Exploring the Science of Heat Domes

1. What is a Heat Dome?

A heat dome is a high-pressure weather system that traps hot air close to the surface, preventing it from escaping. This leads to prolonged periods of intense heat. As the sun continues to warm the air, the trapped heat accumulates over several days, often resulting in extreme and persistent temperature spikes.

2. Why Do Heat Domes Occur?

• Formed by a stationary or slow-moving ridge of high pressure in the atmosphere.
• The jet stream, which usually moves weather systems, may shift northward or weaken—allowing hot air to remain trapped over one region.
• The dome acts like a lid, preventing cooler air and clouds from entering, causing temperatures to rise sharply.

3. Where Have They Been Recently Observed?

• United States: Record-breaking heatwaves in June across the eastern regions.
• Europe: Severe heat led to the temporary closure of landmarks like the Eiffel Tower.
• China: Prolonged heat spells caused crop losses and serious public health concerns.

4. What Are the Impacts of a Heat Dome?

• Health Hazards: Increased risk of heatstroke, dehydration, and respiratory issues.
• Agriculture: Heat stress on major crops such as corn and soybeans reduces yields.
• Economy: Power grid overloads, lower labour productivity, and disruptions in transportation systems.
• Environment: Heightened risk of droughts and wildfires, particularly in arid areas.

5. Why Are Heat Domes Hard to Forecast?

• They develop rapidly and depend on complex interactions among ocean temperatures, atmospheric pressure, and jet stream behaviour.
• Unlike El Niño, which can be tracked months ahead, heat domes offer minimal advance warning.
• Forecasting their exact location, duration, and intensity remains a major meteorological challenge.

6. Is This Relevant to India?

• Although the term heat dome is not often used in the Indian context, similar conditions occur across the northern plains and central India during April–June.
• Recent years have witnessed patterns resembling heat domes contributing to record-breaking summer temperatures and increased heatwave frequency.