What is a heat dome? What to know as dangerous heat wave expands east
A dangerous heat dome has enveloped the Midwest, South and East Coast, bringing prolonged extreme heat to more than 30 states this week.
So what is a heat dome?
A heat dome occurs when the jet stream -- the steering winds high in the atmosphere -- pushes north, allowing hot and humid air to move north along with it.
The jet stream rides along the edge of a strong area of high pressure; this area of high pressure is the real "heat dome."
Under high pressure, air sinks and condenses, creating a layer of air that traps the heat and allows it to bake to extreme temperatures.
Heat domes in the U.S. generally span a third or half of the country. These extreme conditions often last for days but can be longer than a week.
Heat waves are becoming more frequent, more intense and longer lasting due to human-amplified climate change, according to the federal government's Fifth National Climate Assessment. The average number of heat waves in major U.S. cities each year has doubled since the 1980s, that report noted.
Extreme heat is the deadliest weather-related hazard in the U.S.
Click here for tips on how to stay safe.
