While clouds appear in infinite shapes and sizes they fall into some basic forms. From his Essay of the Modifications of Clouds (1803) Luke Howard divided clouds into three categories; cirrus, cumulus and stratus. The Latin word ‘cirro’ means curl of hair.

What are the 3 middle clouds?

High clouds (cirrus, cirrocumulus, cirrostratus) observed over the middle latitudes typically reside at altitudes near and above 20,000 feet. At such rarefied altitudes, high clouds are composed of ice crystals. Middle clouds (altostratus, altocumulus) reside at an average altitude of ~10,000 feet.

What are nimbus clouds?

Nimbostratus clouds are dark, grey, featureless layers of cloud, thick enough to block out the Sun. Producing persistent rain, these clouds are often associated with frontal systems provided by mid-latitude cyclones.