74 



H. F. Blanford — On the relations of cloud 



[No. 2, 



the cooling effects of cloud and rain, (the latter especially,) are cumulative, 

 exhibits their influence in a far more striking manner. As the result of 

 the differences of the five months, the ground temperature of May 1880 

 was not less than 4r7° below that of the corresponding month of 1879. 



That the effect of the cloud and rainfall on the temperature of the 

 air was so much smaller than on that of the ground, is doubtless owing to 

 the fact that, after January, the winds of Calcutta are chiefly from the sea. 

 This too perhaps explains the -very striking fact, that on the average of 

 two complete years' observations, the temperature of the ground, at a 

 depth of 3 feet, is not less than 5° higher than that of the air: 



Such being the effect of cloud and rain, at a station situated only 60 

 miles from the sea, and but 20 miles from the broad estuary of the Hoogh- 

 ly, up which much of the sea wind blows to Calcutta, it may be expected 

 that, in the continental climate of Upper India, this influence will be far 

 more pronounced. That such is, in fact, the case, is strikingly shown by a 

 comparison of the temperature, cloud and rainfall of the North- West Pro- 

 vinces in the dry and rainy seasons of 1877 and 1879 respectively. In the 

 former year, the months of March, April and May were unusually cloudy, 

 and the rainfall, although not excessive, was, on the whole, above the 

 average. In 1879, these months were unusually dry and serene. On the 

 other hand, the conditions of the rainy months, June ; July, and August 

 of the two years, were relatively reversed ; the rainfall of 1877 being very 

 deficient, while that of 1879 was more copious than usual. The result of 

 these variations on the temperature is well shown in the following table, 

 which gives the mean temperature anomaly, the mean cloud proportion, 

 monthly rainfall and number of rainy days deduced from the abstract 

 registers of the five stations, Meerut, Agra, Lucknow, Allahabad, and 

 Benares : — 





Temperature 



Cloud pro- 



Rainfall : 



Raint: 



DAYS. 





anomaly. 



portion. 



INCHES. 





1877. 



1879. 



1877. 



1879. 



1877. 



1879. 



1877. 



1879. 



March, 



—1-4 



+ 0-9 



3-85 



247 



0-58 



0-18 



2-0 



1-4 



April, 



—4-0 



+ 37 



3-22 



103 



052 



0-07 



1-6 



04 



May, 



—1-3 



+ 4-7 



2 63 



1-38 



43 



002 



1-6 



06 



Mean, ... 



—2-2 



+ 31 



323 



1-63 



051 



0'09 



17 



08 



Difference, 





+ 53 





—160 



... 



—042 





— 0'9 



June, ... 



+ 1-8 



—0-8 



326 



4-66 



1-40 



478 



3-0 



9-2 



July 



+ 4-3 



—20 



5-48 



7-91 



3-00 



11-61 ' 



60 



16 2 



August, ... 



+ 6-8 



—20 



441 



8-07 



3'21 



11-14 



4-8 



226 



Mean, 



+ 4-3 



—16 



4-38 



6-88 



254 



9-18| 



4-6 



160 



Difference, 





—5-9 





1-2-50 





4 6-64 | 





11-4 



, 



