256 Tables 57—62 



RELATION BETWEEN PRESSURE CHANGE AND GEOPOTENTIAL CHANGE 



From the hydrostatic equation and the definition of geopontential 1 



d* = -RV.& (1) 



where 



P 



$= geopotential, 

 R = gas constant for dry air, 

 T'v = adjusted virtual temperature of the air, °K. (see Table 72), 

 p = pressure, 



or dp = ^M* (2) 



Tables 57-62 give solutions to equations (1) and (2) for various combinations of units 

 as indicated below: 



A. Change in geopotential corresponding to a given change in pressure 



Unit of geopotential a Unit of pressure Temperature scale 



Equations (1) and (2) take the following forms for the various tables: 



Table 57, d* = - 29.2898 T'v/p gpm. 

 Table 58, d# = - 96.0951 T'v/p gpft. 

 Table 59, d* = — 9.60951 T' v /p gpft. 

 Table 60, dp = — 0.341416 p/V, mb. 

 Table 61, dp — — 0.1040635 p/V, mb. 

 Table 62, dp — — 0.1040635 p/T'v in. Hg. 



Note. — T'v must be expressed in °K. in the above formulas. 



1 See Table 49 for definition of geopotential. 



' 1 geopotential foot (gpft.) = 0.3048 geopotential meter (gpm.). 



SMITHSONIAN METEOROLOGICAL TABLES 



