Heat dome

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A heat dome, over the United States

A heat dome is caused when atmosphere traps hot ocean air, as if bounded by a lid or cap. Heat domes happen when strong high pressure atmospheric conditions remain stationary for an unusual amount of time, preventing convection and precipitation and keeping hot air "trapped" within a region. This can be caused by multiple factors, including sea surface temperature anomalies and the influence of a La Niña.[1][2] The upper air weather patterns are slow to move, referred to by meteorologists as an Omega block.[3]

Creation of heat domes[edit]

In still, dry summer conditions, a mass of warm air builds up. The high pressure from the Earth's atmosphere pushes the warm air down. The air is compressed, and as its net heat is now in a smaller volume, so it must get hotter. As the warm air attempts to rise, the high pressure above it forces it down, to get hotter, and its pressure grows higher.[4]

The high pressure acts as a dome, causing everything below it to get hotter and hotter.[5] The term is often extrapolated in the media terminology for any heat wave situation. The term heat dome is also used in the context of urban heat islands.[6]


The heat dome of the 2021 Western North America heat wave, over west Canada and the Northwest United States. The "high" pressure at left is the heat dome

In chronological order,

See also[edit]


  1. ^ "What is a heat dome?". National Oceanic and Atmospheric Administration. June 30, 2021.
  2. ^ Burga, Sulcyre (27 July 2023). "What to Know About Heat Domes—And How Long They Last". Time.
  3. ^ Freedman, Andrew (July 25, 2019). "A Giant 'Heat Dome' Over Europe Is Smashing Temperature Records, And It's on The Move".
  4. ^ Rosenthal, Zachary (July 1, 2021). "Extreme heat". AccuWeather.
  5. ^ Fleming, Sean (June 29, 2021). "What is the North American heat dome and how dangerous is it?".
  6. ^ Lacroux, Margaux. "Qu'est-ce que le «dôme de chaleur» qui fait suffoquer le Canada ?". Libération (in French). Retrieved 2022-11-08.

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