Table 113 (concluded) 



395 



VISCOSITY AND THERMAL CONDUCTIVITY OF AIR AND DIFFUSIVITY OF 



WATER VAPOR IN AIR 



For gases the dependence of diffusivity on pressure and temperature is represented by 4 



D_( T\ n & 

 D -\To) p 



where Do is the diffusivity at absolute temperature To and pressure po. Schirmer B gives 

 n = 1.81 and the value of D at °C, the values at other temperature have been computed 

 from the kinematic viscosity, to which they are proportional. 



Thermo- Diffusivity 

 Kinematic metric con- of water 

 viscosity ductivity vapor in air 



4 Boynton, W. P., and Brattain, W. H., Interdiffusion of gases and vapors. International Critical 

 Tables, vol. 5, pp. 62-63, McGraw-Hill Book Co., New York, 1929. 



5 Schirmer, Robert, Die Diffusionszahl von Wasserdamf-Luft-Gemischen und die Verdampfungsge- 

 schwindigkeit. Zeitschr. Ver. deutsch. Ing., Beihefte Verfahrenstecknik, Heft 6, pp. 170-177, 1938. 



SMITHSONIAN METEOROLOGICAL TABLES 



