Which cloud types are classified as high clouds?

• A. Cirrus, Cirrostratus, Cirrocumulus
• B. Alto-stratus, Alto-cumulus, Nimbostratus
• C. Cumulus, Stratus, Stratocumulus, Cumulonimbus
• D. Cirrus only

Answer: (A)

High clouds form in the upper part of the troposphere where temperatures are very cold, so they consist mainly of ice crystals rather than liquid water. This ice-crystal nature gives them thin, wispy or veil-like appearances. The three cloud types in this group—cirrus, cirrostratus, and cirrocumulus—are all found at high altitudes, typically above about 20,000 feet, which is why they’re classified as high clouds. They often indicate moisture and weather changes ahead in the upper atmosphere.

Mid-level clouds, marked by alto- prefixes, occur lower in the troposphere, roughly 6,500 to 20,000 feet, and are usually composed of liquid water droplets. The low-cloud types—cumulus, stratus, stratocumulus, and cumulonimbus—are generally found closer to the ground, with cumulonimbus capable of significant vertical growth but not classified as high clouds.