A man salts a downtown sidewalk in Washington, Thursday, March 5, 2015, as snow begins to fall. The U.S. federal government said its offices in the Washington area will be closed Thursday because of a new round of winter weather expected in the region. The Office of Personnel Management said non-emergency personnel in and around Washington were granted excused absences for the day. Emergency employees and telework-ready employees were expected to work. (AP Photo/Andrew Harnik)

Canada's Mandy Marchak (R) is taken down by France's Pauline Biscarat during the final match of the Hong Kong Sevens rugby women's invitational cup in Hong Kong March 28, 2014. (Photo by Tyrone Siu/Reuters)

Planes land in fog at Heathrow Airport, west London, as heavy fog covers a many parts of the south east, on April 1, 2014. (Photo by Steve Parsons/PA Wire)

The Euro sculpture is partially reflected in a puddle on a cobblestone pavement in front of the headquarters of the European Central Bank in Frankfurt on Jan. 21. (Kai Pfaffenbach/Reuters)

Green algae sits on a beach in Kuwait City, Kuwait, 28 February 2017. The formation of green algae is a normal phenomenon that occurs every year at the shores of Kuwait. (Photo by Raed Qutena/EPA)

This picture taken on October 20, 2016 shows students practising wushu at the Tagou martial arts school in Dengfeng. China is investing hugely in football training and has vowed to have 50 million school- age players by 2020, as the ruling Communist party eyes “football superpower” status by 2050. (Photo by Nicolas Asfouri/AFP Photo)

Protesters clad in improvised protective gear prepare for a clash with police in central Kiev, Ukraine, Monday, January 20, 2014. After a night of vicious streets battles, anti-government protesters and police clashed anew Monday in the Ukrainian capital Kiev. (Photo by Evgeny Feldman/AP Photo)

Two men fight in San Jose, Costa Rica, during the Women's Day on March 8, 2014. (Photo by Jeffrey Arguedas/EFE/SIPA Press)