Clouds, Cirrus

CIRRUS CLOUDS ARE the thin and wisp-like clouds seen at high altitudes (higher than 20,000 to 26,000 ft., or 6,000 to 8,000 m.). The name cirrus comes from the Latin word for curl. They are composed predominantly of tiny ice crystals, because they form in the cold region of the troposphere. If cirrus clouds drop their ice crystals, these crystals evaporate before they arrive at the ground.

Cirrus clouds can take on a variety of formations, including a more tuft-like characteristic called cirrocumulus, which also include supercooled water droplets. Some cirrus clouds are called cirrostratus; this [Page 255]type of cloud formation occurs when the thin strands of clouds are so dense that they cannot be deciphered. Other formations include cirrus aviaticus (also called contrails, the artificial ...