A man carrying an umbrella is seen through a window covered with rain drops during a wet day in Colombo, Sri Lanka September 24, 2019. REUTERS/Dinuka Liyanawatte

A lightning storm is seen from the German NGO Sea-Eye migrant rescue ship 'Alan Kurdi' off the Spanish island of Majorca in the western Mediterranean Sea, September 14, 2019. REUTERS/Darrin Zammit Lupi

A lightning storm is seen from the German NGO Sea-Eye migrant rescue ship 'Alan Kurdi' off the Spanish island of Majorca in the western Mediterranean Sea, September 14, 2019. REUTERS/Darrin Zammit Lupi

The Frauenkirche (Church of our Lady), the City Hall and the Christmas market on Marienplatz are seen behind raindrops on a fence in Munich, Germany, December 23, 2018. REUTERS/Andreas Gebert

The Frauenkirche (Church of our Lady), the City Hall and the Christmas market on Marienplatz are seen behind raindrops on a fence in Munich, Germany, December 23, 2018. REUTERS/Andreas Gebert

The Frauenkirche (Church of our Lady), the City Hall and the Christmas market on Marienplatz are seen behind raindrops on a fence in Munich, Germany, December 23, 2018. REUTERS/Andreas Gebert

People walk in the rain as pictured through a window in the Manhattan borough of New York City, New York, U.S., December 21, 2018. REUTERS/Carlo Allegri

Ships are seen near the Azov Sea port of Mariupol, Ukraine December 2, 2018. REUTERS/Gleb Garanich TPX IMAGES OF THE DAY

A general view shows the city of Sofia covered in smog, Bulgaria, December 1, 2018. Picture taken December 1, 2018. REUTERS/Stoyan Nenov

A general view shows the city of Sofia covered in smog, Bulgaria, December 1, 2018. Picture taken December 1, 2018. REUTERS/Stoyan Nenov

A general view shows the city of Sofia, Bulgaria, December 1, 2018. Picture taken December 1, 2018. REUTERS/Stoyan Nenov

A general view shows the city of Sofia covered in smog, Bulgaria, December 1, 2018. Picture taken December 1, 2018. REUTERS/Stoyan Nenov

A view shows protesters wearing yellow vests, a symbol of a French drivers' protest against higher diesel taxes, during clashes as part of a demonstration at the Place de l'Etoile in Paris, France, December 1, 2018. REUTERS/Stephane Mahe

People rest near the frozen Azov Sea in Mariupol, Ukraine December 1, 2018. REUTERS/Gleb Garanich

A pier on the frozen Azov Sea is seen in Mariupol, Ukraine December 1, 2018. REUTERS/Gleb Garanich

A pier on the frozen Azov Sea is seen in Mariupol, Ukraine December 1, 2018. REUTERS/Gleb Garanich

A general view shows protesters wearing yellow vests, a symbol of a French drivers' protest against higher diesel taxes, during clashes as part of a demonstration at the Place de l'Etoile in Paris with the Eiffel tower in the background, France, December 1, 2018. REUTERS/Stephane Mahe

A general view shows protesters wearing yellow vests, a symbol of a French drivers' protest against higher diesel taxes, during a demonstration at the Place de l'Etoile in Paris, France, December 1, 2018. REUTERS/Stephane Mahe

A general view shows protesters wearing yellow vests, a symbol of a French drivers' protest against higher diesel taxes, during a demonstration at the Place de l'Etoile in Paris with the Eiffel tower in the background, France, December 1, 2018. REUTERS/Stephane Mahe

The Berezina river is seen near the village of Krasnaye, Belarus November 29, 2018. REUTERS/Vasily Fedosenko

Broadcasting tower "Kopitoto" is seen through clouds at Vitosha mountain, near Sofia, Bulgaria, November 29, 2018. REUTERS/Stoyan Nenov

The Thames Barrier fades into early morning fog on the Thames, in London, Britain, November 27, 2019. REUTERS/Steven Watt

The Houses of Parliament are seen on a foggy morning in London, Britain, November 27, 2018. REUTERS/Toby Melville

The Houses of Parliament are seen on a foggy morning in London, Britain, November 27, 2018. REUTERS/Toby Melville

