The effect is due to a meteorological phenomenon called 'inversion'

Visitors gather at a book shop during an annual book festival, celebrating Alexander Pushkin's birthday in Moscow, Russia, Sunday, June 4, 2023.

Now playing Next

Police rumble gang stealing antique books across Europe

Latest news bulletin | April 25th – Evening

Now playing Next

Latest news bulletin | April 25th – Evening

A white horse on the loose bolt through the streets of London near Aldwych, on Wednesday April 24, 2024.

Now playing Next

Several military horses run wild in London, injuring four people

FILE - Ukrainian soldiers fire at Russian positions from a US-supplied M777 howitzer in Kherson region, Ukraine, 9 January, 2023.

Now playing Next

Russian forces gain ground in eastern Ukraine

A local resident swims in the flooded street between houses in Orenburg, Russia

Now playing Next

WATCH: Russia and Kazakhstan continue to grapple with floods

Skies over southern Greece turned an orange hue on Tuesday, April 23, 2024.

Now playing Next

Athens turns orange as winds carry dust from Sahara desert

Lebanese Armenian holds a flag of Nagorno-Karabakh during a protest outside the Azerbaijani embassy in Beirut, Lebanon, on Thursday, Sept. 28, 2023.

Now playing Next

WATCH: Police in Armenia push protesters off road

Women from Syria in a refugee camp, outside of the capital Nicosia, in the eastern Mediterranean island of Cyprus, on Sunday, Sept. 10, 2017.

Now playing Next

Cyprus overwhelmed as number of refugee arrivals surges

Serbian President Aleksandar Vucic attends the government session in Belgrade, Serbia, Thursday, Dec. 15, 2022.

Now playing Next

Serbia president sorry for calling Slovenians 'disgusting'

A journalist gives Spanish socialist leader Pedro Sanchez and his wife Begona Gomez leave a polling station during the national elections in Madrid, Spain, Sunday, June. 25

Now playing Next

Judge asks for investigation into Spain PM's wife to be suspended

Italy's Prime Minister Giorgia Meloni shakes hands with President Sergio Mattarella at 79th anniversary of Liberation Day (Roberto Monaldo/LaPresse via AP)

Now playing Next

Italy marks anniveersary of fascist defeat amid TV censorship row

Updated: 23/08/2019 - 12:24

Video. Watch: River of clouds descends on Alpine valley

Inversion takes place when air temperature increases with height as opposed to decreasing at higher altitudes.

Read full article

More from world news

A view of Hope Hostel one of the locations where the asylum seekers from the U.K. are expected to arrive in the next 10-12 weeks in Kigali, Rwanda, Wednesday, April 24, 2024.

Now playing Next

Rwanda's Hope Hostel prepares for migrants from Britain

Young people protest in a march against student precarity on March 21st in Lisbon. They hold carnations, the symbol of the revolution.

Now playing Next

Portugal: 50 years after the revolution, are the carnations wilting?

FILE PHOTO - In this image provided by the U.S. Army, Army Tactical Missile System (ATACMS) on to the High Mobility Artillery Rocket System (HIMARS) in Queensland, Australia.

Now playing Next

US secretly sent ATACMS missiles to Ukraine

Members of the Abu Draz family inspect their house after it was hit by an Israeli airstrike in Rafah, southern Gaza

Now playing Next

Israel 'moving ahead' with Rafah offensive

Latest video

MEPs vote during a plenary session on Strasbourg, France, on April 24, 2024.

Now playing Next

EU Parliament leaders recall term's highs and lows at last sitting

French President Emmanuel Macron delivers a speech on Europe in the amphitheater of the Sorbonne University, April 25 in Paris. 2024.

Now playing Next

'Europe is mortal': Macron calls for more EU unity and sovereignty

In February, biomolecular engineers at Yonsei University in South Korea successfully integrated animal cells into rice grains in a bid to develop a sustainable future food.

Now playing Next

Would you try this lab-grown pink rice made with bovine cells?

Various of stranded whales and rescuers

Now playing Next

Mass stranding: Over 160 pilot whales beached in Western Australia

Sérgio Godinho in the "hot" times of the 1970s

Now playing Next

Sérgio Godinho's 25 April: From exile in Canada to freedom in Portugal

Drone unit Bakhmut.

Now playing Next

WATCH: Improvised Ukrainian drone unit in Russia-seized Bakhmut

Covered in prayer shawls, Jewish men of the Cohanim Priestly caste participate in a blessing Jerusalem's Old City, Thursday, April 25, 2024.

Now playing Next

Thousands of Jewish worshippers attend priestly blessing ceremony

Volkswagen CEO Oliver Blume speaks during a media event held by the Volkswagen Group a day before the auto show in Beijing.

Now playing Next

VW and other European electric car makers fight to catch up with China

'Portrait of Fräulein Lieser' by Austrian painter Gustav Klimt prior to an auction

Now playing Next

Lost portrait by Gustav Klimt sold for €30 million at auction

A porter carries tourists luggages outside the main train station in Venice, Italy, Wednesday 24 April 2024

Now playing Next

Venice fines tourists who don’t pay city entrance fee

Spanish Prime Minister Pedro Sanchez and his wife Begona Gomez arrive at 10 Downing Street in London, Dec. 3, 2019. A Spanish judge agreed Wednesday, April 24, 2024.

Now playing Next

Spanish PM Pedro Sanchez suspends public duties to 'reflect'

No, this video doesn't show the ICJ condemning Germany in Nicaragua's Gaza 'genocide' case

Now playing Next

No, this video doesn't show the ICJ condemning Germany in Gaza case

The Committee commemorating the 50th anniversary of 25 April has scheduled a parade for the afternoon of the 25th, which will start at Praça Marquês de Pombal, follow Avenida da Liberdade and end at Rossio

Now playing Next

50 years since the revolution, where is Portugal today?

Portuguese youth on 25 April 1974, by Alfredo Cunha

Now playing Next

Alfredo Cunha: The photographer who defined the Carnation Revolution

A Ukrainian serviceman from Code 9.2 unit known by call sign Mamay catches a drone at the frontline, few kilometres from Bakhmut, Donetsk region, Ukraine, 24/04/24.

Now playing Next

Ukraine deploys US long-range missiles for first time

Demonstrators hold up a banner with writing (Italian) "Lets free Ilaria Salis", in front of the Pantheon monument, in Rome, ON Feb. 14, 2024.

Now playing Next

Father of anti-Nazi activist: 'My daughter wants a fair trial'