 23rd October) and those born on 6, 15 and 24 would gain and an commercially minded. Taureans are security-minded but are luck to get easy money sometimes with out much efforts. Liberans have to work hard.

 

Following companies and their shares prove gainful to Liberans and Taureans:

 

Company’s engaed in fine tetiles-Bombay Rayon, Bhilwara Suitings, Gwalior Rayon, Videocon etc.

 

Cosmo-Films, hotel companies, Colgate Palmoliga etc.

 

SATURN:

The planet of destiny had also a major role to play in the development of corporate infra-structures. Saturn owns two signs Capricorn and Aquirius and rules Pusphya, Anuradha and Uttra-bhadraped. From commercial point of view i.e. corporate sector, Saturn in general stand for coal mines, lead, chemicals, steel plants, iron compressor’s, pumps, all types of  machines, timber woods, bricks and cement, land and agricultural lands, hardware items, automobiles accessories (also in the domain of the Sun), titles/marbles, Nakshatra of Saturn add to these items: Pusphya Stand for ghee and gold, turmeric, rice, salt, butter, banana, rice, grams, jowar, coconut, ground nuts, chemicals specially connected with earth etc. Uttara-bhadra speak of drugs, strong wines, vicious drinks, tobacco stones, boots, leather, sugar canes etc.

 

Capricoms (born between 22nd December to 20th January) and Aqurians (born 21st January to 19th February) and also those born on 8, 17 or 26 of any month gains from above fields Capricornians are basically hard-working and need security of life. On the other hand Aqurians are fast, speculative and moderately enterprising. Rash speculation ends in enormous losses at times. Trading in shares is not advised not to do any risky trading/deals in the market specially for those who are born on 8, 17 or 26. MUST NOT BE SPECULATING IN ANY MARKET. Only long term investments are helpful. Patience is the key to success for them and they get amply awarded from slow moving projects.

 

The beneficial companies for these people are Steel Companies Say Tata, Mukund etc. Bajaj Electricals, Escorts Tractors etc in addition, we may name Kinetic Honda, Metal Box, Rathi Ispat etc.

 

Solar ingress on Saturday results in good rise in the markets of cotton and oil seeds, Similarly, Saturn with Mars aspecting the Sun may flare up the said market.

 

For want of time, I am not referring to Rahu and Ketu. But the effects have to be reduced from their placement, association, connection and aspect etc. keeping in mind the proverb ‘Shani Vat Rahu Kuja Vat Ketu’ i.e. Rahu is Saturn and Ketu is Mars.

Dr. Shanker Adawal, Jyotishacharya in Astrology is a professional and Astrology is his passion and an urge. His predictive technique is based on Bhrigu Technique whose principles and doctrines have been deciphered from research of above two decades . He is a professional in the field of telecommunications. He is presently working for one of the Fortune 500 Indian companies at a senior position. Did his MBA and PhD. and worked with Multinationals in India and abroad, before joining his presnt assignment. He has travelled extensively both in India and abroad. He also has keen interest in Human Rights.He got interested in astrology when he was young, did his Jyotishacharya. His desire and aspiration to share the findings of his research and the new dimensions which can be given to the science of astrology. www.connectingmind.com


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Radio Propagation

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Free space propagation

In free space, all electromagnetic waves (radio, light, X-rays, etc) obey the inverse-square law which states that the power density of an electromagnetic wave is proportional to the inverse of the square of the distance from the source or:

Doubling the distance from a transmitter means that the power density of the radiated wave at that new location is reduced to one-quarter of its previous value.

The power density per surface unit is proportional to the product of the electric and magnetic field strengths. Thus, doubling the propagation path distance from the transmitter reduces each of their received field strengths over a free-space path by one-half.

Modes

Radio frequencies and their primary mode of propagation

Band

Frequency

Wavelength

Propagation via

VLF

Very Low Frequency

330 kHz

10010 km

Guided between the earth and the ionosphere.

LF

Low Frequency

30300 kHz

101 km

Guided between the earth and the D layer of the ionosphere.

Surface waves.

MF

Medium Frequency

3003000 kHz

1000100 m

Surface waves.

E, F layer ionospheric refraction at night, when D layer absorption weakens.

HF

High Frequency (Short Wave)

330 MHz

10010 m

E layer ionospheric refraction.

