What is a Heat Dome?

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Recently, several parts of Europe witnessed an unprecedented winter heat wave and experts said that temperatures increased 10 to 20 degrees Celsius above normal.

Why in news?

  • At least seven countries in Europe recorded their hottest January weather ever. These included Poland, Denmark, the Czech Republic, the Netherlands, Belarus, Lithuania and Latvia.
  • Experts said that the continent is experiencing an extremely warm spell because of the formation of a heat dome over the region.


What is a heat dome?

  • A heat dome occurs when an area of high-pressure traps warm air over a region, for an extended period. The longer that air remains trapped, the more the sun works to heat the air, producing warmer conditions with every passing day. 
  • Heat domes generally stay for a few days but sometimes they can extend up to weeks, which might cause deadly heat waves.
  • Moreover, when air sinks, it gets drier and further raises the temperature of the area.


How is a heat dome formed?

  • The heat dome’s formation is related to the behaviour of the jet stream; an area of fast-moving air high in the atmosphere. 
  • The jet stream is believed to have a wave-like pattern that keeps moving from north to south and then north again. When these waves get bigger, they move slowly and sometimes can become stationary. This is when a heat dome forms.


Previous instances of heat domes

  • In 2021, a heat dome formed over western Canada and the US, causing deadly heat waves. Portland city in Oregon, US, saw the mercury rise to 46 degrees Celsius while the temperature in Washington hit 49 degrees Celsius.


Q1) In what way does pressure affect the Monsoon? 

The pressure difference between the low-pressure region in North India and the high-pressure region near Madagascar creates monsoon winds. The winds pick up moisture from the Indian Ocean and cause rainfall in the Indian subcontinent.

Source: What is causing the winter heat wave in Europe?