Elves and Sprites
Upper atmospheric lightning or upper atmospheric discharge are terms sometimes used by researchers to refer to a family of electrical breakdown phenomena that occur well above the altitudes of normal lightning. The preferred current usage is transient luminous events (TLEs) to refer to the various types of electrical discharge phenomena in the upper atmosphere, because they lack several characteristics of the more familiar lower atmospheric lightning. TLEs include red sprites, sprite halos, blue jets, gigantic jets, and elves.
At first the terms elves and sprites implies a certain almost mythic note. They are an electrical discharge associated with thunderstorms but normally above them as opposed to what most people see from underneath a thunderstorm. They are best observed from beyond the earth.
Elves often appear as a dim, flattened, expanding glow around 250 miles in diameter that lasts for typically one millisecond. They occur in the ionosphere 60 miles above the ground over thunderstorms. Elves is an acronym for Emissions of Light and Very Low Frequency Perturbations from Electromagnetic Pulse Sources.
Sprites are large scale electrical discharges which occur high above a thunderstorm cloud, giving rise to a varied range of visual shapes. The phenomena were named after the mischievous sprite (air spirit) Puck in William Shakespeare's A Midsummer Night's Dream. They normally are colored reddish orange or greenish blue, with hanging tendrils below. They often occur in clusters above the Earth's surface. Sprites have sometimes been held responsible for otherwise unexplained accidents involving high altitude aircraft flying above thunderstorms.
A team of Spanish researchers has made a recent high speed recording of elves and sprites in storms, fleeting and luminous electric phenomena produced in the upper layers of the atmosphere. Their analysis of these observations has been published in the Journal of Geophysical Research.
The results show there are many fewer elves in storms that form over land than those at sea, apparently due to winter storms having greater energy. The scientists also observed the interaction between two sprites. A branch of one of them hit and bounced off the second, giving clues about their dynamics and electric structure.
These elves and sprites are illustrative of the many phenomena that are not clearly known because of their relative rarity and briefness.
For further information: http://www.sciencedaily.com/releases/2010/06/100610093511.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily+%28ScienceDaily%3A+Latest+Science+News%29&utm_content=Google+Reader or http://en.wikipedia.org/wiki/Upper-atmospheric_lightning