Dew Point Temperature Question?

Question

What happens to the dew point temperature of a descending mass of air

Answer 1

Unless it mixes with another air mass its dewpoint temperature remains unchanged.  The relative humidity, however, increases until the dewpoint temperature is reached.

Answer 2

I agree with Pegminer.

The Santa Ana winds are a hot dry wind caused by descending air out of the high desert. It is warmed partially by compression as the air descends lower in the atmosphere and with warming, the RH decreases since it dependent on temperature. Thus the hot dry wind.  

The dew point is pretty much unchanged. It could be argued that it does change slightly due to pressure considerations but this is generally considered insignificant in comparison to the addition or subtraction of the amount of water vapor in the air mass.

Answer 3

2nd answer is correct, descending air, such as that on the leeward side of a mountain is warming and contracting as to heat up the airmass.  This would cause the RH of the parcel to drop as the temp is increased but dewpoint constant.

Answer 4

Let me explain it this way.  As the temperature falls it reaches it saturation point.  That is the dewpoint.    If I had a temperature of 52 and a dewpoint of 52,   I would have a 100% relative humidity.   Dewpoint is relative to the temperature, so a high pressure system could actually dry out that dewpoint temperature relative to the true temperature as it falls.   That is why you see a temperature of like 52 and a dewpoint of let's say 36 because that parcel of air is drying out.   It would then have to get down to 36, to product visible water vapor.

Answer 5

I would agree with Helmut that the dewpoint remains constant, but I think the relative humidity should go down, not up.