Buck 1011C, Руководство по эксплуатации

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APPENDIX 1: HUMIDITY CONVERSION EQUATIONS
(Revised 7/96)
Computer-efficient algorithms for converting among several humidity units, as used in HCON,
are given here. They utilize vapor pressure formulations developed by A. Buck (1981).
DP = dew or frost point in deg C
e = vapor pressure in millibars
es = saturation vapor pressure in millibars
P = pressure in millibars
r = mixing ratio by weight in ppm
RH = relative humidity in percent
rho = absolute humidity in g/m3
rhos = absolute humidity at saturation
T = temperature in deg C
Tk = absolute temperature in K
Saturation vapor pressure (es) = f1(T) = e/RH
Dew/frost
point (DP) = f2(e) (e)
= f2[r x P/(622 x 103 + r] (r)
= f2(RH x f1(T)/100) (RH)
= f2(rho x Tk/216.7) (rho)
Vapor pressure (e) = f1(DP) (DP)
= r x P/(622 x 103 + r) (r)
= RH x f1(T)/100 (RH)
= rho x Tk/216.7 (rho)
Mixing ratio (r), ppmw = (18.02/ M.W. of gas) x 106 x e/(P-e) (e)
= (18.02/ M.W. of gas) x 106 x f1(DP)/[P - f1(DP)] (DP)
= (18.02/ M.W. of gas) x 106x RH x es/(100 x P - RH x es) (RH)
= (18.02/ M.W. of gas) x 106 x rho x Tk/(216.7 x P - rho x Tk) (rho)
Relative humidity (RH) = 100 x f1(DP)/f1(T) (DP)
= 100 x e/es (e)
= 100 x r x P/[(6 r) x es] (r)
= 100 x rho x Tk/(216.7 x es) (rho)
Absolute humidity (rho)= 216.7 x f1(DP)/Tk (DP)
= 216.7 x e/Tk (e)
= 0.2167 x r x P/[(622 + .001 x r) x Tk] (r)
= 216.7 x RH x es/(100 x Tk) (RH)
mixing ratio by volume (ppmv) = mixing ratio by weight (ppmw) x (M.W. of gas)/ 18.02
grains/lb = r x 0.007
Precipitable cm per km = rho/10