Temp/Dewpoint Spread and Relative Humidity

[skeezer]

Here is my question. Does anyone know how to convert the temp/dewpoint spread into the relative humidity (you know 80%, 70%, etc.)?

I was wondering because the dewpoint spread is nice to know when thinking about the possibility of fog, but what I really want to know is if I will be sweating like a pig by the time I step off the aircraft stairs.

Thanks in advance

Peace Out

Skeezer

 

[Lrjtcaptain]

Well, its not just that simple. You would need to use a chart.
Reason being is you need to know the vapor pressure for a current temperature. That would give you the maximum possible value. Then using the dew point, you see how far apart the two numbers, which make the air evaporate better...hence lower relative humidity.

Your best bet is get an electronic E6B. That has the tables already in there and will calculate them.

Call the NWS, they may have some easy way of doing it but I know that it isn't the easiest number to come up with.