Middle level Clouds
Clouds in this group:
- Altostratus
- Altocumulus
Altostratus (As)
These clouds form in a uniform grayish or bluish sheet having very little texture. They are usually thicker, grayer, lower than cirrostratus, and is lighter in color than nimbostratus. The cloud sheet washes out the sky, often parts are thin enough to reveal the sun vaguely. Altostratus is caused by a large air mass that is lifted then condensed, usually by an incoming frontal system.
Altocumulus (Ac)
Altocumulus clouds form in white or graypatches, sheets, or layers and are composed of rounded element, generally with shading. Often they appear in wavelike arrangements, sometimes resembleming a honeycomb. occasionally, they are paertly fibrous or diffuse and may not be merged.Altocumulus clouds very seldom produce precipitation.
