Editing Hang gliding (section)

== Soaring flight and cross-country flying ==
[[Image:GoldenMedows.jpg|thumb|Good gliding weather. Well formed [[cumulus cloud]]s with darker bases suggest active thermals and light winds.]]

A glider in flight is continuously descending, so to achieve an extended flight, the pilot must seek air currents rising faster than the sink rate of the glider. Selecting the sources of rising air currents is the skill that has to be mastered if the pilot wants to achieve flying long distances, known as [[Cross-country flying|cross-country]] (XC). Rising air masses derive from the following sources:<ref>{{cite book | last = Pagen | first = Dennis | title = Understanding the Sky - A Sport Pilot's Guide to Flying Conditions | publisher = Dennis Pagen | date = January 1992 | location = Mingoville, Pennsylvania, USA | pages = 280 | isbn =  978-0-936310-10-7   }}</ref>

'''Thermals'''
: The most commonly used source of lift is created by the Sun's energy heating the ground which in turn heats the air above it. This warm air rises in columns known as [[thermals]]. Soaring pilots quickly become aware of land features which can generate thermals and their trigger points downwind, because thermals have a surface tension with the ground and roll until hitting a trigger point. When the thermal lifts, the first indicator are the swooping birds feeding on the insects being carried aloft, or [[dust devil]]s or a change in wind direction as the air is pulled in below the thermal. An instrument developed by Frank Colver in the early 1970's specifically for hang gliders called the Colver Variometer made a very big difference as pilots were then able to HEAR when they were rising or at least descending slower. The variometer emitted a tone when it was turned on.  After  launch, as the sink rate increased, the instrument emitted a lower tone. As the sink rate decreased, the tone became higher, passing through the zero sink rate and then rising higher and higher as the rate of climb increased.  As the thermal climbs, bigger soaring birds indicate the thermal. The thermal rises until it either forms into a [[cumulus cloud]] or hits an inversion layer, which is where the surrounding air is becoming warmer with height, and stops the thermal developing into a cloud. Also, nearly every glider contains an instrument known as a [[variometer]] (a very sensitive vertical speed indicator) which shows visually (and often audibly) the presence of lift and sink. Having located a thermal, a glider pilot will circle within the area of rising air to gain height. In the case of a cloud street, thermals can line up with the wind, creating rows of thermals and sinking air. A pilot can use a cloud street to fly long straight-line distances by remaining in the row of rising air. 

; Ridge lift
: [[Ridge lift]] occurs when the wind encounters a mountain, cliff, hill, sand dune, or any other raised terrain. The air is pushed up the [[windward]] face of the mountain, creating lift. The area of lift extending from the ridge is called the lift band. Providing the air is rising faster than the gliders sink rate, gliders can soar and climb in the rising air by flying within the lift band parallel to the ridge. Ridge soaring is also known as [[slope soaring]].

; Mountain waves
: The third main type of lift used by glider pilots is the [[lee waves]] that occur near mountains. The obstruction to the airflow can generate [[standing wave]]s with alternating areas of lift and sink. The top of each wave peak is often marked by [[lenticular cloud]] formations.

; Convergence
: Another form of lift results from the [[Convergence zone|convergence]] of air masses, as with a [[Sea breeze|sea-breeze front]]. More exotic forms of lift are the polar vortices which the [[Perlan Project]] hopes to use to soar to great altitudes.<ref name="perlanproject">{{cite web|url=http://perlanproject.com|publisher=perlanproject.com|title=Home &#124; Perlan Project|access-date=30 April 2017}}</ref> A rare phenomenon known as [[Morning glory cloud|Morning Glory]] has also been used by glider pilots in Australia.<ref name="dropbears">{{cite web|url=http://www.dropbears.com/brough/index.html|publisher=dropbears.com|title=Morning Glory Clouds of the Gulf of Carpentaria &#124; A Guide to the Morning Glory|access-date=30 April 2017|url-status=live|archive-url=https://web.archive.org/web/20090720032625/http://www.dropbears.com/brough/index.html|archive-date=20 July 2009}}</ref>