Altostratus is a greyish or bluish cloud sheet or layer of striated, fibrous or uniform appearance which totally or partly covers the sky, but having parts thin enough to reveal the sun at least vaguely, as through ground glass.  No halo.

Altostratus is composed of water droplets and ice crystals and contains raindrops and snowflakes. It is generally so dense that the sun can only be seen vaguely.