ナショナルジオグラフィックさんのインスタグラム写真 - (ナショナルジオグラフィックInstagram)「Video and photos by Babak Tafreshi @babaktafreshi | Following on my post on the elusive red sprite phenomenon, this is a rare timelapse video of what I experienced near midnight on May 2 in West Texas. An atmospheric puzzle, they are large-scale electrical discharges occurring in clusters above the troposphere, about 50 to 90 kilometers (30–55 miles) high. These discharges occur high above enormous thunderstorm clouds. The video briefly freezes on the sprite moments so you can better see them; therefore, they appear similar to the length of time visible in real life but the time between them is about 100 times faster—otherwise the video would be one hour long in real time. To the naked eye, the sprites are colorless, featureless flashing patches of grey, and most people would miss them. Here I used a fast lens at wide-open aperture and high ISO to reveal them. Soundtrack is a courtesy of Ali Raini, from the Fragmented Future album. Follow me @babaktafreshi for more stories under stars. #redsprites #atmospheric #timelapse #twanight」7月4日 3時14分