Heat dome
Topic: Atmospheric Pressure, Winds and General Circulation · NCERT: Beyond NCERT
Meaning
A heat dome is a strong high-pressure system high up in the atmosphere that stays in place for days or weeks. It traps hot air below it, like a lid on a pot. The air under it sinks and gets hotter as it is squeezed. The sky stays clear, the sun beats down and the soil dries out, so the heat keeps building. Heat domes often form when Rossby waves, which are giant loops in the upper winds, stall in one place. This stalling is called "blocking".
Example
In the Pacific Northwest heat dome of June 2021, Lytton in British Columbia, Canada, reached 49.6 °C. This was a record for Canada.
Don't confuse with
- Heat wave: this is the period of extreme heat that people feel at the surface. A heat dome is one weather pattern that can cause it. In India, heat waves often come with an anticyclone over north-west India.