Last Thursday, December 14, cloud specialist Bastian Van Diedenhoven noticed curious patterns in the sky over Florida. The white stripes, captured by NASA's Aqua satellite in natural and false colors, were abandoned by aircraft.
“These are definitely airplane contrails. Such patterns are not typical of the atmosphere,”said Van Diedenhoven.
Condensation (or contrails) trails are a type of cirrus clouds that form in much the same way as in nature. The difference lies in the source of the ingredients. Aircraft exhaust contains an abundance of water vapor and fine particles. At high altitudes, where it is cold enough - about −39 ° C - water vapor can easily freeze on particles and form long, narrow clouds.
The blue areas in the second image indicate ice, which is consistent with the ice composition of the contrail. When the temperature and humidity of the air allows the ice crystals to remain solid, cirrus clouds can persist for about an hour and move with the winds. In this case, the relatively long life span, the unique shape and detachment of the contours have improved their visibility from space.
“These are not uncommon, but they are usually difficult to find,” explained Van Diedenhoven. - Often the plane has to turn circles to wait for the opportunity to land at the nearest airport. These patterns are also likely to be difficult to detect due to heavy air traffic and all the overlapping contours that occur when air conditions tend to create contrails.”
Another prime example of contrails was seen in March 2016, when semicircles were visible in the sky off the east coast of England. Van Diedenhoven determined that their source was a Royal Air Force aircraft, which he believed could be on a research flight.