F1, F2 layer ionospheric refraction.

VHF

Very High Frequency

30300 MHz

101 m

Infrequent E ionospheric refraction. Extremely rare F1,F2 layer ionospheric refraction during high sunspot activity up to 80 MHz. Generally direct wave. Sometimes tropospheric ducting.

UHF

Ultra High Frequency

3003000 MHz

10010 cm

Direct wave. Sometimes tropospheric ducting.

SHF

Super High Frequency

330 GHz

101 cm

Direct wave.

EHF

Extremely High Frequency

30300 GHz

101 mm

Direct wave limited by absorption.

Surface modes

Main article: Surface wave

Lower frequencies (between 30 and 3,000 kHz) have the property of following the curvature of the earth via groundwave propagation in the majority of occurrences.

In this mode the radio wave propagates by interacting with the semi-conductive surface of the earth. The wave “clings” to the surface and thus follows the curvature of the earth. Vertical polarization is used to alleviate short circuiting the electric field through the conductivity of the ground. Since the ground is not a perfect electrical conductor, ground waves are attenuated rapidly as they follow the earth surface. Attenuation is proportional to the frequency making this mode mainly useful for LF and VLF frequencies.

Today LF and VLF are mostly used for time signals, and for military communications, especially with ships and submarines. Early commercial and professional radio services relied exclusively on long wave, low frequencies and ground-wave propagation. To prevent interference with these services, amateur and experimental transmitters were restricted to the higher (HF) frequencies, felt to be useless since their ground-wave range was limited. Upon discovery of the other propagation modes possible at medium wave and short wave frequencies, the advantages of HF for commercial and military purposes became apparent. Amateur experimentation was then confined only to authorized frequency segments in the range.

Direct modes (line-of-sight)

Line-of-sight is the direct propagation of radio waves between antennas that are visible to each other. This is probably the most common of the radio propagation modes at VHF and higher frequencies. Because radio signals can travel through many non-metallic objects, radio can be picked up through walls. This is still line-of-sight propagation. Examples would include propagation between a satellite and a ground antenna or reception of television signals from a local TV transmitter.

Ground plane reflection effects are an important factor in VHF line of sight propagation. The interference between the direct beam line-of-sight and the ground reflected beam often leads to an effective inverse-fourth-power law for ground-plane limited radiation. [Need reference to inverse-fourth-power law + ground plane. Drawings may clarify]

Ionospheric modes (skywave)

Main article: Skywave

Skywave propagation, also referred to as skip, is any of the modes that rely on refraction of radio waves in the ionosphere, which is made up of one or more ionized layers in the upper atmosphere. F2-layer is the most important ionospheric layer for HF propagation, though F1, E, and D-layers also play some role. These layers are directly affected by the sun on a daily cycle, the seasons and the 11-year sunspot cycle determines the utility of these modes. During solar maxima, the whole HF range up to 30 MHz can be used and F2 propagation up to 50 MHz are observed frequently depending upon daily solar flux values. During solar minima, propagation of higher frequencies is generally worse.

Forecasting of skywave modes is of considerable interest to amateur radio operators and commercial marine and aircraft communications, and also to shortwave broadcasters.

Meteor scattering

Meteor scattering relies on reflecting radio waves off the intensely ionized columns of air generated by meteors. While this mode is very short duration, often only from a fraction of second to couple of seconds per event, digital Meteor burst communications allows remote stations to communicate to a station that may be hundreds of miles up to over 1,000 miles (1,600 km) away, without the expense required for a satellite link. This mode is most generally useful on VHF frequencies between 30 and 250 MHz.

Auroral reflection

Intense columns of Auroral ionization at 100 km altitudes within the auroral oval reflect radio waves, perhaps most notably on HF and VHF. The reflection is angle-sensitive – incident ray vs. magnetic field line of the column must be very close to right-angle. Random motions of electrons spiraling around the field lines create a Doppler-spread that broadens the spectra of the emission to more or less noise-likeepending on how high radio frequency is used. The radio-auroras are observed mostly at high latitudes and rarely extend down to middle latitudes. The occurrence of radio-auroras depends on solar activity (flares, coronal holes, CMEs) and annually the events are more numerous during solar cycle maximas. Radio aurora includes the so-called afternoon radio aurora which produces stronger but more distorted signals and after the Harang-minima, the late-night radio aurora (sub-storming phase) returns with variable signal strength and lesser doppler spread. The propagation range for this predominantly back-scatter mode extends up to about 2000 km in east-west plane, but strongest signals are observed most frequently from north at nearby sites on same latitudes.

