12 



LUNAR EFFECT 



Expressed analytically, the lunar-diurnal variation in the two seasons is as 

 follows : 

 In summer, 



AC = _0'.006 + 0'.02S sin (e + 18) + 0'.2T8 (29 + 61) 

 In winter, 



A< = +0'.005 + 0'.058 sin (s + 264) + 0'.173 (29 + 115) 



The characteristic feature of the annual inequality in the lunar-diurnal variation 

 is, therefore, a much smaller amplitude in winter than in summer. Kreil, indeed, 



Ltrif AB-DIURNAL VARIATION. 



In summer 



In winter 



+0'.30 

 .25 

 .20 



! 'II 



.05 



0.00 



.05 



; .10 



i .15 



.20 



.25 



0.30 





11,1 



O'i. i 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 241'. 

 U. C. L. C. U. C. 



Summer curve from 11,087 observations (.) 

 Winter " " 111/)".? " () 



