scholarship 2024

Current affair diary 15/1/2021

Subject: Geography

Polar Vortex

√Polar Vortex Threatens To Send US, Europe Into Deep Freeze

√Meteorologists have predicted that the polar vortex, which is splitting into two and swirling southward, will send the US and European countries into a chilling deep freeze.

√It is described as a whirling cone of low pressure over the poles that is strongest in the months due to the increased temperature contrast between the polar regions and the mid-latitudes, such as the US and Europe.

√The polar vortex spins in the stratosphere.

√Usually, when the vortex is strongest, cold air is less-likely to plunge deep into North America or Europe.

√ it forms a wall that protects the mid-latitudes from cold Arctic air.

√But occasionally, the polar vortex is disrupted and weakens, due to wave energy propagating upward from the lower atmosphere. When this happens, the stratosphere warms sharply in an event known as sudden stratospheric warming, in just a few days, miles above the Earth’s surface.

√ The warming weakens the polar vortex, shifting its location somewhat south of the pole or, in some instances, ‘splitting’ the vortex up into ‘sister vortices’.

√ The split higher up in the atmosphere can give rise to both, sudden and delayed effects, much of which involves declining temperatures and extreme winter weather in the eastern US along with northern and western Europe.

√ A sudden stratospheric warming also leads to a warm Arctic not only in the stratosphere but also in the troposphere as well.

√ A warmer Arctic, in turn, favours more severe winter weather in the Northern Hemisphere mid-latitudes including the eastern US.

?focus area for prelims 2021:

√ Polar Vortex
√ characteristics
√ sister vortices


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