Table 79 



PSEUDOADIABATIC LAPSE RATE 



Water stage 



323 



The pseudoadiabatic equation for the water stage recommended by the Aerological 

 Commission of the International Meteorological Organization (Toronto, 1947) is 



(c, + r v c w )dT/T - Rdp'/P' + d(r a L v /T) = 

 where : 



c p = specific heat of dry air at constant pressure (work units), 

 c« = specific heat of liquid water (work units), 

 i? = gas constant for dry air (work units), 

 L v = latent heat of vaporization of water (work units), 

 r» = mixing ratio at saturation with respect to water, 

 p' = partial pressure of dry air, 

 T = absolute temperature. 



Upon introducing the hydrostatic equation and the definition of geopotential, 

 dT/d4> = - Y/X °C./100 gpm.* 

 where : 



$ = geopotential, 



Y = 9 8 X 10 8 (^ + r< °) (-^^ + ruLy) 



d loge e v 



RT 



X = c p + r v [~c. + dWldT - L v /T + 1/k d l °f£ Cw (RT + r v L, + kL v ) J , 



k = ratio of the molecular weight of water vapor to that of dry air = 0.62197, 

 e» := saturation vapor pressure over water. 



In performing the computations a constant value of c p = 1.005 X 10 T erg. g." 1 "K." 1 was 

 assumed. 



50 0.271 0.267 0.263 0.259 



* Harrison, L. P., unpublished manuscript, 1948. 



SMITHSONIAN METEOROLOGICAL TABLES 



