Lenticular Clouds

Found these on flickr:





Lenticular clouds mean severe turbulence and strong lift. Paragliders avoid them and the sky when they're present.

Power pilots tend to avoid flying near lenticular clouds because of the turbulence of the rotor systems that accompany them, but sailplane pilots actively seek them out. Although the clouds can produce heavy turbulence they also show a sign of precipitation. This is because the systems of atmospheric standing waves that cause "lennies" (as they are sometimes familiarly called) also involve large vertical air movements, and the precise location of the rising air mass is fairly easy to predict from the orientation of the clouds. "Wave lift" of this kind is often very smooth and strong, and enables gliders to soar to remarkable altitudes and great distances. The current gliding world records for both distance (over 3,000km) and altitude (14,938m) were set using such lift.