Nimbostratus (Ns)
Nimbostratus (Ns) (latin "Rain Cloud layer") This cloud is a thick layer cloud from which rain or snow falls. It often forms from thickening altostratus near a weather front. The cloud looks dark grey/black from below but can seem to intensify as rain falls, The break up of the cloud forms Fractostratus (St fra) a ragged shredding of the clouds structure.