What are some cloud-to-space forms of lightning that are not considered to be true lightning?
There are four types of electrical phenomena that have been observed that are not really lightning but still involve fascinating atmospheric displays. Called “transient luminous events” or TLE’s, they are usually seen during storms. They are sometimes called “cloud-to-space” lightning, though they do not actually originate within clouds. The first scientific paper on these phenomena was published in 1886, but scientists were not very interested in the subject until more recently, as photographic images became increasingly available.
Sprites: often reddish lights appearing above thunderstorms for very brief periods of time, sprites look kind of like jellyfish; they have a blob of light on top and numerous tendrils descending downward. Sprites can shoot 55 to 60 miles (about 90 to 95 kilometers) up into the atmosphere, reaching the ionosphere, and extend 100 miles (161 kilometers) across. They are very difficult to see, and for that reason were not reliably recorded until the 1980s.
Blue jets: blue lightning that emerges from the tops of thunderstorm clouds at speeds of about 62 miles (100 kilometers) per hour. Meteorologists still do not fully understand what causes blue jets.
Elves: a short name for a very long-winded description, elves are emissions of light and very low frequency (VLF) perturbations from electromagnetic pulse (EMP) sources. Appearing as giant rings that expand up to 200 miles (320 kilometers) in diameter, elves exist in the upper atmosphere at elevations of 55 to 60 miles (90 to 95 kilometers). Even more short-lived than sprites, they last about one one-thousandth of a second.
Tigers: first observed on January 20, 2003, this newest atmospheric light phenomenon has still not been adequately explained by scientists. Tiger stands for “Transient Ionospheric Glow Emission in Red,” and were first observed with the use of an infrared video camera over the Indian Ocean by Ilan Ramon, an Israeli astronaut aboard the space shuttle Columbia, which later exploded, killing the crew. The tigers that Ramon observed occurred as bright flashes when there was no thunderstorm activity nearby.