Which lower level of clouds are commonly called "rain clouds?"

DerekT

Stratus Cumulus Nimbus Dec 30 03, 3:09 PM

McGruff

Only some types of clouds produce rain, including nimbostratus and cumulus clouds. http://yahooligans.yahoo.com/content/ask_earl/20020904.html Luke Howard believed all clouds belonged to three groups: cumulus, stratus and cirrus. Cumulus (Latin for heap) clouds grow upward in the sky. The puffy clouds we see on fair weather days are cumulus ones, but clouds that produce showers and thunderstorms are, too. Stratus (Latin for layer) clouds extend in all directions for a good distance. They typically are not very deep (only a few hundred to a few thousand feet) and can be just sun blockers or produce rain or snow. Cirrus (Latin for hair or fiber) clouds are the wispy ones high in the sky. Almost always made of ice crystals instead of water droplets, they never produce rain or snow. Howard realized the delineation between a cloud that produces rain or snow and one that does not is important, so the word nimbus (Latin for rain) was added to those clouds that precipitate. A thunderstorm cloud, therefore, is a cumulonimbus cloud, and overcast skies that produce rain or snow are nimbostratus clouds. http://www.whiotv.com/weather/2451529/detail.html">www.whiotv.com/weather/2451529/detail.html Jan 10 04, 8:28 PM