The world Meteorological Organization describes stratocumulus clouds as grey or whitish, or both grey and whitish, patch, sheet or layer of cloud which almost always has dark parts, composed of rounded masses, rolls, etc, which may or may not be merged. 

Stratocumulus is composed of water droplets, sometimes accompanied by raindrops or snow pellets and more rarely by snow crystals and snowflakes.

Stratocumulus may, in cold weather, produce virga.

In the tropics it is sometimes observed in the form of a long roll (roll cloud) or an elongated lens-shaped wave cloud, or in the form of turrets rising from a common horizontal base.