Cirrostratus clouds belong to the High Cloud (5000-13000m) group. They are sheetlike thin clouds that usually cover the entire sky.

The sun or moon can shine through cirrostratus clouds. Sometimes, the sun or moon will appear to have a halo around it when in the presence of cirrostratus. The ice crystals from the cloud refracts the light from the sun or moon, creating a halo. This halo is the width of your hand when you hold it out at arm's length.

Cirrostratus clouds usually come 12-24 hours before a rain or snow storm. This is especially true if Middle group clouds are associated with it.