THE SUN AND THE ATMOSPHERE STETSON 163 



Could we visualize the ethereal substance of the ionosphere as we 

 visualize the surface of the ocean, we should find times when terrific 

 storms were raging in this ionosphere. Here ions and electrons are 

 being hurled hither and yon as though some great electrical wind 

 played upon its surface, creating waves literally miles high. Fre- 

 quently the turbulence attains such proportions that no reflecting 

 surface for radio communication seems possible at all. When dis- 

 turbances on the sun subside, the undulations in the ionosphere may 

 quiet down and there is a return to more normal conditions for com- 

 munication traffic through this ocean of the upper air. 



While knowledge of the sun has helped us to understand the 

 vagaries of radio, we are coming to see that radio is one of the most 

 important tools for learning about what happens on the sun and how 

 disturbances there affect the ions in this upper air. Perhaps some 

 day, even though the sky is cloudy, we shall have a sufficient number 

 of reports of radio conditions over the globe so that we can form a 

 very good idea as to what is happening on the surface of the sun by the 

 way in which world-wide radio communication behaves. Unlike the 

 telescope, radio apparatus does not go out of commission when the 

 sky is overcast, for electric waves, of course, pass through the clouds 

 as easily as ordinary daylight comes through window glass. 



Concerning the exact method or methods by means of which the 

 sun produces all these electric disturbances of the upper air with the 

 concomitant magnetic variations in the earth, we still lack a great 

 deal of knowledge. The fact that the ultraviolet radiation from the 

 sun is the major factor in producing this ionization appears a reason- 

 able assumption. Whether or not in addition to the effect of the 

 ultraviolet light, streams of charged particles also emanate from the 

 sun in the regions of sunspots is perhaps still debatable. The elab- 

 orate mathematical work of Dr. Stormer, in calculating the movements 

 of hypothetical charged particles from the sun striking the upper 

 atmosphere of the earth and thereby producing aurorae, would cer- 

 tainly seem to favor the idea that corpuscular radiation of some sort is 

 responsible for this phenomenon. 



One experimental way by which we might determine the relative 

 importance of ultraviolet light and corpuscular radiation from the sun, 

 if such exists, is to observe the radio effects during the phenomenon of 

 a total eclipse of the sun. Measurements of the Heaviside layer 

 heights during the eclipse of 1932 revealed a marked change in the 

 ionization coincident with the arrival of the moon's shadow. As the 

 moon passed off the sun and the normal daylight was restored, the 

 apparent height of the ionized layer again resumed its normal value 

 through the day. 



114728—39 12 



