Red sprites: Photographing a rare phenomenon
Rarely seen with the naked eye, red sprites are colourful bursts of energy in Earth’s upper atmosphere.
This incredibly rare weather phenomenon was recently documented by specialist weather photographer JJ Rao, in Derby in Western Australia’s Kimberley region.
What is a red sprite?
JJ explains, “sprites are massive, complex events caused by light emitted by atmospheric nitrogen that has been excited by an incredibly strong electric field, the kind of field generated by an unusually large, positively charged expansive cloud-to-ground lightning strike associated with a big thunderstorm.
“When a sizeable amount of charge is suddenly lost from the top of a storm cloud from such a strike, the new imbalance that occurs triggers a transfer of charge from the ionosphere, which, if strong enough, will cause a sprite.”
Image credits: JJ Rao/@nature.by.jj
How are red sprites photographed?
“Unfortunately, there is no silver bullet or general rule for photographing red sprites, as they are really unpredictable,” says JJ.
“It’s like chasing the yeti or some other mythical creature.”
JJ does, however, offer this advice:
1. You need the right kind of storm (large and powerful)
2. You need a low amount of cloud cover
3. You need a low amount of ambient light (away from cities)
4. You need the moon to play nice (around the new moon is best)
5. You need the right distance (too close, and the parent thunderstorm’s Anvil obscures anything, too far, and particles in the atmosphere turn everything into mush). Around 100km is generally ideal.
6. You need a lot more memory card storage space than you might think. You will be taking hundreds if not thousands of photos as there is no predicting if and when a sprite might happen. You don’t want to run out of space just as things start getting good.
7. You need to match your shutter speed to the conditions. Too long, and the frequent intracloud lightning will create a grey haze that drowns the sprite or blows out the image. Too short and you could lose a sprite in the gap between shots (a proven scientific fact). A sprite can be over and done in about 10 milliseconds; that’s about 20 times faster than the blink of an eye).
8. You need as wide an aperture as you can manage. Sprites are actually quite bright (about the same as Venus), but that brightness only lasts 10 milliseconds. You need to capture as much of the emitted light as you can.
9. Manage that ISO. While a higher ISO will result in a brighter sprite at first glance, the fine details in the tendrils and nodes can quickly get lost to the increased noise. A camera with good low light noise performance and ISO invariance helps greatly.
10. You need to have your focus spot on. Temperature changes throughout the night will cause the focus to drift. There is nothing worse than being out for hours, finding out that you successfully captured a magnificent sprite, hidden amongst thousands of images, then finding out on closer inspection that it is out of focus.
11. You need to be pointing in the right direction and at the right altitude. Seeing a sprite with the naked eye is difficult (but possible for these larger specimens). A large sprite, such as this one can reach up to 85km in altitude. There is a huge temptation to constantly check the camera to see if you were successful in capturing one. While this helps with refining your framing, you could easily lose valuable time that the camera is firing (think Point no. 7).
