High-altitude clouds composed of ice crystals are called clouds.

High-altitude clouds composed of ice crystals are called cirriform clouds or the cirrus clouds. This is a type of cloud which is characterized by wispy, thin strands. This is the most common cloud formed at high-altitude. They have heights of greater than 6000 meters. These are made up of ice crystals which originated from supercooled water molecules. This type of cloud would foresee a fair weather or a pleasant weather. 

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