Middle clouds: Altostratus 1

Illustration of a cloud belonging to a class characterized by globular masses or rolls in layers or patches. Alto, "high", cumulus, "heaped". Usually white or gray, and often occurs in sheets or patches with wavy, rounded masses or rolls. Often are seen preceding a cold front, and their presence on a warm, humid, summer morning frequently signals the development of thunderstorms later in the day

Illustration of a nimbostratus cloud, a rain cloud characterized by a formless layer that is almost uniformly dark gray, of medium altitude, usually developing above 6500 ft (2000 m). Nimbo is from the Latin word "nimbus" meaning rain. They may block a great amount of sunlight as a result of their characteristic dense structure

Illustration of clouds with rain falling down

Illustration of a cloud with rain droplets falling straight down

Illustration of a cloud blowing air symbolizing wind

Illustration of a cloud with sheeting rain, coming down hard and slanted

Illustration of a cirrocumulus cloud, a large, white patch or tuft without a gray shadow. Composed of supercooled liquid droplets (if they freeze, becomes cirrostratus - cirrocumuli are short lived) Each cloudlet appears no larger than a finger held at arms length. It occurs in patches or sheets, organized in rows like other cumulus, but since they are so small, cirrocumulus patches take on a finer appearance, sometimes referred to colloquially as "herringbone" or "mackerel"

Illustration of wind flow