Question about the relative humidity formula?

Question

Is there any websites out there that have step by step examples of how to get the relative humidity? I've found some relative humidity calculators, but I have to learn how to get the answer manually.

Answer 1

RH= e(water vaopr pressure) divided by Es (saturated vapor pressure)

RH=e/Es

Answer 2

More simply put, with relative humidity you're looking at a ratio of how much water is actually in the atmosphere, compared to the maximum amount of water that the atmosphere could hold.

So the ratio looks like this: Actual H2O in Atmosphere/Max Possible H2O in Atmosphere.

You can look at a few different parameters to figure this out.You can use saturation vapor pressure, or mixing ratios, and I'm sure you can find a table of saturation vapor pressures and temperatures somewhere online.

So, say you're at 20 degrees, and you know what the current vapor pressure is. You go to your handy chart, look up 20 degrees, and find out what the associated vapor pressure is for that temperature. This value is the "maximum water vapor" that the atmosphere can hold at that temperature.

Then you just put the numbers together...how much water is actually in the atmosphere, divided by the maximum value that could be in the atmosphere. There's your ratio...and multiply by 100 to get your answer as a percent.

I hope this helps...