Face -lifting: While lifting, a sample of unsaturated air is cooled adiabatically by expansion at the rate of about 5°F. per thousand feet. The cooling steadily decreases the sample's capacity for water vapor so that if the lifting is sufficient the initially unsaturated sample finally becomes saturated. Further lifting beyond this condensation level of the sample produces additional cooling with resultant condensation of the amount of moisture in excess of that which the temperature permits to remain in the gaseous state.
Domes are formed by the lifting of strata, as when granitic magma is intruded. As the lifting increases the surface -lifting is worn away by erosion and underlying Granite is exposed. When such domes are large and high they constitute true dome mountains, such as the Black Hills of Dakota.
Lifting of a saturated air sample pro cooling at a rate less rapid than that fo: saturated air because of the heat of conden: released with transformation of moisture the gaseous to the liquid state. Further trar mation to the solid state provides an addi source of heat. The lifting will continue as as the sample's temperature continues to be gi than that of its surroundings. It is thus ev other factors being equal, that the different of cooling favor greater lifting of a saru than of an unsaturated sample. If the em ment temperature is stratified so that wan overlies cold air, samples of air rising from the ground may eventually reach a level i they become cooler than their surroundings, ing above the critical level is halted. This becomes the top of a cloud deck when the i air samples beneath it reach saturation d their ascending motions.
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Photography