Trees are silhouetted at sunrise during a foggy winter morning at Khokana in Lalitpur, Nepal November 27, 2018. REUTERS/Navesh Chitrakar

A man carrying hay stacks walks along the field during a foggy winter morning at Khokana in Lalitpur, Nepal November 27, 2018. REUTERS/Navesh Chitrakar

Snow covered trees are seen in fog in central Kiev, Ukraine November 26, 2018. REUTERS/Gleb Garanich

A pigeon flies in fog at a park in central Kiev, Ukraine November 26, 2018. REUTERS/Gleb Garanich

A general view of the city's skyline in Tetovo, Macedonia, October 29, 2018. Picture taken October 29, 2018. REUTERS/Ognen Teofilovski

A general view of the city's skyline in Tetovo, Macedonia, October 29, 2018. Picture taken October 29, 2018. REUTERS/Ognen Teofilovski

A general view shows the sea along the Mazatlan coast as Hurricane Willa approaches the Pacific beach resort, Mexico October 23, 2018. REUTERS/Henry Romero

A general view shows the sea along the Mazatlan coast as Hurricane Willa approaches the Pacific beach resort, Mexico October 23, 2018. REUTERS/Henry Romero

A red flag, warning of dangerous conditions, is seen at a closed beach in Mazatlan as Hurricane Willa approaches the Pacific beach resort, Mexico October 23, 2018. REUTERS/Henry Romero

A red flag, warning of dangerous conditions, is seen at a closed beach in Mazatlan as Hurricane Willa approaches the Pacific beach resort, Mexico October 23, 2018. REUTERS/Henry Romero

A general view of buildings in Shanghai city amid heavy smog in Shanghai, China October 18, 2018. REUTERS/Aly Song

The Suchitlan Lake is seen after rain from the town of Suchitoto, El Salvador October 7, 2018. REUTERS/Jose Cabezas

The Quezalapa river is seen after rain in the town of Cinquera, El Salvador October 7, 2018. REUTERS/Jose Cabezas

A surfer lays in the sea at the water edge along the beach in Brighton, Britain September 18, 2018. REUTERS/Hannah McKay

A surfer walks along the beach in Brighton, Britain September 18, 2018. REUTERS/Hannah McKay

A surfer walks along the beach in Brighton, Britain September 18, 2018. REUTERS/Hannah McKay

A man walks along a road during fog at dawn in Cox's Bazar, Bangladesh, March 31, 2018. Picture taken March 31, 2018. REUTERS/Clodagh Kilcoyne

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

Birds are seen flying as St Paul's Cathedral and skyscrapers in the City of London are seen at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

Skyscrapers in the City of London are seen at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The dome of St Paul's Cathedral and construction cranes are silhouetted by the rising sun at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

Birds are seen flying as St Paul's Cathedral and skyscrapers in the City of London are seen at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

Birds are seen flying as St Paul's Cathedral and skyscrapers in the City of London are seen at dawn in London, Britain, August 5, 2018. REUTERS/Toby Melville

The sun rises behind skyscrapers in the City of London in London, Britain, August 4, 2018. REUTERS/Toby Melville TPX IMAGES OF THE DAY

The sun rises behind skyscrapers in the City of London in London, Britain, August 4, 2018. REUTERS/Toby Melville

The sun rises behind St. Paul's Cathedral in London, Britain, August 4, 2018. REUTERS/Toby Melville

The sun rises behind skyscrapers in the City of London in London, Britain, August 4, 2018. REUTERS/Toby Melville

The sun rises behind skyscrapers in the City of London in London, Britain, August 4, 2018. REUTERS/Toby Melville

Skyscrapers in the City of London are seen at dawn in London, Britain, August 4, 2018. REUTERS/Toby Melville

A passenger aircraft flies past the sun at sunset during a hot summer day in Malaga, southern Spain, as temperatures soar across Europe, August 3, 2018. REUTERS/Jon Nazca

An abandoned house is seen in the village of La Estrella, Spain, June 26, 2018. REUTERS/Susana Vera SEARCH "SPAIN DEPOPULATION" FOR THIS STORY. SEARCH "WIDER IMAGE" FOR ALL STORIES.