HEAT DOME

1. Context

2. Key points

• According to the report, at least seven countries recorded their hottest January weather ever.
• These included Poland, Denmark, the Czech Republic, the Netherlands, Belarus, Lithuania and Latvia.
• Climatologists suggested that the temperatures surged to summer or springtime levels.
• For example, at Korbielów, a small village in Poland, the mercury reached 19 degree Celsius a temperature the region is more used to in May and 18 degree Celsius above the one degree Celsius yearly average for January.
• Meanwhile, in parts of Belarus, where temperatures usually remain around zero degree Celsius, they peaked at 16.4 degree Celsius on January 1.
• The continent is experiencing an extreme warm spell because of the formation of a heat dome over the region. 

3. What is Heat dome?

• A heat dome occurs when an area of high-pressure traps warm air over a region, just like a lid on a pot, for an extended period of time.
• The longer that air remains trapped, the more the sun works to heat the air, producing warmer conditions with every passing day.
• Heat domes generally stay for a few days but sometimes they can extend up to weeks, which might cause deadly heat waves.
• Scientists suggest that any region of high pressure, whether a heat dome or not, forces air to sink and once it reaches the ground, it gets compressed and becomes even warmer.
• Moreover, when air sinks, it gets drier and further raises the temperature of the area.

4. Relationship between heat domes and the jet stream

• The heat dome’s formation is related to the behaviour of the jet stream an area of fast-moving air high in the atmosphere.
• The jet stream is believed to have a wavelike pattern that keeps moving from north to south and then north again.
• Whenthese waves get bigger and elongated, they move slowly and sometimes can become
  stationary.
• This is when a high-pressure system gets stuck and leads to the occurrence of a heat dome.
• Although heat domes are likely to have always existed, researchers say that climate change may be making them more intense and longer.
• They suggest with the rising temperatures, it is expected that the jet stream will become more wavy and will have larger deviations, causing more frequent extreme heat events.

5. Previous instances of heat domes

• In 2021, a heat dome formed over western Canada and the US, causing deadly heat waves.
• Portland city in Oregon, US, saw the mercury rise to 46 degree Celsius while the temperature in Washington hit 49 degree Celsius.
• In Lytton in British Columbia, temperatures soared to over 46 degree Celsius.
• Hundreds of people are believed to have died due to this extreme weather event.
• Subsequently, a 2022 study found that this heat dome was amplified by climate change and it could become a once-in-10-year event if global temperatures aren’t kept under two degree Celsius above pre-industrialisation levels.

• Another heat dome settled over the US in September 2022 and raised temperatures to a new high. The extreme heat fueled wildfires and stressed the power grid. 

For Prelims & Mains