primary process for forming rain in the middle and high latitudes and the only process to form snow; needs freezing nuclei to initiate water freezing; requires supersaturated conditions (RH>100%)
primary process in tropics for randrop formation and in mid-latitudes during the summer
nimbostratus and cumulonimbus
large cumulonimbus clouds
Sub-Tropical High pressure cells
immense body of air with homogenuous physical properties
area in which air masses originate
arctic basin and Greenland (stable) - bitterly cold/dry
Interior Canada and Alaska (stable) - cold/dry
norther interior Mexico and SW United States (unstable) - hot/dry
norther pacific and atlantic (stable summer) - cool/humid
Gulf of Mexico, Caribbean - warm/humid
boudary separating air masses of different densities
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