NO. 



AREQUIPA PYRHELIOMETRY ABBOT 



21 



The data of figure I have been represented by the following two 

 formulae, one expressing the radiation e li2 (reduced to mean solar 

 distance) as a function of vapor pressure, p, alone, the other as a 

 function of vapor pressure, p, and transmission a 2 : 



Formula I. e c 



= 0.981+ °-75 



AO-222 



Formula II. e™ r 2 r =i.$o + (5-25-^)0.19+ (^-0.85)0.63 



<A 



i*^ 



^ 



vr 



-fer- 



2\ 



J 



Areq. 



Monthly 



Mean 



Value,; 



RADIATION. |5EC.Z=| 2.2. 

 WATEfji-VAPOH PRES: UR£. 



ATMO 5PHER IC TRAllSMlSS] 3W 



Jan. Feb Mar Apr Mat June July Aug Sept. Oct No* Dec. Jan 



Fig. 2. 



We now come to a very interesting application of these formulae. 

 During the period of about four years covered by the Arequipa 

 observations, we may assign as the mean value of the solar con- 

 stant of radiation outside the atmosphere 1.93 calories per sq. cm. 

 per min. Dividing by this value we have the following empirical 

 formulae for obtaining from Arequipa daily observations values of 

 the solar constant of radiation : 



Formula I. e n = 



,corr 

 1.2 



o , °-3 8 9 

 °-5o8+ j^i 



Formula II. e n = 



corr 



'1.2 



0.777+ (5.25-^)0.01 + (a 2 - 0.85) 0.33 



