Altostratus (from stratus, meaning layer) are middle level clouds, found at altitudes of 2,000 to 8,000 meters (6,500-26,000 feet). Usually gray or blue gray in color (these appear red due to the setting sun), they often cover the sky in dense sheets. Through thinner sections of the clouds, the sun or moon may appear as if seen through frosted glass. In the upper right is a deck of altocumulus clouds, which appear as a mass of small puffs, arranged in rows.
