It’s the middle of summer, the peak time for thunderstorms. This means it is also the peak time to find lightning’s stranger cousins – red sprites, blue jets, elves, trolls, and gnomes.
No, these brilliant lights are not fairy tales; they are a colorful community of lightning flashes that occur above thunderstorms.
Summer is the season for seeing red sprites. SOURCE: NASA
For over a century, these flashes of lightning that shot up from storm clouds, like stories of rains of toads, were dismissed as fiction. Even when respectable pilots or scientists (including CTR Wilson, a Nobel Prize winning physicist) described them, the scientific community ignored the events. Then, in 1989, something awkward happened. University of Minnesota scientists actually caught the so-called “sprites” on film.
Since then, scientists have been studying not just the lightning that crashes down from thunderstorms, but also the colorful flashes that stream up towards space. Electricity soars up to the electrically charged ionosphere, just as it plunges down towards the earth.
Different TLEs flash at different levels in the sky. SOURCE: Wikipedia
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Together, these events are labeled Transient Luminous Events or TLEs. Individual light flashes have much more playful names. The original lights were named sprites because they were mysterious, the other lights received fairy names because scientists can have a sense of humor.
So, if you look high in the sky, over the thunderstorms, what can you see?
Sprites—The most common TLE is a flash of red light directly above large thunderstorms. Sprites flash a fraction of a second after strong lightning strokes, soaring up almost 60 miles high. They are most frequently seen in the Midwest.
Blue Jets—A blue jet is a dim blue light that rises like a quick puff of smoke above heavy hailstorms. They are quite rare and usually can only be seen from airplanes.
Elves—Elves are brief disks of dim light that appear around 60 miles high in the atmosphere. Actually, the name is an abbreviation of the disk’s real name − Emissions of Light and Very low frequency from EMP Sources.
Trolls—These red spots pop near cloud tops after the flash of an extremely strong red sprite. Like Elves, Trolls are an abbreviation: Transient Red Optical Luminous Lineament.
Look over the top of thunderstorms to see sprites and other flashes. SOURCE: NASA
Gnomes—The tiniest and quickest flashes are gnomes. They are small white spikes of light that flash for a microsecond from the top of a large thundercloud’s anvil.
So next time you see a thunderstorm, look above it. You may see a fairyland.
Evelyn Browning Garriss, historical climatologist, blogger, writer for The Old Farmer's Almanac, and editor of The Browning Newsletter, has advised farmers, businesses, and investors worldwide on upcoming climate events and their economic and social impact for the past 21 years.