3G2 MR, S. A. HILL ON THE WINDS OF NORTHERN INDIA, AND THEIR 
in the Nilgiris and Satpuras, such as cause the diurnal mountain winds above referred 
to. The high pressure region in the Deccan is much enlarged, and the centre shifted 
northwards to Berar. Bound this the isobars curve in a nearly triangular form, 
following closely the outline of the country as bounded by the sea, the Hala and 
Suleiman ranges and the Himalayas; the most important exception to this rule being 
a recurvation of the lines of equal pressure round a low-pressure area extending 
obliquely across Bengal from Balasore to Assam. The wind system, induced by this 
distribution of pressure, would be S. or S.W. in the valley of the Indus and Bajputana, 
W. or N.W. over the rest of Northern India, as far east as Low r er Bengal and 
as far south as Berar, S.W. in Eastern Bengal and Burma, N.E. along the eastern side 
of the Peninsula from Orissa to Negapatam, and S.E. or S. on the Malabar coast. 
That is to say, over the interior of Northern and Central India the upper currents in 
this month have exactly the same direction as the anomalous hot winds which we have 
reason to suppose may be caused by their descent under the convective action set up 
by the daily passage of the sun. 
The steepest gradient on the map is that to the west of the Orissa coast. Distur¬ 
bances originating at the head of the Bay would therefore, according to the usual 
experience that the line of least resistance is that of lowest pressure, experience much 
difficulty in proceeding westwards, but would meet with less resistance in the north - 
ward direction over Bengal. As a matter of fact, the majority of such storms as are 
formed in this region during May do proceed northwards," and those which turn 
westwards across the plain of Orissa do not survive to reach the Central Provinces. 
Mr. Eliot attributes their rapid break-up to the comparatively small height to which 
they extend in the atmosphere, and the resistance they experience from the hills west 
of Orissa; but, while this may be one reason for their disappearance, the rapidly 
increasing pressure in a westward direction at moderately great elevations is doubtless 
another. 
The low-pressure area extending obliquely across Bengal and Assam is the scene of 
frequent local storms, known as “ Nor’-Westers,” in the hot season, and the area of 
maximum “ spring storm rainfall ” on Mr. Blanford’s charts! coincides very closely 
with it. At page 105 of the work cited, Mr. Blanford gives a clear and interesting 
description of these storms and their origin, which he attributes to the mixing, by 
convective action, of the southerly sea winds with the north-west winds, which blow 
over the Chutia Nagpur plateau, and probably continue their course eastwards over 
the low plains of Bengal at nearly the same level. The line of maximum rainfall in 
May, according to Mr. Blanford’s Table, passes through or near the following 
places, the rainfall gradually increasing as the distance from the sea increases and the 
Khasia Hills are approached :— 
* “ Account of S.W. Monsoon Storms generated in the Bay of Bengal during the years 1877 to 1881,” 
by J. Eliot, ‘ Indian Meteorological Memoirs,’ vol. 2. 
t “ The Rainfall of India,” ‘ Indian Meteorological Memoirs,’ vol. 3. 
