Can anyone give me a value for relative humidity formula for temp 0 to about 40 degrees celcius?

Question

Can anyone give me a value for relative humidity formula for temp 0 to about 40 degrees celcius?

Answer 1

jelly and custard...

Answer 2

Relative humidity from temperature and dewpoint;

If you know the temperature and the dewpoint, and want to obtain relative humidity, the formulas are as follows:

First, to convert the temperature and the dewpoint from Fahrenheit to Celsius, use the following formulas.

(3) Tc=5.0/9.0*(Tf-32.0)

(4) Tdc=5.0/9.0*(Tdf-32.0)

Tc=air temperature in degrees Celsius, Tf=air temperature in degrees Fahrenheit

Tdc=dewpoint temperature in degrees Celsius

Tdf=dewpoint temperature in degrees Fahrenheit

Note: If your temperature and dewpoint are already in degrees Celsius, you can skip the first step and proceed to the second.

The next set of formulas assumes a standard atmospheric pressure. These formulas will calculate saturation vapor pressure(Es) and actual vapor pressure(E) in millibars.

(5) Es=6.11*10.0**(7.5*Tc/(237.7+Tc))

(6) E=6.11*10.0**(7.5*Tdc/(237.7+Tdc))

Once you have the saturation vapor pressure and the actual vapor pressure, relative humidity can be computed by dividing the actual vapor pressure by the saturation vapor pressure and then multiplying by 100 to convert the quantity to a percent.

(7) Relative Humidity(RH) in percent =(E/Es)*100

For example, if you have a station report that included an air temperature of 85 degrees Fahrenheit and a dewpoint of 65 degrees Fahrenheit and you wanted to compute the relative humidity, you would proceed as follows.

First, convert the Fahrenheit values to Celsius using formulas (3) and (4). The values you get should be Tc=29.4 and Tdc=18.3

Next, calculate the saturation vapor pressure and the actual vapor pressure using formulas (5) and (6) respectively. The values you get should be Es=40.9 and E=21.0

Finally, calculate relative humidity using formula (7). The final answer should be RH=51.3 %(percent).

Note: Due to the rounding of decimal places, your answer may be slightly different from the above answer, but it should be within 2%.

Answer 3

I have to know what the dewpoint temperature is, the temperature at which the air is saturated.  Otherwise it cannot be determined, as any given temperature can have any relative humidity value from zero to 100% (I am ignoring super-saturation), depending on how much water vapor exists in the air.

Answer 4

Relative humidity of what?

The gas interaction between the liquid surface and air/gas makes a difference....