Lenticular (lens-shaped) clouds indicate an atmospheric wave condition, where the wind follows an up and down path, often in the downwind side of mountains. Pilots know that this condition and the appearance of lenticular clouds means there is a very high likelihood of moderate to severe to extreme turbulence in the area.
This particular cloud seen here was west of Point Vicente on the California Coast in October after some rain moved through the area. Click on the image for a larger view.
