Most of us look downward for lightning: a bright branch reaches from cloud toward land, followed by thunder. But some storms also trigger an electrical display far above their cloud tops. For a few milliseconds, red tendrils appear high in the atmosphere, resembling a luminous jellyfish or an upside-down forest.
These events are called sprites. The playful name fits something so elusive that eyewitness reports long preceded convincing images. They are real physical phenomena, although a photograph can make their duration and visibility seem much greater than a person would experience.
The storm reaches beyond the clouds
Sprites belong to a family called transient luminous events: brief atmospheric glows associated with thunderstorm electrical activity. They form high above ordinary weather, often around 80 kilometers in altitude, after lightning changes the electric conditions below.
The reddish light is associated with nitrogen in Earth's upper atmosphere. Sprites can include diffuse bright regions and fine branching structures extending downward and upward. They are not solid objects, and their jellyfish-like appearance does not imply an animal-shaped cloud hovering over a storm.
Related phenomena have different forms. ELVES can appear as rapidly expanding luminous disks, while jets extend upward from storm regions. The family resemblance is electrical, but these names do not all describe the same event.
The bright cloud and the red structure occupy different layers
A storm photograph can compress enormous vertical distances into one frame. The ordinary cloud top and the sprite above it may appear to touch even when they occupy very different atmospheric regions. Before interpreting a picture, find the horizon and the storm's position. The dark gap between the weather and the upper display can be part of the important geometry.
The trigger and the glowing region need not be in the same place. A lightning discharge changes the electric conditions associated with the storm. The upper atmosphere can respond to that change. This is why “lightning above the cloud” is a useful first description but not a complete account of the connection.
The reddish light also belongs to a physical process, rather than to a red substance injected into the sky. Atmospheric molecules emit light after electrical excitation. Composition and density affect the response, which is one reason an Earth photograph cannot simply be recolored and treated as a measured image of a similar event on another planet.
Separate the sprite from the exposure that made it visible. A sensitive camera may record a faint structure that was difficult for an observer to see, and a selected frame can hold a millisecond event indefinitely. Neither fact makes the event unreal. Both affect how the image should be compared with an eyewitness's experience.
A discovery helped by looking sideways
In 1989, University of Minnesota researchers testing a low-light camera accidentally captured the first credible video evidence of sprites. That lucky recording helped launch a field of research into displays that are difficult to observe routinely.
Sprites are brief, and cloud cover can hide the view from below. Their association with storms does not mean the best vantage point is underneath one. A distant view over a storm can expose the clear sky above it. Images from aircraft and orbit have supplied additional perspectives.
NASA's Spritacular citizen-science project was developed to connect photographers' observations with researchers. Accurate times and locations help scientists compare an image with lightning records and other atmospheric information. An attractive photograph becomes more useful when its circumstances are recorded carefully.
Turn a photograph into an observation record
A useful sprite record needs more than a striking shape. Note the camera's location, the viewing direction and the exposure time. Preserve the time information as accurately as possible. Researchers can then compare the image with records of lightning in the relevant storm rather than associating it with whichever flash looked most dramatic from the photographer's position.
If a sequence exists, inspect the frames immediately before and after the apparent event. A single frame can obscure duration, and an artifact fixed relative to the camera may behave differently from a structure tied to the distant sky. Check whether the image shows a cloud-illuminating flash, a higher diffuse glow or a distinctly branching form. Identification rests on context as well as resemblance.
The linked Spritacular article explains why citizen observations can matter: many capable cameras are already watching storms, but scientific comparison benefits from consistent records. This is a project for observing from an appropriate distant vantage point or reviewing existing footage, not an invitation to stand underneath severe weather for a better picture.
The rewarding viewing question is therefore very specific: what happened above this storm, at this time, from this direction? That narrower question is more useful than assuming that every unusual red mark belongs to the same class of event.
Familiar air, unfamiliar questions
Scientists still investigate why sprites take particular shapes, how often they occur and how they interact with the broader atmosphere. Their connection to a lightning event is the beginning of an explanation, not the end of every question.
There are also hints of related events on other worlds. Juno observations at Jupiter were interpreted as evidence consistent with sprites or ELVES. A different atmospheric composition can change the expected color, reminding us that the same broad electrical process need not look identical everywhere.
Sources and further reading: NASA: Spritacular and the science of sprites · NASA: Sprites and ELVES, on Earth and at Jupiter
