The Southwest is baking under a relentless heat wave that has shattered records, triggered excessive heat warnings, and endangered millions of people.
The scorching conditions are caused by a massive zone of high pressure, commonly known as a heat dome, that has parked over the region and trapped hot air underneath.
The heat dome is expected to persist and expand into next week, bringing triple-digit temperatures to parts of California, Nevada, Arizona, Texas, and Florida.
What is a heat dome and how does it form?
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A heat dome is a meteorological phenomenon that occurs when a large area of high pressure builds up in the upper atmosphere, usually at least 10,000 feet above the surface, as per NBC.
High pressure means that air is sinking from above, which compresses and warms the air below.
The high pressure also acts like a lid, preventing the hot air from escaping or mixing with cooler air. As a result, the air underneath the heat dome becomes stagnant and heats up even more.
Heat domes can form in any season, but they are more common and intense in summer when the sun's rays are stronger and heat the ground more.
These can also be influenced by other factors, such as drought, which reduces soil moisture and evaporation that can cool the air; or urbanization, which creates heat islands that trap and radiate more heat than natural landscapes.
Generally, heat domes can last for days to weeks, depending on how strong and stable the high-pressure system is. They can also move or shift over time, affecting different regions.
For example, the current heat dome over the Southwest originated over the Four Corners region of Arizona, Colorado, New Mexico, and Utah, where it typically forms in summer due to intense heating over deserts. It then expanded westward and northward, reaching parts of California and Nevada.
What are the impacts and risks of a heat dome?
A heat dome can have severe impacts and risks for human health, environment, and society. Some of these include:
Heat-related illnesses and deaths
Extreme heat can cause dehydration, heat exhaustion, heat stroke, or even death, especially for vulnerable groups such as children, elderly, outdoor workers, or people with chronic conditions.
According to the Centers for Disease Control and Prevention (CDC), more than 600 people die from heat-related causes in the U.S. each year.
The current heat wave has already claimed at least one life in Arizona, as per The Washington Post.
Increased demand for electricity and water
Extreme heat can increase the demand for air conditioning and refrigeration, which can strain the power grid and cause blackouts or brownouts.
It can also increase the demand for water for drinking, irrigation, or cooling, which can deplete water resources and worsen drought conditions.
Increased risk of wildfires
Extreme heat can dry out vegetation and create tinderbox conditions that can ignite or spread wildfires.
Wildfires can also create smoke and haze that can reduce air quality and visibility. The current heat wave has already sparked several wildfires across the Southwest, including the Telegraph Fire in Arizona, which has burned more than 180,000 acres and forced evacuations.
Damage to infrastructure and crops. Extreme heat can cause thermal expansion and contraction of materials such as asphalt, concrete, metal, or plastic, which can crack or warp roads, bridges, pipes, or cables. It can also damage crops or livestock that are sensitive to high temperatures or water stress.
A heat dome is a natural phenomenon that cannot be prevented or controlled by humans. However, we can take some measures to cope with its effects and reduce its risks. Some of these include:
Staying informed and prepared
We can check the weather forecasts and alerts from local authorities or media outlets to know when and where extreme heat is expected. We can also prepare emergency kits with water, food, medicine, flashlights, batteries, or other essentials in case of power outages or evacuations.
Staying cool and hydrated
We can avoid outdoor activities during the hottest part of the day (usually between 10 a.m. and 4 p.m.), seek shade or air-conditioned places when possible, wear light-colored and loose-fitting clothing, drink plenty of fluids, and avoid alcohol or caffeine that can dehydrate us. We can also use fans, sprinklers, or wet towels to cool ourselves down.
Staying safe and healthy
We can monitor our own health and watch out for signs of heat-related illnesses, such as headache, dizziness, nausea, vomiting, or confusion. We can also check on our family members, friends, neighbors, or pets who may need help or assistance. We can also avoid using appliances that generate heat, such as ovens, stoves, or dryers, and unplug unnecessary devices to conserve energy and prevent overloading the power grid.
Staying aware and responsible
We can follow the guidelines and regulations from local authorities or utility companies regarding water and power conservation, fire prevention, or emergency response.
We can also avoid activities that can spark or spread fires, such as burning trash, using fireworks, or parking on dry grass. We can also reduce our greenhouse gas emissions that contribute to global warming and climate change, which can make heat domes more frequent and intense in the future.
