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What is the ‘heat dome’ causing record temperatures in parts of North America? 

Topics Covered: Important Geophysical phenomena. 

What is the ‘heat dome’ causing record temperatures in parts of North America? 


Context: 

Parts of Canada and USA are reeling under severe heat wave caused due to a heat dome. 

 

What Is A Heat Dome? 

A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap. 

  • The scorching heat is ensnared in what is called a heat dome. 
  • High-pressure circulation in the atmosphere acts like a dome or cap, trapping heat at the surface and favoring the formation of a heat wave. 

 

Causes: 

  • This happens when strong, high-pressure atmospheric conditions combine with influences from La Niña
  • This creates vast areas of sweltering heat that gets trapped under the high-pressure “dome“. 
  • The main cause is a strong change (or gradient) in ocean temperatures from west to east in the tropical Pacific Ocean. 

 

How is it created? 

  1. In a process known as convection, the gradient causes more warm air, heated by the ocean surface. 
  2. This rises over the western Pacific, and decreases convection over the central and eastern Pacific. 
  3. As prevailing winds move the hot air east, the northern shifts of the jet stream trap the air. 
  4. Thus winds move it toward land, where it sinks, resulting in heat waves. 

 

Impact of a heat dome: 

  1. Lead to a sudden rise in fatalities due to extreme heat like conditions. 
  2. Trapping of heat can also damage crops, dry out vegetation and result in droughts. 
  3. The heat wave will also lead to rise in energy demand, especially electricity, leading to pushing up rates. 
  4. Heat domes can also act as fuel to wildfires, which destroys a lot of land area in the US every year. 
  5. Heat dome also prevents clouds from forming, allowing for more radiation from the sun to hit the ground. 

 

Insta Curious: 

Similar to heat domes, cold-domes are formed in some parts of the world. Know what causes their formation, Click here

 

InstaLinks: 

Prelims Link: 

  1. About La Nina. 
  2. El Nino. 
  3. What is heat dome? 
  4. Causes. 
  5. Impact. 

Mains Link: 

Discuss the impacts of heat domes. 

Sources: Indian Express.