What is red lightning?

3 min read

These red flashes can sometimes be seen shooting upwards into the top of the atmosphere. Here’s why they happen

WORDS ANDREW MAY

A photograph taken from the ISS showing a red sprite clearly visible on the right

Red lightning, also known as a ‘sprite’, is an intriguing weather phenomenon associated with very intense thunderstorms. While an ordinary lightning flash extends down from the clouds to the ground, a sprite shoots way up into the upper reaches of the atmosphere. But it only lasts for a millisecond or so, making it difficult to observe and study.

Given their elusive nature, ‘sprite’ is an appropriate name, although it actually stands for Stratospheric Perturbations Resulting from Intense Thunderstorm Electrification. Like regular lightning, it’s caused by a buildup of electrical charge in clouds, but in this case the excess charge is released into the ionosphere – around 50 miles up – rather than to the ground. Sprites are usually red in colour and can range in shape between a jellyfish and a carrot. Compared to an ordinary flash of lightning they can be huge in size, often as much as 30 miles across.

Although it looks striking when captured in a photograph, red lightning isn’t easy to observe from the ground for the obvious reason that it occurs far above the cloud layer. It can be seen more clearly from high-flying planes – including specially instrumented research aircraft – and it’s also been observed by astronauts on the International Space Station (ISS).

Red lightning isn’t the only upper-atmosphere phenomenon that can be triggered by thunderstorms. Collectively known as transient luminous events, or TLEs, other examples include blue jets, which are optical ejections from the core region of a thunderstorm, and ‘elves’ – Emission of Light and Very low-frequency perturbations due to Electromagnetic pulse Sources – which are rapidly expanding discshaped regions of luminosity.

SPRITES IN SPACE

A NASA illustration showing what a sprite might look like in Jupiter’s atmosphere

In common with many weather phenomena, red lightning could in principle occur on other planets that have an atmosphere, not just Earth. It’s been known, for example, that ordinary lightning is a common occurrence in Jupiter’s atmosphere ever since NASA’s Voyager 1 probe flew past the giant planet in 1979. In the case of sprites specifically, researchers at Tel Aviv University carried out an experiment in 2011 to test whether they could occur on Jupiter, its neighbouring gas giant Saturn and our own near neighbour Venus. They recreated the atmospheres of these planets in their laboratory and passed electrical discharges through them. They found that under the right conditions, sprites could form on all th

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How It Works Magazine

7 July 2022

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