The Difference in Dewpoint Versus Humidity

[artist]

Can someone explain the differences between dewpoint and humidity, please?

[pojo]

RH: A measure of the actual amount of water vapor in the air compared to the total amount of vapor that can exist in the air at its current temperature

DP: Provides a measure of the actual amount of water vapor in the air, is the temperature to which the air must be cooled in order for that air to be saturated.

Shannon

[Chacor]

What's the mathematical relationship between the two and current temperature? I know it but can't remember offhand.

[wjs3]

Here you go:

http://www.gorhamschaffler.com/humidity_formulas.htm

WJS3

[artist]

thank you everyone!

[jeff]

Dewpoint and PW is a much better measure of atmosphric moisture compared to humidity. Due tot he math relationship as the temp. rises the RH will fall if the dewpoint stay constant. So even with a muggy dewpoint of 72 and temp of 93 the RH may only be in the 40-50% range...which does not sound very humid...but it is.

[Aslkahuna]

With a temperature of 110F and a dewpoint of 72F (which can happen at Phoenix during the monsoon) the humidity would be even lower (in the 20-30% range) leading to claims on TWC that it was a Dry Heat.

Steve