SUNLIGHT AS A SOURCE OF llADIATION 117 



parent except for the complicated but slight absorption of water vapor. 

 The 9.()-M infrared band of ozone of the upper atmosphere is shown. At 

 14 n, a strong band of carbon dioxide sets in, and thereafter, for longer 

 wave lengths up to about 400 m, or 0.4 mm, water vapor is a strong 

 absorber with the exception of a narrow crevice of transmission at 22 ju. 

 In conclusion, it is apparent that the curves of Figs. 3-14 and 15 can be 

 used to make rough estimates, perhaps correct within a factor of 3, of 

 the solar energy in the infrared at the surface of the earth if the amount 

 of water vapor in the overhead atmosphere is known, but, if greater pre- 

 cision is required, provision must be made to measure the radiation 

 directly. 



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