Scientists Capture Rare Photographs of Red Lightning (2024)

Jason Ahrns, a graduate student at the University of Alaska-Fairbanks, and other scientists from the U.S. Air Force Academy and Fort Lewis College—all part of a project sponsored by the National Science Foundation—have been on a mission. This summer, the group has taken to the skies in the National Center for Atmospheric Research’s Gulfstream V research aircraft, logging a total of 30 hours over multiple flights, in search of sprites.

Sprites, also known as red lightning, are electrical discharges that appear as bursts of red light above clouds during thunderstorms.Because the weather phenomenon is so fleeting (sprites flash for just milliseconds) and for the most part not visible from the ground, they are difficult to observe and even more difficult to photograph, rather like the mischievous air spirits of the fantasy realm that they’re named for. Ahrns and his colleagues, however, have captured extremely rare photographs of the red lightning, using DSLR cameras and high speed video cameras positioned in the plane’s window. The researchers hope to learn more about the physical and chemical processes that give rise to sprites and other forms of upper atmospheric lightning.

What’s it like to capture images of some of nature’s most short-lived and erratic features? I questioned Ahrns over email, and he explained what sprites are, why they occur, how scientists find them and why he’s so interested in the elusive phenomena.

First of all, what is a sprite?

A sprite is a kind of upper atmosphere electrical discharge associatedwith thunderstorms. A large electric field, generated by some lightningstrokes, ionizes the air high above the cloud, which then emits thelight we see in the pictures. They obviously beg comparison to theregular lightning bolts we see all the time, but I like to point outthat the sprites are much higher, with the tops reaching up to around100 kilometers, and higher. A lightning bolt might stretch around 10 kilometersfrom the cloud to the ground, but a sprite can reach 50 kilometers tall.

Under what conditions do they occur?

They’re associated with positive lightning strokes, which is when thecloud has a buildup of positive charge and releases a bolt of lightning.Negative strokes, from a buildup of negative charge, are about 10 timesmore common, so sprites aren’t strongly associated with the most commonkind of lightning, but it’s not really that uncommon either. More than just a positive stroke, the more charge that was moved during thestroke, the better the chances for a sprite. So we look for a largepositive charge-moment-change, which is basically the positive strokesweighted by how much charge was moved. Most large thunderstorms seem toproduce the conditions that lead to sprites, but some more than others.We just look for a storm with a history of lots of large positive charge-moment-change and go look at it.

What’s your scientific background? And how did you get interested insprites?

I’m primarily an aurora researcher, that’s what I’m doing my thesis onat UAF. I got involved in sprites because one of my graduate committeemembers is organizing these campaigns and needed some extra help. Ithought sprites were fascinating, and my advisor was supportive of mebranching out a bit, so I hopped aboard the team.

From what I understand, not much is known about red lightning,discovered just 25 years or so ago. With the NSF project, what are youand the other scientists hoping to learn? What are the biggest questionsyou have?

With this campaign we’re focusing on three questions. First, what basic physical and chemical processes are occurring? It’s still notclear what exactly is happening in a sprite, and why there are differentkinds of sprites, and what conditions give you a column sprite vs. acarrot sprite, for example.(All the sprite names just refer to their shape.) Next, do sprites have a large scale impact on the middle atmosphere?Sprites clearly represent some kind of transfer of energy, but is it ona scale that has a significant effect on the weather and climate? Wecan’t answer that without studying them. And, then, what can we learn about basic streamer physics? The tendrils comingoff the bottom of the sprites are ‘streamers’—little balls ofionization—moving about. Streamer speed and lifetime is related to air density, sostudying sprites in the very low density upper atmosphere is likelooking at streamers with a magnifying glass in slow motion,thoughthey’re still quite fast!

How many sprite-hunting missions have youbeen on?

Personally, this is my second aerial campaign. The first, in 2011, flewa total of 40 airborne hours, and this campaign did another 30 hours.It’s probably around 15ish total flights. The same crew, minus me, didone other aerial campaign in 2009.