Rarely, a strong radio-aurora is followed by Auroral-E, which resembles both propagation types in some ways.

Sporadic-E propagation

Sporadic E (Es) propagation can be observed on HF and VHF bands. It must not be confused with ordinary HF E-layer propagation. Sporadic-E at mid-latitudes occurs mostly during summer season, from May to August in the northern hemisphere and from November to February in the southern hemisphere. There is no single cause for this mysterious propagation mode. The reflection takes place in a thin sheet of ionisation around 90 km height. The ionisation patches drift westwards at speeds of few hundred km per hour. There is a weak periodicity noted during the season and typically Es is observed on 1 to 3 successive days and remains absent for a few days to reoccur again. Es do not occur during small hours; the events usually begin at dawn, and there is a peak in the afternoon and a second peak in the evening. Es propagation is usually gone by local midnight.

Maximum observed frequency (MOF) for Es is found to be lurking around 30 MHz on most days during the summer season, but sometimes MOF may shoot up to 100 MHz or even more in ten minutes to decline slowly during the next few hours. The peak-phase includes oscillation of MOF with periodicity of approximately 5…10 minutes. The propagation range for Es single-hop is typically 1000 to 2000 km, but with multi-hop, double range is observed. The signals are very strong but also with slow deep fading.

Thomas F. Giella, retired meteorologist, space plasma physicist and an Amateur Radio Operator (NZ4O), cites the following from his professional research:[citation needed][original research?]

Just as the E layer is the main refraction medium for medium frequency (3003000 kHz) signal propagation within approximately 5000 km (3000 mi), so is a Sporadic-E (Es) cloud. Sporadic-E (Es) clouds occur at approximately 100 km (60 mi) in altitude and generally move from ESE to WNW. Like Stratosphere level warming and Troposphere level temperature and moisture discontinuities, Sporadic-E (Es) clouds can depending on the circumstances absorb, block or refract medium, high and very high frequency RF signals in an unpredictable manner.

The main source for “high latitude” Sporadic E (Es) clouds is geomagnetic storming induced radio aurora activity.

The main source for “mid latitude” Sporadic-E (Es) clouds is wind shear produced by internal buoyancy/gravity waves (IBGW’s), that create traveling ionosphere disturbances (TID’s), most of which are produced by severe thunderstorm cell complexes with overshooting tops that penetrate into the Stratosphere. Another tie in between Sporadic-E (Es) and a severe thunderstorm is the Elve.

The main sources for “low latitude” Sporadic-E (Es) clouds is wind shear produced by internal buoyancy/gravity waves (IBGW’s), that create traveling ionosphere disturbances, most of which are produced by severe thunderstorm cell complexes tied to tropical cyclones. High electron content in the Equatorial Ring Current also plays a role.

The forecasting of Sporadic-E (Es) clouds has long been considered to be impossible. However it is possible to identify certain troposphere level meteorological conditions that can lead to the formation of Sporadic E (Es) clouds. One is as mentioned above the severe thunderstorm cell complex.

Sporadic-E (Es) clouds have been observed to initially occur within approximately 150 km (90 mi) to the right of a severe thunderstorm cell complex in the northern hemisphere, with the opposite being observed in the southern hemisphere. To complicate matters is the fact that Sporadic-E (Es) clouds that initially form to the right of a severe thunderstorm complex in the northern hemisphere, then move from ESE-WNW and end up to the left of the severe thunderstorm complex in the northern hemisphere. So one has to look for Sporadic-E (Es) clouds on either side of a severe thunderstorm cell complex. Things get even more complicated when two severe thunderstorm cell complexes exist approximately 10002000 miles apart.

Not all thunderstorm cell complexes reach severe levels and not all severe thunderstorm cell complexes produce Sporadic-E (Es). This is where knowledge in tropospheric physics and weather analyses/forecasting is necessary.

