‘Westerly Jet Stream’ is a fast-flowing, narrow corridor of very strong winds, with speeds in excess of 200km/h and sometimes surpassing 300 km/h. Westerly jets appear in the winter season over the northern half of the Indian region with its core streaming invariably between 25°N and 30°N. These latitudes are not sacrosanct and the roaring belt is subject to gains and drops in the latitudes. These howling winds are the atmospheric streams of speedy winds, prevalent in the higher parts of the atmosphere, frequently seen between 30.000’ and 40,000 feet above the ground level. These winds have a terrific effect on aviation. Advantage, of course, is very limited.
The westerly Jet Stream starts appearing over the Western Himalayas, early in the winter season. The stream keeps strengthening and also lowering in latitude as the season progresses. The narrow core of speedy winds gets down to their southernmost position in February and starts rising in latitude during the spring season and later. These winds are nearly horizontal, running from west to east. However, there are undulations, at times these are embedded with very strong vertical and horizontal wind shear, which result in turbulent and bumpy rides, when the aeroplane flies, across and into these strong headwinds. Many times, that particular flight level may have to be vacated for the sake of convenience.
The only advantage of such strong streams is realized when the flight route is from west to east over northern parts of the country, like Delhi to Guwahati. The aeroplane will get the tail winds and therefore reach the destination faster than the scheduled duration. Therefore, it will save fuel, as well, reducing the cost and carbon prints.
Currently, such strong westerly jet has been a regular feature over the northern parts of the country. Persistently, Westerly Jet Stream with speeds in excess of 250km/h is prevailing over the northern parts. These strong winds are manifested as transverse high cloud bands in the satellite images. Also, due to the undulations in the flow, some cracks develop in the stream. These openings become a source of cold blasts descending down in the atmosphere and causing extreme cold conditions. ‘Polar Vortex’ and the ‘Cold Blast’ invariably are the offshoot of this phenomenon. However, such extreme cases are limited to the mid and high-latitude regions and rarely appear over the Indian region.
Image Credit: dailypioneer
