Altostratus

urn:aero:airm:1.0.0:ConceptualModel:Subjects:Meteorology:Altostratus

Greyish or bluish cloud sheet or layer of striated, fibrous or uniform appearance, totally or partly covering the sky, and having parts thin enough to reveal the Sun at least vaguely, as through ground glass. Altostratus does not show halo phenomena.

Source: WMO International Meteorological Vocabulary,