What is a heat dome? The US heatwave explained

An intense heatwave is set to blanket much of the central and eastern United States this week as a “heat dome” settles over the region, bringing days of oppressively high temperatures and humidity ahead of the Fourth of July weekend and FIFA World Cup matches in several US cities. Forecasters say in some places it could feel as hot as 46 degrees Celsius (115 degrees Fahrenheit). Dozens of temperature records could be broken, according to the National Weather Service (NWS), which called the conditions “dangerous”. More than 60 million people are currently under heat alerts. Recommended Stories list of 4 items end of list At the centre of this week’s forecast is a weather phenomenon known as a heat dome. What is it, and why does it make heatwaves even more intense and unbearable? What is a heat dome? A heat dome is a large area of high pressure, formed when warm air flows northward, that acts like a lid over the atmosphere, trapping hot air close to the ground. As the air sinks, it compresses and warms even more. At the same time, the pressure system helps prevent cooler air and storms from moving in, allowing heat to build at the surface and remain trapped there. With few clouds and little wind, the sun has more direct access to the ground, creating a heat feedback loop. Heat domes are linked to prolonged heatwaves that can last for days. …