1884.] H. F. Blanford— The Winter Bains of Northern India. 57 



have an ascending movement, and this can take place only over a region 

 of low barometer, towards which, therefore, the winds are pouring in. 

 Hitherto no one has attempted the reconciliation of these apparently 

 discrepant conditions. 



Since the establishment of a Meteorological department under the 

 Government of India has rendered it possible to study the weather of 

 India as a whole from day to day, it has been my practice to investigate 

 every case of cold weather rainfall in Northern India, amounting gene- 

 rally to three or four in each year, and although many important points 

 still remain for elucidation, it is now at least possible to clear up many 

 of the difficulties of the problem, and to reconcile the apparent incon- 

 sistencies. 



The charts which accompany the paper show the distribution of at- 

 mospheric pressure and the prevalent winds in the four months of the 

 cold weather. They exhibit many features in common. The region of 

 highest barometer is in the Punjab and the Indus valley, and from this 

 an axis or ridge of high pressure extends across Rajputana and Central 

 India, having a trough of slightly lower pressure in the Gangetic plain 

 and the Northern Punjab on the one hand, and a much lower pressure in 

 the peninsula on the other. The winter monsoon blows around this re- 

 gion of high pressure in an anticyclonic curve, i. e., in the direction of the 

 watch-hands, but in the Punjab and the Gangetic plain there is but little 

 movement of the air, the average rate being less than 2 miles an hour, and 

 calms constitute about one-third of the observations. Also it is shown 

 by the barometric registers of the Himalayan hill stations, that that dis- 

 tribution of pressure which, on the plains, causes the N. B. monsoon, 

 does not exist and is even slightly reversed at an elevation of 7000 feet. 



Hence in Northern India, the state of things which produces the 

 winter monsoon is restricted to a small height, and is then only an aver- 

 age and not a permanent condition ; and that which chiefly characterizes 

 the atmosphere is its stillness ; a condition in which any local action, 

 small and feeble as it may be at first, may eventually set up a distur- 

 bance such as to revolutionize the existing conditions. 



The cold weather rainfall is always the result of a local fall of the 

 barometer, the formation of a barometric depression, which generally 

 appears first in the Punjab or Western Rajputana, and then moves 

 eastwards. Towards and around this depression the winds blow cyclo- 

 nically (t. e., against the direction of the clock-hands) and the winds from 

 the South, coming up charged with vapour which they have collected 

 from the warmer land surface of the peninsula and sometimes from the 

 sea, discharge this as rain chiefly to the Bast and North of the barome- 

 tric minimum where they form an ascending current. 



