Tuesday, August 6, 2013

Sprites 2013: Update #5

We flew again tonight, but kind of got burned by the storm. There was a large number of positive charge-moment-change around 8:00 when we were planning, and just the lightning map in general looked like an unusually high number of positive strokes. Normally we see about 1 positive stroke out of every 10 or so, but tonight it seemed like it was around 50/50. And that was reflected among separate storms across the US, making you think there must be something larger controlling the fraction of positive strokes. It's interesting.

Anyway, we took off around 9:00pm, based on the fact that there was a very cold storm with lots of positive CMC, which is exactly what we look for. But it just died almost as soon as we were in the air. There was still a lot of lightning, but the big positive CMCs almost disappeared. I don't know what happened, and I actually don't think anyone knows enough about what sets the fraction of positive lightning strokes to really explain what happened. We had a long discussion about this over post-flight beer - someone should really figure this out.

But long story short, we only recorded two sprites to high speed tonight, neither of which was very good. One we only got the upper halo part of (which is pretty useless as spectra goes), and the other saturated the intensifier, so we can't use its spectrum either. We called the flight early, and now have about 10 flight hours left. Enough for two 5-hour flights, or, if our next flight is good, we'll just stay in the air as long as we can and call that the end.

On the plus side, I got another sprite in my dSLR. This whole time I've wanted to use a tripod to place my camera in a window and just let it shoot, but the NCAR folks are pretty strict about stuff like that. Well everyone was interested enough in my shots from last time that I was able to ride the good spirits into putting my camera into the window with a gorilla pod, using my bandanna as a dark cloth. Looks like this:

20130805_211905

The first of the two sprites tonight was too far forward to catch in the Nikon, but I did manage to catch the second one:

Sprite Image

And, since we caught it on high speed as well, here's the same sprite at 10,000 frames per second, slowed down by about 666x:



So that's pretty cool. Since we still have 1 or maybe 2 flights left in this campaign, I'm still hoping to capture something that puts this to shame :P but if this is the best I get, it's still pretty damn good. And, the PI's are so impressed that they want me to put some real effort into this on the next campaign. It's a great public outreach opportunity, as demonstrated by the fact that my Flickr page got more than 10,000 views on the day I put the first pictures up. So if I don't get the shot to end all shots this campaign, I'll be well ready for it next time...

Edit: Oh yeah! In the sprite excitement I almost forgot we had some quite nice evening light while fueling the aircraft and waiting for dark:

Fueling

DSC_5783

DSC_5737

32 comments:

  1. First high-speed sprite I've seen. Awesome! Lucky for you, and a treat for us. Congratulations!

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  2. Hi Guys. I'm operating a meteor radar scatter system in OKC AND a Sandia Sentinel Camera. The meteor scatter also catches reflections from lightning events between me and the radar emitter in Kickapoo - including events directly overhead us. I have screenshots 24/7 of the radar events. Given known UTC times I can extract these. I'm sure the data was collecting during your observation sorties. Some may coincide with yours and might be good data for your analysis. My email is falcon99@sbcglobal.net.

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  3. For what it is worth we had this one nailed down to the specific bolt creating it. http://www.extremeinstability.com/2013-5-31.htm

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  6. How does one get on to one of these flights?

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    1. Years of study :P

      I got to know the researchers running it and convinced them I'd be useful. There was a fair amount of luck involved. Of course, if you have the money to charter a jet there's nothing stopping you from flying your own campaign. I certainly couldn't afford it, so I'll stick with the research flight.

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    2. Well you're definately proving your usefulness! Keep up the great work. I live in the Detroit area. We have a lake (Lake St Clair) to our east which is approx. 30 miles accross to our east. Would this be an ideal location to sit on the west shore and see the top of an east-moving thunderstorm? How far away to they have to be from you? When we were little, we used to watch the storms that had just hit us proceed out over Canada for their cloud to ground strikes about 25 miles away. Sounds like we'd have to wait a little longer...?

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  7. Excellent work Jason....Too bad your flight time is limited. If you want to see something truly spectacular you should fly over some the thunderstorms here in Puerto Rico in the month of September. I've photographed and witnessed two Gigantic Jets out here and they were awesome. Too bad my camera has limited settings because the photos don't do them justice. For those of you that haven't seen one yet this is how I could best describe it. First you'll see a large bolt rising from the top of the storm cloud and then it quickly collapses but then it instantly rises again but this time it ejects billions of blue luminous beads that turn red as it travels higher into the atmosphere. Its like watching a fireworks display.... only this one is 10 times better because it was produced by Nature.

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    1. We've talked about flying over your area! Unfortunately we're just too limited on flight time. I would love to see a gigantic jet.

