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Making local sense of food, urban growth, population and energy

Winds of monsoon India

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RG_India_monsoon_winds_20150613

This panel of four images shows: top left, winds at around sea level; top right, winds at about 1,460 metres altitude (around 4,780 feet); lower left, winds at 3,010 metres (9,880 feet); lower right, winds at 5,570 metres (18,280 feet).

These are the wind patterns that are bringing the monsoon to us from just above the equator, as they travel east-north-eastwards towards the Indian peninsula, and earlier north-north-westwards as they travelled from near Madagascar and the Mascarene Islands, which lie about 21 degrees south of the equator.

RG_India_monsoon_winds_20150613_bIn the top two images, the south-west (from our point of view) winds sweeping across the Arabian Sea are the dominant feature, with the winds at the higher of the two altitudes (right, at 850 millibars, or mb, which is around 1,460 metres) rushing in at just the direction and velocity they ought to. Winds at near-sea level are less powerful, and in both the two top images winds are also seen travelling due north up the Bay of Bengal.

In the lower two images, the vortex of Cyclone Ashobaa is clearly seen, with wind trails running due east across the Arabian Sea, then across peninsular India and out over the Bay of Bengal towards Burma. More markdly with the winds in the lower left image, which are at 700 mb or 3,010 metres, they scarcely touch central and north-western India and the Gangetic belt (whereas the winds at lower altitudes, as seen in the upper two images, do).

Finally, in the lower right image are the winds at 500 mb, or 5,570 metres. Here we see them streaming powerfully down from the Hindu Kush-western Himalaya, across north India and thence right across the Gangetic belt, through Assam and the north-east. These are the major wind patterns we have now in mid-July, and they will change in strength, direction and intent as El Nino changes and also as the Northern hemisphere summer continues over the Eurasian land mass.

These wonderful images are taken from the ‘earth’ weather observation visualisation which skillfully employs the forecasting by supercomputers of current weather data from the Global Forecast System (GFS) and the NOAA/NCEP climate and weather modelling programmes.

Written by makanaka

June 13, 2015 at 21:54

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