As a heat wave exceeding 40 degrees Celsius continues to persist in southern Europe, an unusual weather phenomenon is happening in Portugal that has drawn attention.
According to reports from the Associated Press and the French newspaper Le Figaro on the 1st, a massive cloud resembling a giant roll appeared in some areas along the northern and central coasts of Portugal on the 29th of last month.
Videos capturing the scene on the beach at that time spread on social media. As the enormous mass of cloud rolled in from the ocean towards the beach, tourists who had come to the beach for the weekend were seen panicking, mistaking it for a tsunami.
One X (formerly Twitter) user shared a photo taken at the time, noting, "It was really hard to believe I was seeing this cloud. It felt like a tsunami out of a movie."
This cloud is referred to as a roll cloud in English and is also known in Korea as a giant roll cloud.
Climate expert Mario Marquez explained to APTN that for such a cloud formation to occur, conditions of wind, temperature, and humidity must all be met.
He stated, "During the day, the surface heats up with hot air present, and as evening approaches, cold air moves in, pushing the hot air upward," adding, "In this process, clouds form and roll along the ocean like tubes along the coastline."
He further noted, "It may look frightening to someone who has never seen it before, but in reality, it's just a cloud," adding that such phenomena are more commonly observed in areas like Australia.
On the day the cloud was spotted, temperatures in the Mora region of Portugal soared to 46.6 degrees Celsius, marking an unprecedented heat wave across the nation. This is the highest recorded temperature for June, surpassing the previous record of 45.4 degrees set just the day before.
In southern Spain's El Granado, the mercury also hit 46 degrees, setting a new record for the highest temperature in June.
The cause of this heat wave has been identified as a 'heat dome' forming from Africa. This hot, dry heat dome has recently affected areas from North Africa to southern Europe and is expanding its influence northward to northern Europe.