Explainer-What is a 'heat dome' and how does it power heatwaves?
A man catches the sun next to a pile of deck chairs in Green Park as an amber heat warning was issued in London, Britain, June 30, 2025. REUTERS/Kevin Coombs
Tourists stand in front of a cooling fan installed outside the Colosseum in during the heatwave in Rome, Italy, June 30, 2025. REUTERS/Remo Casilli
FILE PHOTO: A tourist drinks water during his visit at the Parthenon temple atop the Acropolis hill, as a heatwave hits Athens, Greece, June 27, 2025. REUTERS/Stelios Misinas/File Photo
Explainer-What is a 'heat dome' and how does it power heatwaves?
BRUSSELS - Large parts of Western Europe were in the grip of a severe heatwave on Monday, with temperatures breaching 40 degrees Celsius (104 degrees Fahrenheit) in Spain and wildfires breaking out in France.
Scientists said the extreme temperatures in the region - with Britain and the Netherlands among the countries affected - were related to a "heat dome" over continental Europe.
Here's what that means:
WHAT IS IT?
A heat dome is an area of high-pressure air in the atmosphere which gets stuck in place over a region because atmospheric dynamics around it block it from moving.
It works like putting a lid on a boiling pot. The high-pressure system traps hot air below it, which heats up and compresses to form a "dome". This intensifies heat and prevents the formation of clouds, allowing even more radiation from the sun to reach the ground below.
A heat dome results in clear, sunny days, and still conditions with little cooling wind.
It builds up over time - the longer the "dome" is stuck over one area, the more that dark surfaces below, such as roads and buildings, absorb and retain heat, and the more that the ground dries out. It also makes wildfires more likely, because the heat dries out vegetation.
Such systems can last for days to weeks. Forecasts suggest this one will dissipate in a few days, which happens when another weather system, such as a storm or a low-pressure system of cooler conditions, pushes the high-pressure system away.
IS IT LINKED TO CLIMATE CHANGE?
Heat domes are not a new type of weather pattern. A specific attribution study would be needed to confirm in what ways the heat dome Western Europe is currently experiencing was specifically affected by climate change.
But scientists said the severity of the temperatures and the early timing of the current heatwave in Western Europe tally with how climate change is known to affect heatwaves.
Scientists have already confirmed that climate change is making heatwave events more intense, more frequent and more widespread.
The build-up of greenhouse gas emissions in the atmosphere - which mostly come from burning fossil fuels - means the planet's average temperature has increased over time. This increase in baseline temperatures means that when a heatwave comes, temperatures can surge to reach higher peaks.
Spain has likely just had its hottest June on record, according to national meteorological service AEMET, while the southeastern town of Mora in Portugal on Sunday set a new national record-high temperature for June, of 46.6 C.
Today, the planet's long-term global average temperature has risen nearly 1.3 degrees Celsius since the Industrial Revolution in the 19th century, when countries began burning fossil fuels on an industrial scale.
Europe is the world's fastest-warming continent, heating up at twice the global average.
WILL WE GET MORE?
Climate change is making extreme heatwaves like the current one occur earlier in the year, and persist into later months.
Parts of the United States also faced extreme temperatures caused by a heat dome in the last two weeks.
While it is hard to predict specific heatwaves months in advance, current seasonal forecasts for July, August and September indicate Europe is highly likely to experience a warmer than average summer, Dr Samantha Burgess, Strategic Lead for Climate at the EU's Copernicus Climate Change Service, told Reuters. REUTERS
Join ST's Telegram channel and get the latest breaking news delivered to you.
Try Our AI Features
Explore what Daily8 AI can do for you:
Comments
No comments yet...
Related Articles
Straits Times
11 hours ago
- Straits Times
Greece shuts Acropolis for part of day as heat soars, bans outdoor work
Sign up now: Get ST's newsletters delivered to your inbox People stand in a shade while visiting the Acropolis, at the start of a 3-days heatwave with temperatures expected to overpass 40 Celsius degrees, in Athens, Greece, July 7, 2025. REUTERS/Louisa Gouliamaki ATHENS - Greece shut the Acropolis for several hours in the afternoon on Tuesday, as the Mediterranean country baked in its second major heatwave of the season, with temperatures set to soar as high as 41 degrees Celsius (107.6 degrees Fahrenheit). Last week, large parts of Western Europe sweltered in a severe heatwave that left 8 dead and triggered forest fires and health alerts across the region. In Athens, temperatures were expected to reach 38 C, forcing authorities to close the Acropolis, its most visited ancient site, on a rocky hill offering barely any shade, at midday from 1000 GMT until 1400 GMT. Defying the heat, some tourists visited the monument before it shut. "It's extremely hot. So yeah, we had to take extra measures. We have little fans for the children. I have the hat, the glasses. We've been drinking lots of water," said John Howell, 58, a Scottish tourist. With hot air and humidity worsening conditions, authorities ordered some businesses in Thessaloniki, Greece's second largest city, and other areas on the mainland and southern Peloponnese peninsula, to limit outdoor work for employees in the afternoon. Builders, food delivery riders, couriers and shipyards workers are among those having to pause work from midday until 5 p.m. to avoid heat stress, the labour ministry said. Top stories Swipe. Select. Stay informed. Singapore NDP celebrations to be held at 5 heartland