HEAT DOME (Syllabus: GS Paper 1 – Geography)

Context: A sweltering heatwave has engulfed the entire western United States, with California being the hardest hit as a dozen cities break all-time high-temperature records. This scorching heat and dry conditions are due to a heat dome centered over California.

Heat Dome

• About: It is a type of high-pressure system that forms over a large area in the atmosphere, and causes extremely hot and dry weather conditions.
• Formation of Clear Skies: As the warm air is not able to rise upward, the sky remains clear since clouds form under the opposite circumstances when rising warm air cools down and condenses.
• Increased Sunlight Exposure: The high-pressure system allows more sunlight to reach the earth, resulting in more warming and drying of the soil.
• Solar Heating Effect: The trapped air undergoes heating from the sun over time, contributing to a gradual increase in temperature.
• Duration of Heat Domes: While heat domes usually endure for a few days, they can persist for weeks, often resulting in hazardous heat waves.
• Atmospheric Compression and Temperature Rise: Under high pressure, descending air undergoes compression, intensifying both its warmth and dryness, consequently elevating temperatures.
• Role of the Jet Stream: A heat dome’s formation is tied to the behaviour of the jet stream, an area of fast-moving air high in the atmosphere that usually helps move weather systems along the Earth’s surface.

Impact of Climate Change on Heat Domes

• Scientists are still debating how climate change impacts blocking weather events that cause heat domes, but rising global temperatures have made heat domes larger and more intense.
• A 2021 study by 27 climate researchers from the World Weather Attribution found that the searing temperatures during the 2021 heat dome in Canada would have been virtually impossible without human-caused climate change.
• A study published in Nature in 2023 indicated that the intensity of heat domes is outpacing the rate of global warming, suggesting that climate change is fuelling their intensity.