What is ‘heat dome’, the phenomenon causing record temperatures across US?

‘Heat domes’ have also been associated with unusually warm periods in India, Bangladesh, China and some other Asian countries

By Prakriti Panda
Published: Saturday 22 April 2023
Photo: iStock

This week, places across the southwest and eastern parts of the United States recorded temperatures as warm as those seen in late June or early July, and the unusual warming was caused by a phenomenon known as ‘heat domes’, the news publication Washington Post reported. 

‘Heat domes’ are natural phenomena that have also been associated with unusually warm periods in India, Bangladesh, China and some other Asian countries. 

This season’s first heat dome set off heatwaves in as many as 48 states in the US and fears of wildfires loom large, the Washington Post story noted. 

Over the years, heat domes have created some of the most fatal heat waves in North America, among other regions. Creating records for some of the highest temperatures ever recorded in the continent, these waves have caused thousands of deaths.

Stopping heat domes from forming altogether is not possible, as they are a natural weather phenomenon. But as the threat of climate change continues to creep up on us, heat domes are getting more intense.

What is a heat dome?

A heat dome is a type of high-pressure system that forms over a large area in the atmosphere, and causes extremely hot and dry weather conditions. The system traps hot air and prevents it from flowing to rise and cool. This air then becomes compressed and heats up, leading to a dome-shaped area of hot air that can persist for several days or even weeks.

Heat domes can cause dangerous heat waves causing the temperatures to shoot up. In addition to temperatures which are highly unfavourable for humans, they can also lead to drought conditions and wildfire as the hot and dry weather can quickly dry out vegetation and make it more susceptible to catching fire.

Due to climate change, heat domes have not only become more frequent but also a lot more intense. The rising temperatures and changes in weather patterns are creating conditions that are assisting their formation.

While many people use ‘heat domes’ and ‘heat waves’ interchangeably, heat domes are just one of the atmospheric conditions that can contribute to the formation of a heat wave.

A heat wave is a prolonged period of excessively hot weather, often accompanied by high humidity. Heat waves can occur for a variety of reasons, including the presence of a heat dome. Heat waves can also occur without the presence of a heat dome, such as when warm, humid air masses from the tropics move to an area and stagnate for an extended period.

What causes a heat dome?

A number of meteorological elements work together to create a big high-pressure system in the atmosphere, which is what creates a heat dome. And with more studies being conducted to incur a deeper understanding on the climate, climate change has also been identified among the contributing factors to the increased frequency and intensity of heat domes.

Heat domes can be characterised by a large area of high pressure, a high pressure system is created by sinking air that warms as it descends. Under a heat dome, the air can become stagnant and not move much, which allows the heat to build up and intensify over time. High-pressure systems often bring clear skies, which means there is less reflection of sunlight and more absorption of heat. Locations with a lot of land and relatively dry air, such as plains and deserts, serve as a favourable condition for heat domes to form as well.

As the planet warms, it can create conditions that are more conducive to the formation of heat domes. Climate change has led to warmer background temperatures, exacerbating the high-pressure system. Regions that have become drier due to the same, can also create conditions that are beneficial to the formation of heat domes. Additionally, as the icebergs melt, the temperature and moisture patterns in the surrounding regions are influenced.

However, while these factors can create conditions for a heat dome to form, the intensity and duration of a heat dome can also be influenced by other factors, such as the amount of moisture in the air and the presence of other weather systems.

How does a heat dome impact the world?

Heat domes can have significant impacts on human health, particularly vulnerable populations such as elderly individuals, children and those with pre-existing health conditions that can be aggravated by extreme heat. 

Construction workers, farmers and agricultural workers, who work outdoors for long hours, are at increased risk of heat-related illnesses due to their prolonged exposure to high temperatures. People living in poverty are also more susceptible to the fatalities of heat domes as their houses are often built with heat-trapping surfaces such as concrete and asbestos.

Heat exhaustion occurs upon exposure to high temperature for extended periods of time, and can be characterised by symptoms such as dehydration, dizziness and nausea. In more severe cases, heat exhaustion can progress to a heat stroke, a medical emergency that can cause organ damage and even death. 

Hot weather can also put stress on the heart and lungs, particularly for those with pre-existing conditions like asthma or heart disease. Heatwaves have also been associated with increased rates of heart attacks, strokes and respiratory illnesses.

In addition to the impacts on human health, heat domes can also have other significant impacts on the environment. Droughts and wildfires are some of the most devastating bearings due to the hot and dry conditions, paired up with reduced rainfall and increased evaporation rates. 

Heat domes also cause damage to infrastructure such as roads and buildings, particularly if they were not designed to withstand such conditions.

How to combat heat domes?

Heat domes are a natural weather phenomenon and hence, stopping heat domes from forming altogether is not possible. However, there are steps that can be taken to mitigate their impacts and reduce the likelihood of them occurring as frequently or with as much severity. Some strategies are:

  1. Reducing greenhouse emissions: Transitioning to renewable energy sources, improving energy efficiency and promoting sustainable transportation, can be measures in achieving a reduction of greenhouse gas emissions, as it is critical to mitigating the impacts of heat domes in long terms.
  2. Investing in green infrastructure: Cities can invest in green infrastructure, such as parks, green roofs, and tree planting, which can help reduce the urban heat island effect and provide cooling benefits.
  3. Implementing building codes and standards: Building codes and standards can help ensure that new buildings are designed to withstand extreme heat and maintain indoor comfort during heat waves.
  4. Reducing heat-trapping surfaces: Cities can take steps to reduce the amount of heat-trapping surfaces, such as asphalt and concrete, which can exacerbate the urban heat island effect.
  5. Enhancing public education and outreach: Educating the public about the risks of extreme heat and how to stay safe during heat waves can help reduce the incidence of heat-related illness and mortality.

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.