On the blue sky, lots of white persistent airplane traces are visible from time to time. It could be water vapor, carbon dioxide and some other substances resulted from the burned fuel of the airplane. Or, maybe those traces could be chemtrails, according to the followers of conspiracy theory. Who knows what are these traces left by the airplane?
The image was made with a Nikon D40X camera and Nikon 55-200mm VR AF-S f/4-5.6G ED lens with the following settings: exposure time – 1/200 seconds, focal length – 55 mm, ISO – 200, F- number – 4.5