324 Table 80 



PSEUDOADIABATIC LAPSE RATE 



Ice stage 



The pseudoadiabatic equation for the ice stage recommended by the Aerological Com- 

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



(c P + nc t )dT/T - Rdp'/p' + d(riL./T) = 

 where : 



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

 d = specific heat of ice (work units), 

 R = gas constant for dry air (work units), 

 L, = latent heat of sublimation (work units), 

 r< = mixing ratio at saturation with respect to ice, 

 P' — partial pressure of dry air, 

 T = absolute temperature. 



Upon introducing the hydrostatic equation and the definition of geopotential, 



dT/d* = - Y/X °C./100 gpm.* 

 where : 



$ = geopotential, 



Y = 9 8 X 10 s + r< ) (RT + fiL,) 

 RT 



X = c P + r t la + dL./dT - L./T + l/k d X( f« Ci (RT + nL, + H..) 1 , 



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

 e< = saturation vapor pressure over ice. 



In performing the computations a constant value of c p = 1.005 X 10 T erg. g." 1 C K. _1 was 

 assumed. 



SMITHSONIAN METEOROLOGICAL TABLES 