Some of the key elements in identifying which severe thunderstorm cell complexes have the potential to produce Sporadic-E (Es) via wind shear, from internal buoyancy/gravity waves, that produce traveling ionosphere disturbances include:

1.) Negative tilted mid and upper level long wave troughs.

2.) Approximate 150 knot (170 mph, 280 km/h) jet stream jet maxes that produce divergence and therefore create a sucking vacuum effect above thunderstorm cells, that assist thunderstorm cells in reaching and penetrating the tropopause into the stratosphere.

3.) 500 mb (50 kPa) temperatures of 20 C or colder, which produce numerous positive and negative lightning bolts and inter-related Sprites and Elves.

4.) Approximate 150175 knot (170200 mph) updrafts within thunderstorm cells complexes that create overshooting tops that penetrate the Tropopause into the Stratosphere (See definition #20 on Stratospheric Warming), launching upwardly propagating internal buoyancy/gravity waves, which create traveling ionosphere disturbances and then wind shear.

Tropospheric modes

Tropospheric scattering

At VHF and higher frequencies, small variation (turbulence) in the density of the atmosphere at a height of around 6 miles (10 km) can scatter some of the normally line-of-sight beam of radio frequency energy back toward the ground, allowing over-the-horizon communication between stations as far as 500 miles (800 km) apart. The military developed the White Alice communications system covering all of Alaska, using this tropospheric scattering principle.

Tropospheric ducting

Sudden changes in the atmosphere’s vertical moisture content and temperature profiles can on random occasions make microwave and UHF & VHF signals propagate hundreds of kilometers up to about 2,000 kilometers (1,300 mi)nd for ducting mode even farthereyond the normal radio-horizon. The inversion layer is mostly observed over high pressure regions, but there are several tropospheric weather conditions which create these randomly occurring propagation modes. Inversion layer’s altitude for non-ducting is typically found between 100 meters (300 ft) to about 1 kilometer (3,000 ft) and for ducting about 500 meters to 3 kilometers (1,600 to 10,000 ft), and the duration of the events are typically from several hours up to several days. Higher frequencies experience the most dramatic increase of signal strengths, while on low-VHF and HF the effect is negligible. Propagation path attenuation may be below free-space loss. Some of the lesser inversion types related to warm ground and cooler air moisture content occur regularly at certain times of the year and time of day. A typical example could be the late summer, early morning tropospheric enhancements that bring in signals from distances up to few hundred kilometers for a couple of hours, until undone by the Sun’s warming effect.

Tropospheric delay

This is a source of error in radio ranging techniques, such as in GPS.

Rain scattering

Rain scattering is purely a microwave propagation mode and is best observed around 10 GHz, but extends down to a few gigahertzhe limit being the size of the scattering particle size vs. wavelength. This mode scatters signals mostly forwards and backwards when using horizontal polarization and side-scattering with vertical polarization. Forward-scattering typically yields propagation ranges of 800 km. Scattering from snowflakes and ice pellets also occurs, but scattering from ice without watery surface is less effective. The most common application for this phenomenon is microwave rain radar, but rain scatter propagation can be a nuisance causing unwanted signals to intermittently propagate where they are not anticipated or desired. Similar reflections may also occur from insects though at lower altitudes and shorter range. Rain also causes attenuation of point-to-point and satellite microwave links. Attenuation values up to 30 dB have been observed on 30 GHz during heavy tropical rain.

Aeroplane scattering

Aeroplane scattering (or most often reflection) is observed on VHF through microwaves and besides back-scattering, yields momentary propagation up to 500 km even in a mountain-type terrain. The most common back-scatter application is air-traffic radar and bistatic forward-scatter guided-missile and aeroplane detecting trip-wire radar and the US space radar.

Lightning scattering

Lightning scattering has sometimes been observed on VHF and UHF over distance of about 500 km. The hot lightning channel scatters radiowaves for a fraction of a second. The RF noise burst from the lightning makes the initial part of the open channel unusable and the ionisation disappears soon because of combination at low altitude high atmospheric pressure. Although the hot lightning channel is briefly observable with microwave radar, this mode has no practical use for communications.

Other effects

Diffraction

Knife-Edge diffraction is the propagation mode where radio waves are bent around sharp edges. For example, this mode is used to send radio signals over a mountain range when a line-of-sight path is not available. However, the angle cannot be too sharp or the signal will not diffract. The diffraction mode requires increased signal strength, so higher power or better antennas will be needed than for an equivalent line-of-sight path.

