Surprising photos of gigantic red shapes in the sky are regularly shared on social networks. The phenomenon of sprites is so extraordinary that some people find it hard to believe that it is real: these monstrous shapes, bright red, seem to have come straight out of a science fiction film.
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[EN VIDÉO] Discover the hidden side of storms The spectacular and mysterious sprites belong to the family of transient light phenomena (TLE).
Sprites are very real and even widespread, including in France. Most of the time they are not visible to the naked eye and appear later in photos. However, testimonies have described them for hundreds of years, particularly airplane pilots.
But these stories weren't taken seriously until 1989, when the first photo of sprites was accidentally taken during a rocket launch. The ones we also call Red Goblins, Goblins or Red Sylphs are reddish streaks that are very difficult to detect because they are very ephemeral: their lifespan is no more than a few milliseconds and sometimes up to a second – which is what it is in in this case allows you to see them in real time.
They are part of the “transient light phenomena,” which also includes another extraordinary phenomenon, the blue ray. They occur over the fiercest storms and appear when the strongest lightning strikes (the positive effects).
This is what we call the “domino effect”: the electrical charge from lightning beneath the storm cloud creates a second electrical charge above the cloud. They are formed at altitudes between 40 and 145 kilometers by the reaction of air molecules to the electricity (ionizing particles) emitted by the storm.
Why are they red when the flash is white or blue? It is the N2 dinitrogen present at this altitude that causes the red color. However, the underside of the sprites is often bluish. They can reach lengths of 50 to 100 kilometers or more, but their electrical discharge is weak compared to that of lightning.
They can take different forms: pillars or “carrots”, paths, fireworks, but the most spectacular form is that of jellyfish.
Photographing sprites requires luck, technique and patience
How can one successfully photograph them knowing that the phenomenon is very short-lived and there is no guarantee that it will occur in the event of a storm? THE Photographer Christophe Suarez is one of the few French people who managed to take a photo of it:
“Shooting red goblins is possible thanks to a combination of favorable elements. The prerequisite is the formation of cluster storms within a radius of 700 to 800 kilometers and a clear sky between the storm and the photographer. To capture the phenomenon photographically, specialists use very sensitive digital cameras and extremely fast lenses. They take thousands of images, which are then analyzed on a computer and look for a very faint red glow. A second method is becoming more and more widespread: the use of very sensitive cameras in video mode. In fact, an exposure at 25 frames/s takes 40 ms. The enthusiast produces spurts that can last several minutes. The video images are then extracted using a video editing program. Finally, the image is enhanced using photo development software.”
Most images of sprites come from the United States, but they are also widespread in Europe: “Sprites appear most of the time over strong organized storms such as MCS (mesoscale convective system). Such a situation occurs several times a year in France. Goblins can be photographed from more than 500 miles away, multiplying the number of possible situations. The south is the cheapest zone in France. Mediterranean storms last longer in autumn and the number of days with clear skies is greater.