grateful deadconcert at night SPRITES are high-altitude luminous flashes that take place above thunderstorms in a part of the atmosphere called the mesosphere. Although sprites are usually rare, some storms can spawn them frequently. Typically the upper parts of clouds are charged positively and the lower parts negatively. Most often, it is the negative base of the cloud that flashes to the ground. But at times the upper, positive part can discharge directly to the earth, producing a lightning flash of exceptional intensity. About one out of 20 such positive cloud-to-ground lightning bolts are sufficiently energetic that they spawn sprites. These examples, recorded from the ground with a monochromatic video camera, have been colorized to match a color image obtained from an aircraft.

Image: Stephen B. Mende and R. L. Rairden; Colorization By Laurie Grace