Diffraction depends on the relationship between the wavelength and the size of the obstacle. In other words, the size of the obstacle in wavelengths. Lower frequencies diffract around large smooth obstacles such as hills more easily. For example, in many cases where VHF (or higher frequency) communication is not possible due to shadowing by a hill, one finds that it is still possible to communicate using the upper part of the HF band where the surface wave is of little use.

Diffraction phenomena by small obstacles are also important at high frequencies. Signals for urban cellular telephony tend to be dominated by ground-plane effects as they travel over the rooftops of the urban environment. They then diffract over roof edges into the street, where multipath propagation, absorption and diffraction phenomena dominate.

Absorption

Low-frequency radio waves travel easily through brick and stone and VLF even penetrates sea-water. As the frequency rises, absorption effects become more important. At microwave or higher frequencies, absorption by molecular resonance in the atmosphere (mostly water, H2O and oxygen, O2) is a major factor in radio propagation. For example, in the 5860 GHz band, there is a major absorption peak which makes this band useless for long-distance use. This phenomenon was first discovered during radar research during World War II. Beyond around 400 GHz, the Earth’s atmosphere blocks some segments of spectra while still passes somehis is true up to UV light, which is blocked by ozone, but visible light and some of the NIR is transmitted.

Heavy rain and snow also affect microwave reception.

See also

Radio portal

Main article: List of radio propagation terms

Diversity scheme

Earth bulge

Electromagnetic radiation

Fading

Fresnel zone

Free space

Inversion (meteorology)

Kennellyeaviside layer

Near and far field

Radio frequency

Radio horizon

Radio propagation model

Rayleigh fading

Ray tracing (physics)

Schumann resonance

Skip (radio)

Skip zone

Skywave

Tropospheric propagation

TV and FM DX

References

^ H. P. Westman et al., (ed), Reference Data for Radio Engineers, Fifth Edition, 1968, Howard W. Sams and Co., no ISBN, Library of Congress Card No. 43-14665 page 26-1

^ Demetrius T Paris and F. Kenneth Hurd, Basic Electromagnetic Theory, McGraw Hill, New York 1969 ISBN -0 048470-8, Chapter 8

^ Westman Reference data page 26-19

Larry D. Wolfgang et al., (ed), The ARRL Handbook for Radio Amateurs, Sixty-Eighth Edition , (1991), ARRL, Newington CT USA ISBN 0-87259-168-9

Further reading

Lucien Boithais: Radio Wave Propagation. McGraw-Hill Book Company, New York. 1987. ISBN 0-07-006433-4

Karl Rawer:Wave Propagatiom im the Ionosphere.Kluwer Acad.Publ.,Dordrecht 1993. ISBN 0-7923-0775-5

External links

Wikimedia Commons has media related to: Radio propagation

Online Propagation Tools, HF Solar Data, and HF Propagation Tutorials

DXing.info – Propagation links

Solar Cycle 24 and VHF Aurora Website (www.solarcycle24.com)

Ionospheric Prediction Service – Australia

Unusual HF Propagation Phenomena. 13 Apr 2009 Includes useful recordings each type. Retrieved 9 Oct 2009.

HF Radio Propagation Software for Firefox – Propfire Firefox plug for monitoring radio propagation, website utility to display HF radio propagation status and article on understanding HF radio propagation forecasting

RadioWORKS A radio wave propagation and antenna length calculator

SWDXER The SWDXER – with general SWL information and radio antenna tips.

Space Weather and Radio Propagation Resource Center Live data and images of space weather and radio propagation.

ARRL Propagation Page The American Radio Relay League page on radio propagation.

The Basics of Radio Wave Propagation A resource by Edwin C. Jones (AE4TM), MD, PhD, Department of Physics and Astronomy, University of Tennessee.

“NZ4O 160 Meter Propagation Theory Notes”. A website dedicated to layman level explanations of “seemingly” mysterious 160 meter (MF/HF) propagation occurrences. http://www.wcflunatall.com/nz4o5.htm. 

Dynamic Radio Propagation Data Constantly updated radio propagation data pulled from various sources.

