What is a heat dome; why won’t it leave?

A heat dome is a huge expanse of hot air caused by a stagnant high-pressure system. Heat domes occur every year when high pressure builds in summer as the land heats more quickly than the ocean. Most move along within a few days, but sometimes a combination of factors keeps the hot air in place for a long time.

What is a heat dome; why won’t it leave?
Source: NOAA. The Washington Post. Published on July 21, 2011, 9:06 p.m.
 
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