Nimbostratus (Ns)

Type: Medium-level cloud

Height of cloud base: 1,500-10,000 ft

Cloud colour: Dark grey.

Cloud shape: A thick, diffuse layer covering all or most of the sky.

Other cloud features: Sun or moon always blotted out. Accompanied by moderate or heavy rain or snow, occasionally ice pellets. Although classed as a medium cloud, its base frequently descends to low cloud levels. May be partly or even totally obscured by stratus forming underneath in precipitation.