Sprites, the luminous red glows that are the high-altitude companions of some lightning strikes, are the focus of a new study by researchers Steven Reising of the University of Massachusetts, and Umran Inan and Timothy Bell of Stanford University in California. Sprites accompany roughly one in every 200 lightning strikes. They tower up to 55 miles above a thundercloud, occurring simultaneously with a lightning strike, and can be seen with the naked eye, sometimes from as far away as 400 miles.
Sprites are electrical phenomena that appear above thunderclouds, reaching the lower ionosphere.
These striated, glowing ribbons appear at several-minute intervals. They are found above all the major landmasses of the earth, according to Reising. The importance of the new finding is that the radio signals produced by lightning discharges that lead to sprites are distinctly different from those due to other lightning discharges. The team recorded the radio signals emitted by each lightning strike. For each visible sprite, they examined the corresponding radio wave measurements using custom-designed radio antennas and receivers.