sprite

In earth science, rare thunderstorm-related luminous flash. Sprites occur in the mesosphere, at altitudes of 50-90 km/30-55 mi. They are electrical, like lightning, and arise when the electrical field that occurs between the thunder cloud top and the ionosphere (ionized layer of the Earth's atmosphere) draws electrons upwards from the cloud. If the air is thin and this field is strong the electrons accelarate rapidly, transferring kinetic energy to molecules they collide with. The excited molecules then discharge this energy as a light flash.