At what altitude is a high cloud classified?

High clouds are classified as those that form at altitudes above 20,000 feet. This classification encompasses the cirrus types of clouds, such as cirrus, cirrostratus, and cirrocumulus, which form at these higher elevations in the atmosphere. These clouds typically consist of ice crystals due to the lower temperatures found at such heights.

The significance of understanding cloud classifications involves their implications for aviation operations and weather patterns. High clouds generally indicate fair weather, but they can also signal changes in the atmosphere that may lead to weather events such as storms, especially if they start to thicken or lower. Recognizing that high clouds occur above 20,000 feet allows pilots to anticipate and navigate weather conditions effectively while in flight.