M1 Clouds: Thin altostratus (As)
Altostratus, the greater part of which is semi-transparent; through which the sun or moon may be weakly visible as through ground glass.

Additional Views:




Notes: Thin altostratus usually evolves from the gradual thickening of a veil of cirrostratus. This means that unlike most clouds which increase in height as they grow, altostratus (and nimbostratus) grow as the base of the cloud lowers.
Altostratus is grayish or bluish color, never white, and the greater part is always translucent enough to reveal the sun (or moon) as through ground glass. Objects on the ground do not cast shadows, and halo phenomena are never seen.