sites, including Bishan and Punggol, on Aug 10 Singapore NDP 2025: Tank that bumped into traffic light lost steering and braking power due to faulty part Singapore Keep citizens at the centre of public service, Chan Chun Sing tells civil servants Singapore SIA flight from Brisbane to Singapore diverted to Perth due to technical issue Singapore New Draft Master Plan could reignite developers' interest to buy land Business Great Eastern could resume trading after delisting vote fails to pass; OCBC's second offer lapses Asia China warns Trump on tariffs, threatens retaliation on supply chain deals Multimedia 'I suspect he's cheating': She finds proof when spouses stray The heatwave conditions will continue until Wednesday, the Greek meteorological service said, and authorities in the wider Athens and other areas will be on alert for wildfires as gale-force winds were expected. Worldwide, 2024 was the warmest year on record, with global temperatures exceeding 1.5 Celsius above the pre-industrial era for the first time. Greece, which sits on Europe's southernmost edge, also had its warmest winter and summer last year on record, incuding a 16-day heatwave in July, the longest ever, according to scientists. REUTERS
Straits Times
12 hours ago
- Straits Times
More than 18,000 people in lockdown as wildfire rages in Catalonia
Sign up now: Get ST's newsletters delivered to your inbox A helicopter helps to extinguish an ongoing wildfire in Xerta, which is one of the confined villages in the Tarrragona province in Catalonia, Spain, July 8, 2025. REUTERS/Nacho Doce XERTA, Spain - Spanish authorities ordered more than 18,000 residents of the northeastern Tarragona province to remain indoors on Tuesday and several dozen were evacuated as a wildfire raged out of control, consuming almost 3,000 hectares (7,413 acres) of vegetation. Large parts of Spain are on high alert for wildfires after the country experienced its hottest June on record. Two people died in a wildfire on July 1 in the region of Catalonia where Tarragona is located. The latest fire broke out early on Monday in a remote area near the village of Pauls, where strong winds and rugged terrain have hampered firefighting efforts, authorities said. An emergency military unit was deployed early on Tuesday alongside more than 300 firefighters working in the area. "Since midnight, firefighters have been battling the blaze with gusts of wind reaching up to 90 kilometres per hour (56 miles per hour)," Catalonia's regional firefighting service said, adding that the strong Mistral wind was expected to ease by the afternoon. Overnight, fire engines raced the winding roads of the Pauls Mountains, surrounded by flames, as crews assessed and tried to contain the blaze. In the neighbouring villages of Xerta and Aldover, residents spent a sleepless night as the flames threatened their homes. "(There has been) a lot of fear and a lot of crying because we are already on the edge of the fire. Last night, because of the wind that was blowing the fire and the smoke, we couldn't leave our house. Terrible, this has never been seen before," Rosa Veleda, 76, told Reuters. Top stories Swipe. Select. Stay informed. Singapore NDP celebrations to be held at 5 heartland sites, including Bishan and Punggol, on Aug 10 Singapore NDP 2025: Tank that bumped into traffic light lost steering and braking power due to faulty part Singapore SIA flight from Brisbane to Singapore diverted to Perth due to technical issue Singapore New Draft Master Plan could reignite developers' interest to buy land Singapore AI cannot supplant learning, it must enable it: Desmond Lee Asia China warns Trump on tariffs, threatens retaliation on supply chain deals Multimedia 'I suspect he's cheating': She finds proof when spouses stray Opinion Here's what happened after some US schools started locking up students' phones Authorities said they had prevented the fire from spreading across the Ebro River, which would have worsened the situation. Approximately 30% of the affected area lies within the Ports Natural Park, and officials are investigating the fire's origins. REUTERS
Straits Times
12 hours ago
- Straits Times
Seoul scorches at 37.8 deg C, highest early-July temperature ever recorded
Sign up now: Get ST's newsletters delivered to your inbox A woman walks past a structure showing that the mercury shot up to an intraday high of 37 deg C in Seoul on July 8. SEOUL - The temperature in Seoul reached 37.8 deg Celsius as of 3.15pm on July 8 (2.15pm Singapore time), the highest number ever recorded in the South Korean capital during the July 1–10 period since records began. The 37.1 deg C as of 2pm had already broken the previous highest temperature observed by the Seoul Meteorological Observatory for the same period, which was 36.8 deg C on July 9, 1939. This was 86 years ago and before the South Korean government was even officially established on Aug 15, 1948. Modern weather observation in Korea began in October 1907, meaning records for July temperatures can be traced back to the summer of the following year. Seoul has been hit this year with unusually early summer heat, with the Korea Meteorological Administration issuing the season's first heat wave at 10am on Monday. That was 18 days ahead of 2024, when the first heat wave warning was issued on July 25. A heat wave warning is issued when the day's high temperature is expected to reach a minimum of 35 deg C for two or more consecutive days. Meanwhile, a KMA report showed that the average temperature last month was 22.9 deg C, making it the hottest June on record and 0.2 deg C higher than 2024. Other regions across the country have also set record high weathers for early July, with temperatures of 40.2 deg C and 40.1 deg C being recorded each in Gwangmyeong and Paju, both in Gyeonggi Province. It was the first time a temperature went over 40 deg C in July, as the heat usually peaks in August in Korea. THE KOREA HERALD/ ASIA NEWS NETWORK
