CIRRUS clouds are the highest of all the normal clouds we see in the sky. Their altitudes range from near ground level (in very high latitudes) to 30,000 feet in more temperate regions. Cirrus clouds are composed of ice crystal that form directly from the vapor state at very low temperatures.
WIND SWEPT CIRRUS - This image shows a
trailing shower of ice crystals. As the cirrus ice crystals form and grow,
their increasing weight allows them to fall through the atmosphere. In all
but the polar regions, these crystals seldom survive to the Earth's
surface. Instead, as shown here, the ice crystals fall into warmer air
where they simply sublimate back into the vapor state.
High altitude CIRRUS
Precipitating CIRRUS
Wind swept cirrus in Maricopa County, AZ. Foreground plants are agave
(inflorescence) and the tips of an ocotillo.
Red sunsets and blue sky during a sunset over the White Tank Mtns in western
Maricopa County, AZ.