Roy Jenne
								May 1980


			Some Moisture Calculations


 1.  Vapor pressure (ED):

			     dew point temperature in degrees C.
			    /
     ED = 6.1078 * 10 ** ((TD * A)/(TD + B)) in mbs

 2.  Saturated vapor pressure (ES):


     ES = 6.1078 * 10 ** ((T * A)/(T + B))
			    \
			     temperature


		 A =   7.5 }  for use in
		 B = 237.3 }  vapor pressure with respect to water

		 * A =   9.5 } for use in vapor pressure
		   B = 265.5 } with respect to ice

 3.  Relative humidity = 100 * ED/ES

 4.  Absolute virtual temperature (TV):

				 vapor pressure
				/
     TV = (T + 273.15)/(1-.379*ED/Press)
				    \
				     total pressure

 5.  Mixing ratio (W):

				 vapor pressure
				/
			.62197 e                        grams water
		    W = ________                        ___________
			   P - e                        grams dry air
			    \                              |
			     total pressure                |
						     Thus 12 g/Kg comes out
						     as .012

 6.  Wet Bulb
     Vapor Pressure
     Dew Point               (P365, Smithsonian for first part)

     Ew - E
     ______      = .000660 (1 + .00115 T )
     Press (T-Tw)                       w

 Therefore:

	    E = Ew - Press (T-T ) (.000660) (1 + .00115 T )
			       w                        w
	   Tw = Wet bulb temperature (degrees C.)
	   Ew = Saturated vapor pressure at temperature Tw
	    E = Vapor pressure in air
	Press = Total barometric pressure (units same as Ew, E)
	    T = Air temperature (degrees C.)

 E is the vapor pressure in the air, which is the vapor pressure at the
 dew point temperature.  To solve for the dew point temperature, use the
 formula:

	    E = 6.1078 * 10 ** ((TD * A)/(TD + B)) in mbs

		 let C = log   (E/6.1078)
			    10

 Then:

	    C T  + C B = A T
	       d            d

		    B C
		    ___     Dew point in degrees C
	       T =  A-C
		d                          where A =   7.5
						 B = 237.3