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What is a ‘bomb cyclone’?

GS Paper 1

Syllabus: Important Geophysical Phenomena such as cyclones etc.

 

Source: IE

 Direction: The article tries to explain the concept of air masses and fronts and how they impact the weather of a region.

 Context: An intense blizzard/snowstorm/bomb cyclone is wreaking havoc across the United States and Canada.

 Background:

  • The air flows from high to low pressure, creating winds. Storms form when a mass of low-pressure air meets a high-pressure mass.
  • Forecasters have dubbed the blizzard a “bomb cyclone,” describing it as distinct from typical weather patterns.
  • While this type of storm is not uncommon, it is extremely powerful (as a result of a blast of Arctic air plunging south), with high winds delivering heavy snow or rain to many regions.

 What defines a bomb cyclone?

  • Bomb cyclones form when the air near Earth’s surface rises quickly in the atmosphere, triggering a sudden drop in barometric pressure — at least 24 millibars within 24 hours
  • This quickly increases the pressure difference or gradient, between the two air masses, therefore making the winds stronger.
  • This process of rapid intensification has an even more ferocious-sounding name: bombogenesis.

Concept
 Air masses and fronts Types of air masses How do they influence the weather?
On the basis of temperaturesOn the basis of moisture
●        Air masses are enormous bodies of air that have almost consistent physical properties such as temperature and moisture.

●        Because of the varying densities of nearby air masses, they do not combine easily.

●        As a result, distinctive weather phenomena known as fronts occur at the convergence zone or boundary zone of two air masses.

●        Cold air mass: When the air mass above is cooler than the surface it is relatively unstable since the land is warmer and the air rises after heating, leading to the formation of Cyclones.

●        Warm air mass: It occurs when the air mass is warmer than the surface above it, contributing to atmospheric stability and anti-cyclonic conditions.

●        Continental air masses

●        Oceanic air masses: These are moist, resulting in rainfall. The migration of oceanic air masses toward the Indian subcontinent causes monsoon rains in India.

 

●        Interaction between two different air masses frequently generates atmospheric instability, leading to cyclonic formations.

●        According to the polar front hypothesis, the polar front is created at the meeting point of warm humid air masses from the tropics and dry cold air masses from the poles → low pressure is formed near the polar front resulting in the formation of an extratropical or temperate cyclone.

Insta Links:

Air Masses

 

Mains Links:

Q. Discuss the concept of air mass and explain its role in macro-climatic changes. (UPSC 2016)

 

Prelims Links: (UPSC 2015)

Consider the following statements:

  1. The winds which blow between 30 N and 60 S latitudes throughout the year are known as westerlies.
  2. The moist air masses that cause winter rains in the North Western region of India are part of westerlies.

Which of the statements given above is/are correct?

      1. 1 only
      2. 2 only
      3. Both 1 and 2
      4. Neither 1 nor 2

Ans: 2