F. W. Very — Note on Atmospheric Radiation. 533 



Art. XLYI. — Note on Atmospheric Radiation ; by Frank 



W. Very. 



The heat which gives to any layer of the atmosphere its 

 observed temperature is derived from several sources which 

 may be designated as follows : 



+ h c = heat transferred by convection from warmer and lower 

 layers of air. 



+ /;,, = heat transferred by molecular penetration from warmer 

 neighboring air masses in any direction. 



+ h w = heat derived from the condensation of aqueous vapor. 



-f h s = heat from absorption of solar radiation hy the molecules 

 of gases and vapors, or by floating dust from which it is 

 transferred to gaseous molecules. 



+ //, = heat from a similar absorption of terrestrial radiation. 



+ A„ = heat produced by absorption of radiation from warmer 

 air masses, situated either above or below, but usually 

 below. Here each atmospheric ingredient absorbs selec- 

 tively and solely the radiations of those special wave- 

 lengths which it can itself emit. 



± h t = heat from chemical changes, such as ionization by solar 

 ultra-violet radiation. The heat produced in this way may 

 be included 'under the heat (h s ) from absorption of the 

 ■ sun's rays. The direct effect of ionization on temperature 

 is probably small, but it may have important secondary 

 consequences through the production of peculiar substances 

 in small amount, but possessing extraordinary powers of 

 selective radiant absorption and emission. 



± h q = heat imported, or abstracted by the planetary atmospheric 

 circulation. 



The relative importance of these sources of thermal supply 

 varies greatly at different elevations. In the isothermal layer 

 (3), the heat received is 



H, = h s + h, + h 9 ± h v 



Convection may not have ceased entirely, but it is very small, 

 and has been omitted from the expression. There are no 

 clouds here and terrestrial radiation passes through unchanged, 

 having suffered all the absorption of which it is capable in 

 lower layers. The heat from absorption of solar rays becomes 

 exceptionally powerful where the solar radiation first enters 

 the aqueous atmosphere in the higher levels of the isothermal 

 layer. 



Between the isothermal layer and the air near the ground 

 lies the great body of the cloud-producing atmosphere (2), 

 where 



H„ = h c + h s + h„ + h s + K + h t ± h v 



