Clouds gather as walkers pause atop a ridge in Mountain View, California January 7, 2016. (Photo by Noah Berger/Reuters)

Eritrean refugee children play at Mai-Aini refugee camp near the Eritrean boarder in the Tigrai region in Ethiopia February 10, 2016. Each month as many as 5,000 people flee Eritrea according to U.N. figures, estimates the Eritrean government disputes. The government puts the population at about 3.6 million, while other estimates suggest it could be almost double that. (Photo by Tiksa Negeri/Reuters)

A boy bursts a soap-bubble at Gorky Park in Moscow on July 19, 2017. (Photo by Mladen Antonov/AFP Photo)

The Villarica volcano erupts near Pucon, Chile, early Tuesday, March 3, 2015. The Villarica volcano erupted Tuesday around 3 a.m. local time (06:00 GMT), according to the National Emergency Office, which issued a red alert and ordered evacuations. (Photo by Aton Chile/AP Photo)

Labourers who work nearby nap on a road as cars drive past in Chongqing Municipality, July 23, 2013. (Photo by Reuters/Stringer)

In this Thursday, April 11, 2013 photo, an Afghan woman peers through the the eye slit of her burqa as she waits to try on a new burqa in shop in the old town of Kabul, Afghanistan. (Photo by Anja Niedringhaus/AP Photo)

The giant inflatable Rubber Duck installation by Dutch artist Florentijn Hofman floats on the Parramatta River, as part of the 2014 Sydney Festival, in Western Sydney, January 10, 2014. The creation is five stories tall and five stories wide and has been seen floating in various cities around the world since 2007. (Photo by Jason Reed/Reuters)

Yaks head towards the Everest base camp in Solukhumbu District April 28, 2014. (Photo by Navesh Chitrakar/Reuters)