PROPAGATIOS or ELFXIKIC W.illiS OVER THE EARTH 22!^ 



of MTN' heavy iims colliding wiili liglil lu-iilral molecules, r=o, since 

 6 = 1. I'or e(|iial masses & would lie about one half, hence r = .', mj. 



Since the resistance factor r is eciual to ;;//, in order to include the 

 i-lti'it of .iiii-iui.iiioii of the wave, we mii-ii icpl.Mc n li\- 



./ 



..(-.■:-) 



If, as usual, we assume a wave proportional in 



I c t ^ c ' 



the eiiuations (.')) show that, in ortler to calculate the \ahie of the 

 absorption constant k, we must put 



in which t is the generalized dielectric constant appropriate to the 

 case considered. We have worked out in this way the absorption 

 for the various cases treated above with the f(jllowing results. 



In the case in which there is either no magnetic field or the magnetic 

 held is parallel to the direction of the electric \ector, we find 



2no^ l+P/n"' 



This formula for absorption applies (for electrons) for any value 

 of / or H. Thus near the surface of the earth where the collision 



fretiuencv/ is of the order of 10", the fraction -^—will be large even for 



n 



rather short waves. As we go higher in the atmosphere this ratio 



decreases for a given wave frequency until at a height for which 



f 

 = 1 we encounter the ma.ximum absorption per electron. Above 



thi^. Ie\el ^^ and consequenth- the absorption per electron decreases. 



For ions other than electrons the resistance will be somewhat different 

 from mf, depending upon the ratio of the masses, and a corresponding 

 change must be made in the above statement. 



In this paper we are considering only the effects which take place 

 at heights above that for maximum absorption so that, generally 



speaking, ^ will be small or at least less than unity. This approxima- 

 tion will be used in computing the absorption constants which follow. 



