What is the ‘heat dome’

Contact Counsellor

Last Updated03/07/2021

The temperatures reported from the Pacific northwest and some parts of Canada are part of a "historic" heat wave.
This is a result of a phenomenon referred to as a "heat dome".
The phenomenon begins when there is a strong change (or gradient) in ocean temperatures.

To understand what causes a heat dome, one should liken the Pacific Ocean to a large swimming pool in which the heater is turned on.
Once the heater is on, the portions of the pool close to the heating jets will warm up faster and therefore, the temperature in that area will be higher.
In the same way, the western Pacific ocean’s temperatures have increased in the past few decades and are relatively more than the temperature in the eastern Pacific.
This strong change in ocean temperature from the west to the east is what a team of scientists believe is the reason for the heat dome.

which is when the atmosphere traps heat at the surface, which encourages the formation of a heat wave.

HD also prevents clouds from forming, allowing for more radiation from the sun to hit the ground.
A heat dome is effectively what it sounds like - an area of high pressure that parks over a region like a lid on a pot, trapping heat. They are more likely to form during La Niña years like 2021, when waters are cool in the eastern Pacific and warm in the western Pacific.

A heat wave is a period of abnormally high temperatures, more than the normal maximum temperature that lasts for more than two days.
Heat waves typically occur between March and June, and in some rare cases even extend till July.
Heat waves can occur with or without high humidity and have the potential to cover a large area, “exposing a high number of people to hazardous heat.”

It cannot be said for sure if the heat wave is a direct result of global warming.
Scientists are usually wary of linking climate change to any contemporary event mainly because of the difficulty in completely ruling out the possibility of the event having been caused by some other reason, or being a result of natural variability.

However, scientists who have been studying the climate tend to agree that the heat waves occurring today are more likely to be a result of climate change for which humans are responsible.

Statistically speaking, this would be a once-in-a-1,000-year occurrence in a normal climate.
But our climate is no longer normal: it is being heated by human-caused climate change. So these once nearly impossible heat waves will become not only possible, but more probable, in the coming years and decades.

As long as the body is producing sweat, which is then able to evaporate quickly, the body will be able to remain cool even under high temperatures.
Wet-bulb temperature (WBT) is a limit that considers heat and humidity beyond which humans can not tolerate high temperatures.
Temperatures beyond WBT can cause heat related illnesses including heat stroke, heat exhaustion, sunburn and heat rashes. Sometimes these can prove fatal.

The trapping of heat can also damage crops, dry out vegetation and result in droughts.
The sweltering heat wave will also lead to rise in energy demand, especially electricity, leading to pushing up rates.
The heat domes can also act as fuel to wildfires, which destroys a lot of land area in the US every year.
Those living without an air conditioner see the temperatures of their homes rising to unbearably high, leading to sudden fatalities.
In decades to come, the climate scientists expect more days of severe heat wave.