On February 19, 2015, users of popular social networks Instagram and Twitter were surprised at the appearance of clouds of an unusual shape in the sky over Vladivostok. The photographs, which appeared on the Internet more than a dozen, and the videos can be seen, captured very remarkable "white circles", which immediately began to be attributed to extraterrestrial origin.
Unusual clouds appeared over Vladivostok at lunchtime and instantly became the focus of camera lenses and gadgets of many townspeople. Some have expressed concern about whether the UFO has left its mark. Others argued that the plane could leave such lanes.
Unfortunately, the editors of RIA PrimaMedia were unable to receive comments from meteorologists or physicists today, which is associated with such an unusual shape of clouds. But they are sure that everything can be explained by the laws of physics, for example, by the very "Prandtl-Glauert effect", which Internet users most often recalled in comments to unusual photos on social networks. We are talking about the formation of clouds after the plane. Still an airplane?
As the reference books write, the appearance of a cloud due to the Prandtl-Glauert effect depends not only on the speed of the aircraft, but also on the temperature and humidity of the air. In conditions of normal or slightly high humidity, a cloud forms only at speeds close to the speed of sound. In very high humidity conditions, the effect can also be observed at lower (transonic, "transonic") speeds.