738 



WINDS OF THE GLOBE. 



it beino- N. N. W. in winter, and W. S. W. in summer. Yet Bombay is known to 

 have very marked monsaon seasons, that is, scarcely any rain falls in winter, while it 

 is profuse from June to September. At Madras the monsoons are from the same 

 direction as on the seas in the same latitude, N. E. in winter, S. W. in summer. 

 The relative position of land and sea has in this case a very small influence, other- 

 wise we should have E. and S. E. winds in summer, W. and N. W. in winter. 

 Madras is nearly due South of the lowest pressure in summer, and the difference 

 is sufficiently great to give the prevalence and regularity of S. W, winds. 



The winds at Dodabetta, a high station on the Neilgherries, S. W. of Madras, are 

 peculiar ; N. W. winds prevail in summer and S. E. in winter. This shows that the 

 movement of air which is experienced near the sea-level does not extend very high. 

 The mean direction in winter and summer is more than 90° different from that of 

 Madras and other stations of India in low latitudes, and nearly the opposite of 

 that of Calcutta, Central India and tlie Punjab, as shown by tlie following table: — 





Spring. I 



Summer. 



Autumn 



Winter. 1 





g 



^i 



g 



^1 



1 



o ~ 



1 



*j 









"*3 



a S 





CJ % 



o'i 



p s 



©"a 







S'^ 



P 



B^ 



K " 



s^ 



M " 



^'-o 



« '" 





R. 



30O W. 



.42 



S. 580 W. .88 



S. 630 W. 



.43 



N. 370 W. 



.59 





S. 



2 E. 



.74 



S. 54 W.i.85 



N. 51 W.i.24 



N. 47 E. 



.68 





N 



79 E. 



.i;9 



N. 47 W. 



.81 



N. 42 E. 



.32 



S. 8(i E. 



.C2 



Calcutta 



S. 



1 E. 



.5-5 



S. 13 E. 



.49,t 



N. 4 E. 



.12', 



N. 21 W. 



.31', 



Bareilly 



N. 



51 W. 



.33 



S. U4 E. 



.35 



N. 11 W. 



.12 



N. 52 W. 



.41 



S. 



87 W. 



.11 



S. 42 E. 



.29 



S. 9 W. 



.Utf , 



N. G7 W. 



.18 



Sialkole, near Lahore .... 



IN. 



8(3 W. 



.22 



S. 51 E. 



.49 



S. 80 W. 



.47 



N. 85 W. 



.34 



Bombay 



N 



58 W. 



.02 



8. 70 W. 



— 



N. 25 W. 



.37 



N. 5 W. 



.04 



Thus, on a great part of the continent of India, the motion of air is towards the 

 centre of lowest pressure in the Punjab, as also seen on Plates 5, 6, and 7, while at 

 Dodabetta, 8G40 feet high, it is from the Punjab. It seems thus, that the rarefaction 

 of air does not extend to very high regions. In the winter, on the contrary, air 

 moves from N. W. India towards the Bay of Bengal, and in the opposite direction 

 at Dodabetta. 



Blanford considers the winds at this high station as somewhat similar to the 

 return-trade or westerly winds blowing over the trades on tropical seas. 



At Roorkee the mean pressure in January is 29.15, in June 28.62, difference 

 0.53 inche, at Dodabetta it is 22.18 in January, 22.09 in June, difference 0.09 in. 



It is also seen that the summer monsoon is shorter in the northern part of India, 

 spring and autumn having the same direction of the wind as winter, only the ratio 

 of resultant is smaller. At Calcutta and Madras the S. winds are already estab- 

 lished early in spring, while at Colombo, Ceylon, still farther south, spring, summer, 

 and autumn have the same direction of wind. (See Plate 7.) 



The dominating winds seem also to be the strongest. So, for example, at Bom- 

 bay, the greatest mean velocities were distributed as follows: in May S. S. E. 16.5 

 miles an hour, June S. S. E. 27.5 miles, July W. S. W. 21.4, August S. W. 17.0, 

 December N. N. W. 13.9, January N. N. W. 14.1, and in February N. W. 14.6. 



