Nimbostratus

A Nimbostratus is a cloud of the class characterized by a formless layer that is almost uniformly dark gray; a rain cloud of the layer type, of low altitude, usually below 8000 ft (2400 m).

External Links

• National Science Digital Library - Nimbostratus (http://www.nsdl.arm.gov/Library/glossary.shtml#Nimbostratus)