We get a lot of lenicular clouds along the Rocky Mountain front range, but I've never seen anything like the ones in those photos.

Lenicular clouds are very important to watch out for if you're a pilot. They indicate very heavy turbulence. Sailplane pilots love them, though, because they indicate that mountain wave conditions exist. Waves are like the ripples in a stream as the water flows over a rock. The vertical speeds can get very high, but if you're looking to go high in a sailplane, waves are the ticket. The world sailplane altitude record is over 40,000 feet and was set in wave conditions. Aviation adventurer Steve Fossett hopes to shatter that record, eventually going as high as 100,000 feet!