A Chinese woman wears a mask to protect from particles blown in during a sandstorm as she walks in the street on May 4, 2017 in Beijing, China. Sandstorms are common in northern China during the spring season and are caused when heavy winds from Mongolia in the north brings sand and pollutants that can blanket Chinese cities and cause air quality to deteriorate. (Photo by Kevin Frayer/Getty Images)

Chinese soldiers leave after Chinese President Xi Jinping inspected troops of People's Liberation Army (PLA) Hong Kong Garrison at the Shek Kong Barracks in Hong Kong, Friday, June 30, 2017. Xi landed in Hong Kong Thursday to mark the 20th anniversary of Beijing taking control of the former British colony, accompanied by a formidable layer of security as authorities showed little patience for pro-democracy protests. (Photo by Kin Cheung/AP Photo)

A herd of elephants cross a road that passes through the flooded Kaziranga National Park in the northeastern state of Assam, India, July 12, 2017. (Photo by Anuwar Hazarika/Reuters)

The symbol for “One Orlando” is spelled out at a makeshift memorial at Lake Eola in downtown Orlando, Fla., Saturday, June 18, 2016. Nearby, visitors lit candles and prayed at a larger memorial, at the Dr. Phillips Center for the Performing Arts, to mourn the victims of the Pulse massacre. (Photo by Joe Burbank/Orlando Sentinel via AP Photo)

A Filipino girl is carried along a flooded road in suburban Mandaluyong, east of Manila, Philippines, as monsoon downpours intensify while Typhoon Nepartak exits the country on Friday, July 8, 2016. In the Philippine capital, Manila, and outlying provinces, classes in many schools were suspended and at least six flights, including one scheduled to come from Taiwan, were canceled because of stormy weather and floods following monsoon downpours intensified by the typhoon, Filipino officials said. (Photo by Aaron Favila/AP Photo)

A baby dives as his mother holds on tightly during a water baby class in Odessa, Ukraine on August 6, 2016. (Photo by Andrey Nekrasov/Barcroft Images)

Tim Anderson final balanced rock stack in the Llano River. Tim Anderson, rock balancing “pro” from Pennsylvania, carefully worked to balance his stack on a dry spot in the Llano river Saturday March 12, 2016. He was an honored guest of the festival and enjoyed visiting Texas so he came for another year. The river was higher this year because of the rains so the balancers could not get to the better rock that were available last year. (Photo by Nell Carroll/American-Statesman)

The front wheels of a tractor, pulling a trailer overloaded with sugarcane, are seen lifted off the ground as it passes through the streets of Karor Lan Esan, Pakistan December 6, 2015. (Photo by Caren Firouz/Reuters)