Air reaches dew point at what temp...and starts cooling at the rate of ....per 1,000 ft. ?

Answer 1

Dew point is determined by local humidity.
At least do enough of your reading to ask
a sensible question.

Answer 2

The old professor says: A simple sounding question with a very complex answer. The dew point is defined as that temperature at which the relative humidity of the parcel of air reaches 100%. This temperature depends on the absolute humidity...or how much moisture there is in the air to begin with. The more you start with, the higher will be the dew point temp.

The rate of cooling of an air mass as it ascends through the atmosphere is defined in two environs. The dry adiabatic lapse rate (the temp drop of DRY air per 1000 ft) differs from that of the wet adiabatic lapse rate (the temp drop of humid air per 1000 ft). The rate of temp drop with altitude changes, since a relativly dry air mass closes in on the dew point temp as it cools with increasing altitude. When the dew point is reached and precipitation begins, the moisture is lost and the dew point drops, causing the adiabatic lapse rate to be modified yet again. This is now called the saturation lapse rate and is about 2.7 degrees F. per 1000 ft.