[nim-boh-strey-tuh
s, -strat-uhs] 
| a cloud of a class characterized by a formless layer that is almost uniformly dark gray; a rain cloud of the layer type, of low altitude, usually below 8000 ft. (2440 m). |
| nim·bo·stra·tus (nĭm'bō-strā'təs, -strāt'əs) n. pl. nim·bo·stra·ti (-strā'tī, -strāt'ī) A low, gray, often dark cloud that precipitates rain, snow, or sleet. [nimb(us) + stratus.] |
| nimbostratus (nĭm'bō-strāt'əs) Pronunciation Key
Plural nimbostrati (nĭm'bō-strāt'ī') A dark, gray, mid-altitude cloud that often covers the entire sky and precipitates rain, snow, or sleet. Nimbostratus clouds generally form around 2,000 m (6,560 ft) but often extend to much higher and lower altitudes. See illustration at cloud. |