Monday, October 07, 2013-Stability is determined by comparing temperature of rising parcel to that of its surroundings (environment).By comparing lapse rate curves, 3 atmospheric conditions exist:1. Absolutely Stable Atmosphere2. Absolutely Unstable Atmosphere3. Conditionally Unstable AtmosphereAbsolutely Stable (Fig. 6.3)-exist when environmental lapse rate is less than moist adiabatic rate.-rising air parcel is always colder than air surrounding it.Conditions necessary to bring about a stable atmosphere:1. Warm air moving over cold surface.2. Nighttime radiational cooling.3. Advection of cold surface air.Absolutely Unstable (Fig. 6.8)-occurs when environmental lapse rate is greater than dry adiabatic rate.-rising air is always warmer than air surrounding it.Conditions necessary to bring about an unstable atmosphere:1. Cold air moving over warm surface.2. Daytime solar heating of the surface.3. Radiational cooling of clouds (loss of heat energy to space from clouds).Conditionally Unstable (Fig. 6.9)-Occurs when environmental lapse rate is between the moist adiabatic lapse rate and the dry adiabatic lapse rate.-Atmosphere is stable if rising air is unsaturated, but unstable if rising air is saturated.Stable Atmosphere:-Clouds are widespread.-Precipitation, if any, is light to moderate.-Most associated with fair weather.Unstable Atmosphere:-Clouds are towering.-Heavy precipitation.-Can be associated with severe