Red sprites
Lightnings are phenomena that we all are used to seeing during thunderstorms. However, the white and
light blue strikes are not the complete picture. Second type of a lightning phenomena occurs above the clouds. Directly above the cloud-to-ground or cloud-to-cloud lightning stikes, appear weak but massive flashes. The mostly red illuminations apear from the tops of the clouds up to 95 km above. Red sprites are very difficult to spot with an naked eye. Since the sprites occur above the active thunderstorm, to spot them one has to able to see above the clouds (for example when a thunderstorm occurs on the horizon).
Blue jets
Blue jets, similarly to red sprites, are observed above the active thunderstorm. They appear as blue illuminations from the core of the lightnings rich region of the thunderstorm. Blue jets disappear about 40-50 km above the clouds. The blue color is assumed to come from nitrogen emission caused by high energy collisions with oxygen. Together with red sprites, blue jets have been reported first time in 1989.
See also:
weird weather phenomena - part 1