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Another bomb cyclone over the North Atlantic:

GS Paper 1:

Topics Covered: Important Geographical phenomenon.

 

Context:

Another violent bomb cyclone is grazing north just west of Ireland and UK with violent, hurricane winds and major waves.

  • Thanks to still a very powerful southern lobe of the Polar Vortex aloft, the North Atlantic is yet to produce more dangerous storms this week.

 

What is a Bomb Cyclone?

“Bombogenesis is the technical term. ‘Bomb cyclone’ is a shortened version of it.”

  • It is a mid-latitude cyclone that intensifies rapidly.
  • It has low pressure at its center, weather fronts and an array of associated weather, from blizzards to severe thunderstorms to heavy precipitation.

Generally, a bomb cyclone happens when atmospheric pressure in the middle of the storm drops at least 24 millibars over 24 hours, quickly increasing in intensity. The lower the pressure, the stronger the storm.

 

Why is it called a bomb?

Most cyclones don’t intensify rapidly in this way. Bomb cyclones put forecasters on high alert, because they can produce significant harmful impacts.

Things you should know about a bomb cyclone:

  • Occurs over midlatitudes.
  • Have cold air and fronts.
  • Form during winter.

 

What exactly is a polar vortex?

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

 

Features:

  • The polar vortex spins in the stratosphere.
  • Usually, it forms a wall that protects the mid-latitudes from cold Arctic air.
  • When the vortex weakens, 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’.

 

Insta Curious:

Did you know that all bomb cyclones are not hurricanes? Know the differences between these two here.

 

InstaLinks:

Prelims Link:

  1. What is a cyclone?
  2. Differences between cyclones, hurricanes and typhoons.
  3. What is a Bomb Cyclone?
  4. What is Polar Vortex?
  5. Where is it formed?
  6. Movement of winds in Polar Vortex.

Mains Link:

What is a Bomb Cyclone? How is it formed?

Sources: the Hindu.