TABLE 9. THE MEAN OBSERVED MAGNITUDES OF THE INTENSITY OF SOLAR 

 RADIATION AT THE MEAN DISTANCE BETWEEN THE EARTH AND 

 THE SUN (G-CAL/CMS/MIN) 



Table 9, based on data by Kalitin, shows the observed mean values of intensity of solar ra- 

 diation for several locations in the arctic. For comparison, it needs to be pointed out that the 

 maximum intensity of solar radiation observed on the globe (in the Sahara) equals 1.58 g-cal/ 

 cm^/min. 



Table 9 demonstrates conspicuously the magnitude of the intensity of solar radiation in the 

 arctic during summer. At the same altitude of the sun, it is, for instance, considerably higher on 

 Franz Joseph Land (in Bukhta Tikhaya) than in Slutsk and Tashrent. 



On the average, however, the radiation in the arctic is, understandably, considerably less 

 intense than at more southern latitudes. Thus, if the yearly amoimt of solar radiation on Franz 

 Joseph Land, reduced to perpendicular surface, equals about 46, 000 cal/cm2, on Moscow it will 

 be about 104, 000 cal/cm2, on Tashrent about 177, 000 cal/cm2. 



The solar energy, passii^ through the atmosphere, is partly absorbed, partly diffused. Part 

 of the absorbed energy reaches the earth's surface in the form of long-wave radiation, without 

 cessation during the night. 



The diffused radiation is the consequence of the scattering of solar energy by air molecules 

 and water vapor and by extraneous ingredients, such as dust particles and water droplets sus- 

 pended in the air . 



It is understandable that during complete cloudiness and during the twilight only the diffuse 

 solar radiation is available. Hence, it follows that in the arctic, where the sun's elevation is 

 limited and where clouds and fog prevail, the diffuse radiation is of especial significance. 



Table 10, which is based on data by Kalitin, lists the maximum diurnal sums of intensity of 

 diffuse solar radiation for various points in the arctic . 



In arctic areas, the diffuse radiation is considerably more intense than in more southern 

 latitudes. Thus, in Slutsk, where the diffuse radiation had been continually recorded for 9 years, 

 the intensity of diffuse radiation did not exceed 0.59 cal/cm^ min, while in the arctic, the indi- 

 vidual measurements reached 1 cal/cm^ mtn. Hence, the diurnal sums of diffuse radiation in the 

 arctic exceeded by almost twice the sum for the more southern latitude. 



28 



