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# Calculating Wet Bulb Temperature using Air Temp RH and Pressure

## Calculating Wet Bulb Temperature using Air Temp RH and Pressure

(OP)

First compute dewpoint temperature (Td)
Td = (-430.22+237.7*LN(E))/(-LN(E)+19.08) = Td in °C
E = (rH/100)*0.611*EXP(17.27*T/(T+237.3))

Then compute wet bulb temperature (Tw)
Tw = [(GAMMA*T)+(DELTA*Td)]/(GAMMA+DELTA)
GAMMA = 0.00066*P
where P is ambient barometric pressure in kPa
DELTA = 4098*E/(Td+237.3)2

I've been trying to find the combined measurement uncertainty when using this formula, particularly the sensitivity coefficients. Thanks

### RE: Calculating Wet Bulb Temperature using Air Temp RH and Pressure

Sensitivity coefficients?

Are you referring to the partial derivatives w.r.t. to particular parameters?

### RE: Calculating Wet Bulb Temperature using Air Temp RH and Pressure

(OP)
IRStuff

Yes, That is correct.

### RE: Calculating Wet Bulb Temperature using Air Temp RH and Pressure

So? You take the partial derivatives of the equation, in its unsimplified form.

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