Nimbostratus, unlike cumulonimbus, is not associated with thunderstorms, however at an unusually unstable warm front caused as a result of the advancing warm air being hot, humid and unstable, cumulonimbus clouds may be embedded within the usual nimbostratus.
42.
Nimbostratus, unlike cumulonimbus, is not associated with thunderstorms, however at an unusually unstable warm front caused as a result of the advancing warm air being hot, humid and unstable, cumulonimbus clouds may be embedded within the usual nimbostratus.
43.
Classifications that follow this approach usually show nimbostratus either as " low-�tage " to denote its normal base height range, or as " middle-etage " based on the altitude range at which it normally forms.
44.
The two genera that are strictly low-�tage are cumulonimbus, which along with nimbostratus, are often classified separately as clouds of vertical development, especially when their tops are high enough to be composed of super-cooled water droplets or ice crystals.
45.
In comparison, " regular " clouds-- like the wispy high flying cirrus and cirrostratus, or the low hanging nimbostratus and stratocumulus-- form within a moisture-laden zone that exists from several hundred feet up to 6 miles from the surface.
46.
"' Nimbostratus "'is a former " Family C " low-level stratiform genus that is now classified by the World Meteorological Organization ( WMO ) as a " vertical " or " multi-level " stratus type because it forms in the middle level or " �tage " of the troposphere and usually spreads vertically into the low and high �tages.
