Vertical Changes 135 



earth's surface is shown in Fig. 5.3. It will be seen that about half of 

 the solar radiation is in the infrared region and this represents a di- 

 rect supply of heat. The visible and ultraviolet portions of the sun's 

 emission will also produce a heating effect after they have become 

 absorbed. The sample calculations in Table 7 illustrate the relative 

 absorption of the various parts of the spectrum by air and water. 



3000 5000 7000 9000 11,000 13,000 15,000 17,000 19,000 A 

 Wavelength 



Data jiom Fowie, 1927 

 Fig. 5.3. Spectral distribution of solar energy at the earth's surface, showing the 

 ultraviolet (UV), visible (divided into color components), and infrared portions. 



TABLE 7 



Comparison of Relative Absorption of Sun's Radiation by Air and 



Water 



Outside atmosphere 



Mt. Whitney, California 93 



(summit 4420 m) 



Sea level 75 



2 m below surface 71 



30 m below surface 17 

 (clearest ocean water) 



97 



20 



70 



98 



