A heat dome is caused by a persistent region of high pressure. The heat dome can stretch over several states and leave the people, crops and animals below to suffer through stagnant, hot air that feels like an oven.
The jet stream is a band of fast winds high in the atmosphere that usually runs west to east.
Normally, the jet stream meanders north and then south and then north again. The meanders can become stationary when they become bigger. There can be heat domes at that time.
Air piles up and sinks when the jet stream goes to the north. The air warms as it sinks and the skies are clear. The sun creates hotter and hotter conditions around the ground.
The air can warm even more if it passes over mountains. During a heat dome event in the Pacific Northwest in 2021, Washington set a state record with 120 degrees Fahrenheit, and British Columbia set a Canadian record with 121 degrees F.
The heat domes can last a long time in one location. They can change their surroundings over a week or two. Over the course of time, the heat dome crept eastward.
Sometimes the heat dome can be more persistent. In 1980 there were as many as 10,000 deaths in the southern Plains due to high summer heat. During the Dust Bowl years of the 1930s, it happened over a large part of the United States.
Weak winds and an increase in humidity can be caused by a heat dome because of the stagnant weather pattern. The human body is not cooled as much by sweating.
The heat index is a combination of heat and humidity that can be used to show the danger. The amount of cooling is reduced by the high humidity. The risk of heat illnesses and deaths can be increased by the lack of air conditioning during warm nights. Global warming has already increased temperatures.
In the summer of 1995 an estimated 739 people died in the Chicago area due to a heat dome.
The heat wave in the west has been updated.
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William Gallus was the author.
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