NIMBOSTRATUS
This cloud exhibits a combination of rain or snow, and sometimes the base of the cloud cannot be seen because of the heaviness of precipitation. They are generally associated with fall and winter conditions, but can occur during any season.
Gray, dark clouds with no clearly defined base which are associated with continuous precipitation that may or may not reach the ground. The clouds are several thousand feet thick and will completely block the Sun. Their precipitation may consist of snow, sleet, rain, or drizzle, but not hail (since there is no convection). [See also stratus.]
