156 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



(2) Whirlwind having an average velocity (see fig. 10.) 



Let the latitude = 60°, 



k = 0.00012 

 v = 15 m , 



r =7° 



- =0.0009404 (r = 0°, b = 750 m "'). 

 P 



We shall find 



19.43 10 5.5 

 a == 40° 23.3'; G -- + ~j- 



r r 



r ">2.75 r n 



b-b = 44.73 log - + 1 . 070 - ; <p = 138 . 5 log . — • 

 r r- T r 



r = 7° 8° 9° 10° 12° 15° 20° 



v = 15 ,n 13. l m 11. 7 m 10. 5 m 8.7 7.0 m 5.2 m 



G = 3.08 lnm 2.64 mm 2.30 mm 2.05""" 1.68 mm 1.33 mm 0.98 mm 



b - b Q = mm 2.8 mm 5.3 mm 7.5 m,n 11.2 mm 15.6 mm 21.3 mm 



- <p = 0° 8° 15° 21° 32° 46° 63° 



§13. Horizontal currents of air with circular isobars around a 



barometric maximum 



By making the same hypothesis as in § 12, Ave shall find the same 

 equations, but it is necessary to write 



4> = 180° + a (1) 



and to change the sign of the gradient, on the supposition that the 

 pressure diminishes with distance from the center. We shall then 

 have 



vr = v r 



P- - kv r 1 v 2 r„ 2 . 



u- = . — « (2) 



p cos a r r 



where 



a a 

 G ~-r-S < 3) 



a r a' I I i \ 



b >- b =M 1C 'Z U + 2\,<- r.>) ' ' W 



