What characterizes a cap cloud?

A cap cloud is distinctively known for its lens-shaped appearance, particularly when it forms over mountain peaks or ridges. This phenomenon occurs when moist air is forced to ascend over higher terrain, causing it to cool and condense into a cloud. The resulting cloud can form a characteristic cap or hood shape that clings to the top of the mountain.

The formation process of a cap cloud typically involves specific atmospheric conditions, where stable and humid air flows over elevated terrain. This leads to orographic lift, which is essential for the development of this type of cloud. The lens shape results from the way the air flow interacts with the mountain, often appearing smooth and stretched out like a cap.

While a cap cloud can develop in association with weather phenomena, such as thunderstorms or other storm systems, it is not limited to those circumstances and does not typically form at the base of thunderstorms nor is it directly linked to tornadoes. Thin, wispy clouds at high altitudes usually refer to cirrus clouds, which are quite different in both formation and appearance, further distinguishing them from a cap cloud.