192 



ANNUAL KEPORT SMITHSONIAN INSTITUTION, 193 5 



LOV^ 



tion of the ultraviolet light by the ozone is determined. To obtain 

 the results used to construct figures 5 and 6 a number of spectro- 

 graphs were made and distributed over Europe, and spectra were 

 taken of sunlight on every day that the sun was visible. Naturally, 

 on many of the days when, from the meteorological conditions, we 

 should most have liked to have measurements, the sun was com- 

 pletely hidden by clouds and observations were impossible. More 

 recently another instrument has been made by which the amount 

 of ozone can be obtained on almost any day with great ease. Un- 

 fortunately these new instruments are expensive and it has not yet 

 been possible to make a number of them and to have measurements 



made regularly at a num- 

 ber of places in Europe 

 in order to study in de- 

 tail the connection be- 

 tween the amount of 

 ozone and the weather 

 conditions. Such a study 

 might reveal the real na- 

 ture of this connection 

 and be of great value in 

 weather forecasting. 



Already we know that 

 the amount of ozone is 

 very closely associated 

 with many meteorologi- 

 cal conditions in the up- 

 per air. When the trop- 

 osphere is warm, the 

 ozone content is usually 

 high and vice versa. It 

 is also closely connected with the pressure of the air at great heights, 

 the amount of ozone being small when the pressure is high. The 

 closest connection yet found is between the amount of ozone and the 

 density of the air at a height of about 18 kilometers, or, what is 

 nearly the same thing, the amount of heat the air has absorbed. 

 The reason for these connections is not known at present, but they 

 may clearly have an important bearing on meteorology when they 

 are thoroughly understood. At present further progress is largely 

 dependent on money with which to make the necessary instruments. 



ELECTRICAL CHARACTERISTICS OF THE UPPER ATMOSPHERE 



Results from terrestrial inagnetism. — The first suggestion that the 

 upper atmosphere was a good conductor of electricity resulted from 

 a study of the magnetic field of the earth. Accurate pieasurements 



— — — Ozone 

 Pressure 



Figure 6. — Ozone in anticyclonic areas. The con- 

 tinuous and dotted lines are as for figure 5. Note 

 that the ozone values are low over the whole 

 area. 