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    3. If you can get funded by the NFS to do your research from the Arecibo Observatory it could be cheaper than flying above the storms. Pasko did it back in 2003.

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    4. Frankie,
      How far was this (Gigantic) jet-producing cell from you?

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    5. ...assuming you were on the ground...

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    6. One was approx 30 miles and the other was probably about 80 miles. Not really sure,just guessing. Here are the links: https://www.youtube.com/watch?v=p8EEyJ-m5qQ https://www.youtube.com/watch?v=gk9ju2WUY5Q

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  8. Hi Jason,

    About the source of the unusual number of positive strikes...
    Has anyone considered the total positive charge of the inner van Allen belt?
    When i make a rough estimate of its total charge it is an order of magnitude bigger than the 500.000 C of the ionosphere.

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    1. I don't know that anyone has looked into that. I am not a meteorologist, but as far as I can tell what leads to a given ratio of positive to negative lightning is pretty much unexplored territory.

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    2. Well I am pretty sure that meteorologists dont go much higher than the stratosphere and are more into thermodynamics than into electrodynamics.
      The problem is that electrodynamicists ( that is not a word - it has squibles under it, sorry ) treat the problem of atmospheric electricity as a problem for meteorologists and are not aware of the contribution they could make by considering their data. Hans Volland does as much in his epic book about atmospheric electrodynamics.( Springer 1984).

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  9. Slowed down and seen frame by frame it looks as if moisture, maybe trapped with our hydrocarbons, is interacting with the huge amounts of solar wind our beautiful suns been throwing our way.

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  10. Just wondering what setting you use on the Nikon

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    1. f/1.8, ISO 6400, 3/4 second exposure.

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  11. The sprites you capture are stunning!! Do you ever use filters to capture sprite properties at various wavelengths?

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    1. We're using a diffraction grating in front of one of the high speed cameras to do that

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  13. If I may be so bold, explaining the color change of the red topped sprites with purple bottoms seems kind of easy. The charge at the top appears more dense and the red color more intense than in the lower portion, and with the blue sky filtering through from behind, you get purple. No?

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    1. Good idea, but you can still see the blueish bottoms in pictures that don't have the blue lightning light behind, like these two:

      http://www.flickr.com/photos/musubk/9426348239/
      http://www.flickr.com/photos/musubk/9448221189/

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  14. Awesome detail Jason. Hopefully one day you'll capture a gigantic jet also. I was told that the transition from blue to red in my gigantic jet was caused by the charged particles interacting with the chemical composition of the layer it was traveling thru in the upper atmosphere. In the lower part of the upper atmosphere you will get blue and as you travel further up it will transition to red. They compared it to the auroras which give us different colors also. If you mix blue with red you get purple so that might explain the purple below your sprite.

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  15. I wonder if maybe the color might also be determined by the strength or amount of charge in these charged particles. Just guessing....I'm not a physicist.

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  16. Thank you for these photos and high speed videos. Fantastic detail in the photo with a hand full on the left hand side. They almost look like SciFi-ish red 'sky plants' with purple roots. A very SciFi look to the photo. The high speed videos seem to me to show a progression from the top to the bottom which suddenly changes at the point between the red and purple from a smooth straight line flow to an almost explosive branching which forms the 'roots'. Beautiful. Thanks again!

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  17. Remarkable. It's lovely to know there's a community of humans so focused and fascinated by wonders, and spreading the word. Thanks for expanding my horizons. There's an atmospheric delight I've looked at on a site called Scribblygum (I think it's still up) and a cloud formation that you can ride that rolls into Australia between August and November called The Morning Glory, noted by the Aborigines before the hang gliders and pilots. I am very fond of all weather pheonomenon. Thanks for your fascinating study.

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  18. Frist of all, what is your name?!? I can't find it anywhere. Second I was watching NOVA last night (11/20/13) on our local PBS channel (Detroit, MI). I believe they were filming your flights. They showed two mid-size jets taking off with science crews and cameras from somewhere in Colorado running up and down the high plains next to big t-storms. The highlight was the high-speed camera close-ups of sprites, halos, elves, etc. Was that you?

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    1. Name is Jason Ahrns. I don't think it's anywhere on the blog, but it is elsewhere on the net associated with this screen name.

      Yeah, the PBS special was me! It was a previous campaign we did in 2011, not this most recent one. The Japanese TV station NHK filmed it as part of a three hour special; one hour on sprites, one hour on auroras, and one hour on meteors. It looks like the English version compressed the whole thing down to one hour and dropped meteors altogether. I didn't even know it was coming out, the first I heard about it was yesterday when someone sent me a 'you're on TV' message.

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