Heat Dome

Mains Marks Booster     5th August 2023        
Samadhaan

Introduction

Several countries in Europe experienced record-breaking temperatures in January, with temperatures 10 to 200C above average. This phenomenon was attributed to the formation of a heat dome over the region. Heat domes have become more frequent and intense in recent years, causing deadly heat waves. 

Heat Dome

  • A heat dome occurs when an area of high-pressure traps warm air over a region for an extended period, similar to a lid on a pot.
  • Trapped air gets heated by the sun over time, resulting in increasingly warm conditions.
  • Heat domes typically last for a few days but can persist for weeks, leading to deadly heat waves.
  • Air sinking under high pressure gets compressed, becoming even warmer, and drier, further raising temperatures.

Heat Domes and the Jet Stream

  • Jet streams are narrow bands of strong wind in the upper atmosphere.
  • The jet stream has a wave-like pattern that oscillates between north and south.
  • When these waves become elongated and stationary, high-pressure systems get stuck, forming a heat dome.
  • Climate change may be intensifying heat domes by increasing the waviness of the jet stream, resulting in more frequent extreme heat events.
Heat Domes

Causes of Formation of Heat Dome

  1. Change in Ocean Temperature
  • A strong change or gradient in ocean temperatures initiates the heat dome formation process.
  • Convection occurs, with warm air rising over the ocean surface due to the temperature gradient.
  • Prevailing winds carry the hot air eastward, while shifts in the jet stream trap and move it toward land, where it sinks, leading to heat waves.
  1. Change in Atmospheric Pressure
  • Heat waves begin when high-pressure systems in the atmosphere push warm air toward the ground.
  • Heat rising from the ocean fuels this effect, creating an amplification loop.
  • The high-pressure system expands vertically, altering the course of other weather systems, reducing wind and cloud cover, and prolonging the heat wave.
  1. Climate Change
  • Rising temperatures caused by global warming contribute to hotter weather conditions.
  • While heat waves have always occurred naturally, climate change has amplified their intensity, duration, and frequency.
  • Scientists studying the climate agree that human-induced climate change plays a significant role in the occurrence of heat waves.
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