The cirrostratus is one the high cloud. They are distributed above 6000 meters in height. They have a bright white and transparent appearance. They can cover the whole sky or part of the sky. The sun or moon can be clearly seen through the clouds. They are composed of ice crystals. When light penetrates and refractions, it can produce solar halo or moon halo, which is also a sign of the difference between cirrostratus and other cloud genus.