REAL FUNCTION RelHum (T, P, R)
	
	implicit none

	real, intent(IN) :: T, P, R
	real :: Es, Rs
	
	! Calculate the saturation vapor pressure at this temperature
	Es = 6.111 * exp( (17.67*(T-273.15)) / ((T-273.15)+245.5) )
	! Calculate the saturation mixing ratio 
	Rs = 0.62 * Es / ( P - Es )
	! The relative humidity is a ratio of the given mixing ratio to saturation 
	RelHum = R / Rs * 100 

END FUNCTION RelHum