SVP and Temperature
¥As air parcel is lifted, it expands
¥decreasing its temperature,
decreasing its SVP
¥Also decreases water vapor density, VP and dew point
¥As a result, its relative humidity increases
¥If lifted high enough, RH=100% and cloud forms
¥Continued lifting causes more cooling
more water condenses out
Ahrens Fig. 4.5