What conditions, times of the day, areas of the country and altitudes are ideal for theseflights?

The midwest is productive, mostly because it gets these powerfulthunderstorms that last all night. Obviously, we need it to be dark, butother than that the time of night doesn’t seem to matter much, only howstrong the storm is and how much powerful positive lightning it’sproducing. We do notice that when the storm is going good it producesthe column sprites and carrot sprites, but as it dies off it seems toswitch over to less frequent, but bigger and brighter, jellyfishsprites. We fly as highas we can get, usually between 41,000 and 45,000 feet, but that’s simply toget a view over the clouds. We’re still below the sprites.

The lightning lasts just milliseconds, so I’m especially curious abouthow you photograph it. What equipment do you use?

For the still photographs, I just set my camera (a Nikon D7000 and a fastlens) facing out the window and set an intervalometer so the camera justconstantly snaps pictures. Then I go through later and delete everythingthat doesn’t have a sprite in it. It’s the same principle as lightningphotography; it seems like you’d have to get the timing just right butit’s really just statistical, if you snap a bunch of pictures one ofthem is going to get something sooner or later. I probably snap on theorder of 1,000 pictures for every sprite I come away with.

For the high speed video cameras, the camera has a buffer thatconstantly cycles through the previous however many frames of video, andwhen I see a sprite I hit a trigger that tells the camera to stop andsave whatever it just recorded. When we’re running at 10,000 frames persecond, the buffer fills up in about a second, so that’s how long I haveto recognize a sprite and hit the button. This can be pretty taxing on aslow night when you have to watch nothing happen for 45 minutes straightand still be ready with that less than one second reaction time.

Can you describe the setup? How do you actually take photographs fromthe plane window?

A picture is worth a thousand words, right?

And for the high speed video…

We have an internet connection aboard the plane so we can watch weatherconditions in real time. We just point the above cameras at the mostproductive looking part of the storm and wait for sprites.

How rare are photos like these that you have taken?

As far as I can tell, they’re pretty rare. There are some sprite imagestaken with meteor cameras and webcams out there, but they’re usually lowresolution due to being very far away and using a wide angle lens. I’veseen two or three sprite images taken with a DSLR, but they’re still from theground and a good distance away, and usually shots of something elsethat got lucky with a sprite in the background. I have the advantage ofbeing up in the air, close to the sprite producing region, with agood guess of where the sprites will appear, so I can use a lens with anarrower field of view to capture the sprite up close.

As for the images I got of blue jets, as far as I can tell they’reactually the first images of jets taken with a DSLR. That makes somesense, because the jets are a lot closer to the top of the clouds thansprites so much harder to see from the ground. Being in the air is amajor advantage.

What do you find artful about the images, if anything?

I think there’s a really otherwordly starkness about them. Take this one (above), forexample.You’ve gotthis nice serene starfield, and some cool, calming blue light coming upfrom the lightning below. Then BLAM! This weird, menacing, totally alienlooking sprite just takes over the whole scene, like ‘I’m here, what areyou gonna do about it?’

Hans Nielsen, the principal investigator on the campaign (and mypreviously mentioned committee member), says this one (below) reminds him of theclassic Dutch paintings, with its sepia tones and slight blurring fromthe atmospheric haze.

What have you learned thus far about sprites by participating in thisproject?

Personally? When I joined the 2011 campaign I knew nothing about spritesbeyond the Wikipedia entry. I learn more every night of the campaigns,listening to the others talk about conditions beforehand, what we’reseeing during the flights and our ‘what we did right, what we didwrong’ discussions over post-flight beer. I’m still a newbie compared tothe other guys, but I’m now at the point where I can field most generalpublic questions about sprites and sprite hunting.

Where and when are you flying next?

Nothing is set in stone, but we’d really like to fly again next summer.Hopefully we can make that happen.