What is a Heat Dome and Why Do They Cause Soaring Temperatures?

With 2023 smashing all previous global temperature records, heatwaves are becoming far more frequent than they formerly were. The summer of 2023 was really the warmest on record since temperature records have been kept, which dates back almost 140 years. Why do heat domes raise temperatures so much, and what exactly is a heat dome? We will now discuss this event as well as others that lead to heatwaves.

What is a Heat Dome?

A heat dome is produced when an area of high pressure passes over a region for a few days or weeks. Heat domes produce heat waves when they are positioned over an area.

Heat domes are not always the result of high pressure systems. Air sinks in a high-pressure environment, and rising temperatures result from this phenomenon. The moment that sinking air is trapped and unable to leave, it turns into a heat dome.

Although they can remain longer, heat domes typically last one to two weeks. Over a month was spent in 2023 over the Southwest region of the United States under a heat dome.

Changes in the Pacific jet stream are typically the cause of heat domes in the United States. This jet stream is a significant air movement that travels across North America in a wave-like pattern from west to east.

The Pacific jet stream’s wave-like motion can occasionally intensify into a more dramatic wave, and the air that snakes across North America may slow down. Static air accumulates and sinks in the regions beneath a jet stream that has shifted significantly to the north. This prepares the Southwest for a heat dome.

What is a Heatwave?

A heatwave is a time when the average daily temperature is significantly higher than usual and may also include higher humidity levels. It takes two or more days of high temperatures to qualify as a heatwave. On the other hand, heatwaves can last for months, and they typically peak under a heat dome.

Heatwaves are the most dangerous weather phenomena in the United States, despite the fact that they are often and experienced by most people. Heatwaves have been the leading cause of death in the US for the past 20 years compared to all other extreme weather events.

Why Do Heat Domes Cause Soaring Temperatures?

High pressure confines hot air beneath heat domes, causing temperatures to surge, much like a pot cover. The trapped air becomes hotter while the dome is in place longer because the Sun keeps heating it. Weeks pass, and as each day gets hotter than the last, a heatwave occurs.

Additionally, clouds, rain, and other elements that could cool the land beneath a heat dome are kept at bay by heat domes. For instance, ocean winds were unable to break through a heat dome that covered the Pacific Northwest in 2021.

Are All Soaring Temperatures Caused by Heat Domes?

Heat domes are mostly to blame for the high temperatures that lead to heat waves. In spite of this, additional events intensify the global development of intense heat waves. Heat domes produced by mechanisms specific to that region of the earth are the source of different heatwaves.

El Niño exacerbates heat domes caused by anticyclones and the Pacific jet stream, and anticyclones themselves generate heat waves. Heat waves are also significantly influenced by climate change.

Heat islands can occasionally intensify the oppressive temperatures inside a heat dome. Major cities absorb heat during the hottest part of the day, such as Phoenix, Arizona, or New York City. Then, at night, they emit this heat, maintaining a greater daytime low than would occur normally.

El Niño Exacerbates Hot Conditions

El Niño is the term used to describe the warming of ocean water in the Pacific Ocean around the equator off the west coast of the Americas. This occurs roughly every two to seven years, however it’s difficult to estimate with certainty when the warming will take place. Although it can stay considerably longer, El Niño typically lasts up to a year.

There are trade winds along the equator that blow westward most of the time. Warm water close to South America is dragged toward Asia by this wind. In order to replenish the water that is lost, colder water from the ocean’s depths upwells to the surface when this happens.

This usual trade wind becomes weaker during an El Niño. The weaker winds prevent warm water from moving westward, which results in higher-than-normal ocean temperatures close to the Americas. Because El Niño is warming the ocean, more heat is released into the atmosphere, which leads to greater temperatures in North America.

Anticyclones Create Heat Domes and Cause Soaring Temperatures

High-pressure systems known as anticyclones are what produce the hot weather. Though they also produce catastrophic heat waves, they differ slightly from the heat domes typical in the American Southwest.

Air molecules are compressed as it descends toward the planet’s surface during an anticyclone. Air moving counterclockwise in the Southern Hemisphere and clockwise in the Northern Hemisphere pushes the air toward the ground. Temperatures rise as the pressure of the sinking air rises.

Dry and hot weather conditions are the outcome of anticyclones because their air circulates and creates an inner area of static and sinking air. There are no clouds in the area, and the breezes that do exist are mild. A heat dome forms as the sun bakes the interior’s static charge.

How Climate Change Creates More Heatwaves

Globally, there are more hot days and nights as a result of climate change. Human activity is the primary source of Earth’s lower atmosphere’s progressive warming, which has an impact on the planet’s atmospheric circulation. It also has an impact on the movement of water across the oceans.

The consequences of El Niño episodes are amplified, among other things, by this rise in atmospheric heat. Ocean temperatures rise as a result of changes in wind currents and jet streams. This indicates a rise in the availability of the components needed to make heat domes.

In certain regions of the world, climate change might make heat domes worse. Other forms of extreme weather are also produced by it. For instance, when climate change intensifies, storm surges, tornadoes, and hurricane frequency all increase.