A photographer tested the concentration of several pairs of dogs as he captured their reactions to treat time in a series of shots. Christian Vieler, 47, of Waltrop, Germany, has been a professional dog photographer since 2016. He came up with the idea of snapping two dogs catching treats simultaneously. Here: Basset Hounds. (Photo by Vieler Photography/Caters News Agency)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

Women carry a portable shrine, a Mikoshi, through a street in Tokyo's Asakusa district during the Sanja festival, Japan, May 15, 2016. (Photo by Thomas Peter/Reuters)

Members of the Wasteland Warriors from the movie “MadMax” pose during the Wacken Open Air festival on August 4, 2016 in Wacken, Germany. Wacken is a village in northern Germany with a population of 1,800 that has hosted the annual festival, which attracts heavy metal fans from around the world, since 1990. (Photo by Alexander Koerner/Getty Images)

Smoke plumes rise from Mount Etna, one of the most active volcanoes in the world in Sicily, Italy on June 28, 2016. (Photo by Etna Walk/Rex Feature/Shutterstock)

Filipino barefoot Catholics carry a replica of the Black Nazarene during a procession ahead of the Black Nazarene feast day celebrations in Manila, Philippines, 07 January 2016. The procession of the Black Nazarene is expected to draw millions of barefooted Catholic devotees to Manila on 09 January, according to a Manila police official. (Photo by Francis R. Malasig/EPA)

A man carries an injured woman in a site hit by what activists said were airstrikes carried out by the Russian air force in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria January 9, 2016. At least 70 people died in what activists said where four vacuum bombs dropped by the Russian air force in the town of Maaret al-Numan; other air strikes where also carried out in the towns of Saraqib, Khan Sheikhoun and Maar Dabseh, in Idlib. (Photo by Khalil Ashawi/Reuters)

A Palestinian throws snow at his wife during a snow storm in West Bank old city of Hebron, January 26, 2016. (Photo by Mussa Qawasma/Reuters)