The following external references provide practical examples of radio propagation concepts as demonstrated using software built on the VOACAP model.

High Frequency radio propagation de-mystified.

Is High Frequency radio propagation reciprocal?

How does noise affect radio signals?

The following external link is designed for use by cell phones and mobile devices that can display content using Wireless Markup Language and the Wireless Application Protocol:

WAP/WML Space Weather and Radio Propagation Resources Space weather and radio propagation resources.

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Radio spectrum

ELF

3 Hz

30 Hz

SLF

30 Hz

300 Hz

ULF

300 Hz

3 kHz

VLF

3 kHz

30 kHz

LF

30 kHz

300 kHz

MF

300 kHz

3 MHz

HF

3 MHz

30 MHz

VHF

30 MHz

300 MHz

UHF

300 MHz

3 GHz

SHF

3 GHz

30 GHz

EHF

30 GHz

300 GHz

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Electromagnetic spectrum

 shorter wavelengths       longer wavelengths 

Gamma rays  X-rays  Ultraviolet  Visible  Infrared  Terahertz radiation  Microwave  Radio

Visible (optical)

Violet  Blue  Green  Yellow  Orange  Red

Microwaves

W band  V band  Q band  Ka band  K band  Ku band  X band  S band  C band  L band

Radio

EHF  SHF  UHF  VHF  HF  MF  LF  VLF  ULF  SLF  ELF

Wavelength types

Microwave  Shortwave  Medium wave  Longwave

Categories: Radio frequency propagationHidden categories: Articles needing additional references from October 2009 | All articles needing additional references | All articles with unsourced statements | Articles with unsourced statements from February 2010 | All articles that may contain original research | Articles that may contain original research from February 2010

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Still, we know that the Sun’s rays, too much of them can cause sunburns, skin cancer, heat stroke, oxidized car finishes, and other challenges to our daily lives. Yes, those rays can also be converted into solar energy to power up our lights, television, computers, or recharge our iPhones – so it’s a good trade off. We pay attention and use prudence. But what happens when the Sun throws us a curve ball?

How so you ask? Well, what about solar flares, heat waves, and chaotic bursts during solar maximum phases? Sure, those are issues. Now what happens if this reliable Sun of ours, part of nature as we know it causes a solar flare so big it takes out our communication satellites, and electronics – not good right? Well, not long ago, our think tank was discussing this issue with a fellow think tanker type, Troy Laclaire.

Troy was worried about a solar flare taking out the FAA’s NextGen air traffic control satellite system, and stated; “Thinking more on this, I have to wonder, what is going to happen during a severe solar storm and satellites get knocked out?”

Well, that’s a good point and I like ITT Corporation as a company, one of the main makers of these computerized ATC systems. And yes, it’s nice of them to offer financing to airlines to upgrade their equipment to help with the NextGen ATC, but I agree, what good is such a system after an EMP weapon detonation, or massive solar flare.

The US Military Satellites are battle-hardened for solar flares, aviation communication satellite lesser so. This is a dangerous Billion financial fiasco waiting to happen, if these are not solar flare resistant systems. Basically it is not the next-generation, but the last-generation if it all collapses and goes dark one day, holy hell. I hope I’m not flying that day, or stuck at an airport. Troy commented; “I Really hope that they have a backup system.”

Well, the airplanes can all revert back to Unicom and the pilots announce their positions to each other, and then watch like a hawk for other traffic, and fly the proper routes, but it adds another layer of uncertainty, and guaranteed delays too. Troy stated; “I Think I would trust a ground based system a little bit better.” Indeed, but of course, that’s not always possible. The satellite system is better as long as it always works, but remember; security, and 100% up time is what we seek here right?

Mother Nature will do its thing, whether humans are here or not, and she doesn’t care if we build the sea walls high enough at our nuclear power plants by the sea, or our satellites strong enough to hold back the Sun’s rays. Indeed, I hope you will please consider all this.

Lance Winslow is the Founder of the Online Think Tank, a diverse group of achievers, experts, innovators, entrepreneurs, thinkers, futurists, academics, dreamers, leaders, and general all around brilliant minds. Lance Winslow hopes you’ve enjoyed today’s discussion and topic. http://www.WorldThinkTank.net – Have an important subject to discuss, contact Lance Winslow.

 

 


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