60 John Eliot — On the occasional Inversion of tlie Temperature, 8fc. [No. 1, 



of the weather, and will increase slowly with the melting 

 of the snow in the hills. Hence one of the most striking 

 features is the low maximum temperatures recorded at 

 such periods in Upper or Northern India, although the 

 air is unusually clear, and the solar radiation at the earth's 

 surface more intense than usual. 

 Zrd. One of the chief features of a descending current is 

 great dryness, hence the descending currents from the hills 

 at such times will tend to give abnormally low humidity to 

 the whole area over which their influence extends. The 

 change of humidity due to this will evidently be greatest 

 in the area over which damp sea winds previously prevail- 

 ed, that is, usually in Bengal. 

 It will thus be seen that the features of the very cool and dry 

 periods after stormy weather in Northern India during January and 

 February are explicable on the assumption of unusually large and 

 massive currents from the hills at a time when the snow surface has 

 greatly extended downwards. 



It is hardly necessary to point out that these cool periods are of 

 occasional occurrence in Bengal, and are the most characteristic and 

 pleasant feature of the cold weather. These cool periods in Northern 

 India hence shew most strikingly the rapid and large influence which 

 snowfall over a large mountain area exerts. Mr. Blanford and myself 

 have shewn the probably large influence it occasionally exercises on the 

 distribution of the south-west monsoon rainfall. This has been ques- 

 tioned by some writers as the effect appears to them to be dispropor- 

 tionate to the cause. The large changes in air motion, temperature, and 

 humidity over the whole of Northern India which follow general snowfall 

 in the hills, and which continue for longer or shorter periods according 

 to the intensity and extent of the storm, are a frequent strong argument 

 in its favour. 



