Explained: What is a heat dome? Why Pacific Northwest is witnessing record-breaking temperatures

New Delhi, July 01: The Pacific north-west, known for its moderate climate, is gripped in an unprecedented "heat dome". The temperatures have driven millions of people to the region's beaches, pools and air-conditioned hotels, as residents in a region with few air-conditioned households try desperately to get some relief.

Behind the misery is a weather phenomenon known as a heat dome. The weather experts have blamed the heat dome effect for the sudden rise in temperature.

But what exactly is a heat dome?

A heat dome occurs when the atmosphere traps hot ocean air like a lid or cap.
The scorching heat is ensnared in what is called a heat dome. This happens when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets trapped under the high-pressure "dome."

Research from the National Oceanic and Atmospheric Administration (NOAA) shows hey 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.

So what triggers heat domes?

A team of scientists funded by the NOAA MAPP Program investigated what triggers heat domes and found the main cause was a strong change (or gradient) in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter.

How unusual is the heat wave in the Pacific Northwest?

Heat domes do occur periodically in the Pacific Northwest and the phenomenon is not new. The intensity of this heat dome is what is unique, though, making some wonder whether there is a link to climate change.

Effects of heat domes

The sweltering heat wave will lead to rise in energy demand, especially electricity, leading to pushing up rates. The trapping of heat can also damage crops, dry out vegetation and result in droughts.