Katie Rose Hobbs and Kirsten Elizabeth Pobjoy of British Aerosuperbatics Wingwalking Team perform ballet in the air during Huangguoshu Waterfalls Flight Conference on August 3, 2018 in Anshun, Guizhou Province of China. Huangguoshu Waterfalls Flight Conference including 18 aircraft from seven aerobatic teams from all over the world kicked off on Friday. (Photo by VCG via Getty Images)

Students from St Andrews University are covered in foam as they take part in the traditional Raisin Weekend in the Lower College Lawn, at St Andrews in Scotland on October 22, 2018. The “raisin weekend” stems from a gift of raisins (now flour and foam) traditionally given by a first year student to their academic “parents” in gratitude for their guidance. (Photo by Russell Cheyne/Reuters)

Cooler temperatures begin this week as a polar vortex brings much colder conditions with the chance of snow for Snowdonia, Ogwen Valley, North Wales on 22nd October 2018. The Ogwen Valley and Tryfan Mountain looking splendid in the Autumn sunrise. (Photo by DGDImages/Alamy Live News)

The Swiss Air Force Patrouille Suisse aerobatic team performs during the men's downhill race at the Alpine Skiing FIS Ski World Cup in Wengen, Switzerland, Saturday, January 19, 2019. (Photo by Anthony Anex/Keystone via AP Photo)

A tourist poses for a souvenir snap in front of autumn foliage in Pitlochry, Scotland, Britain on September 28, 2018. (Photo by Russell Cheyne/Reuters)

Heidi Klum and Bar Rafaeli attend the amfAR New York Gala 2019 at Cipriani Wall Street on February 6, 2019 in New York City. (Photo by Dimitrios Kambouris/amfAR/Getty Images)

A swimmer competes in Le Defi Monte-Cristo (Monte Cristo Challenge) swimming event at the Chateau d'If, off the coast of Marseille, southern France, on June 21, 2019. Created in 1999 and inspired by Alexandre Dumas' character of Edmond Dantes, the Monte Cristo Challenge will take place from June 21 to 23, 2019. (Photo by Boris Horvat/AFP Photo)

A man walks by as tourists take selfies on the French Riviera city of Nice on June 24, 2019, as temperatures soar to 33 degrees Celsius. Forecasters say Europeans will feel sizzling heat this week with temperatures soaring as high as 40 degrees Celsius (104 degrees Fahrenheit) in an “unprecedented” June heatwave hitting much of Western Europe. (Photo by Valery Hache/AFP Photo)