If the glide ratio were the only factor involved, gliders would not be able to stay in the air nearly as long as they do. The key to staying in the air for longer periods of time is to get some help from Mother Nature whenever possible. The same thing works with gliders. If you are descending at one meter per second, but the air around the plane is rising at two meters per second, you're actually gaining altitude. As the air near the ground is heated by the sun, it expands and rises.
Pilots keep an eye out for terrain that absorbs the morning sun more rapidly than surrounding areas.
These areas, such as asphalt parking lots, dark plowed fields and rocky terrain, are a great way to find thermal columns. Pilots also keep a look out for newly forming cumulus clouds, or even large birds soaring without flapping their wings, which can also be signs of thermal activity. Once a thermal is located, pilots will turn back and circle within the column until they reach their desired altitude at which time they will exit and resume their flight. To prevent confusion, gliders all circle in the same direction within thermals. Ridge Lift Ridge lift is created by winds blowing against mountains, hills or other ridges.