Possible Very Rare Bipolar Negative-To-Positive CG Lightning Flash -- Slow Motion Lightning 7/21/24

#lightning #slowed #weather #science
Technical Summary:
This is a cloud-to-ground (CG) lightning flash which I believe is a bipolar CG flash where the first three strokes removed negative charge to ground, and the last (fourth) stroke removed positive charge. Downward bipolar CGs removing negative charge followed by positive charge are very rare. I believe this flash occurred at 01:58:20 UTC on July 22 and was located over Redstone Arsenal, or just SW of Huntsville, AL. NLDN detected four strokes (three negative, one positive), and initially I had thought that the detected positive stroke was a misclassified cloud pulse. Unfortunately, by the time I realized the significance of the flash, I no longer had access to its NLDN data. The stroke peak currents were high; about -130, -45, -20 kA (I don't remember the exact values) and the positive stroke I noted as +28 kA. This is, again, assuming that I'm analyzing the correct flash.
The video I captured is 500 frames per second; one video frame is two milliseconds. There is visible luminosity for 16 ms before the first leader is visually apparent: a downward leader with continuous branching characteristic of a negative leader. Positive leaders (identifiable by recoil leaders) are visible after the first return stroke. There is substantial in-cloud luminosity between the first and the second stroke that followed ~44 ms later. The second stroke formed a new path to ground, and leader morphology once again suggests a negative stroke. A third stroke came to ground in the first stroke's channel, and the brightening of the positive leaders in the frame after the return stroke suggests a third negative return stroke. The third stroke was followed by long continuing current and a bright M-component (current pulse during continuing current). About 60 ms later, there is intense in-cloud brightening that immediately cuts off the continuing current. This is indicative of dense positive charge being accessed by the flash, rerouting negative charge that has been flowing to ground. A fourth stroke to ground occurs 12-14 ms after the bright luminosity and followed the same path as the first and third strokes. Like the third stroke, the fourth stroke was followed by continuing current, which was shorter in duration, but evidently more luminous, than following the third stroke.
Without any other electric field or current data, or visible downward leader propagation that indicates leader polarity, the behavior of other visible branches can be used to determine stroke polarity. For example, the brightening of the positive leaders following the third stroke indicates that the return stroke was propagating towards the positive end, indicating a negative return stroke. Likewise, if visible leaders suddenly dim or decay following a return stroke, this suggests the polarity of the return stroke is the same sign as those leaders. This is why downward branches that don't connect to ground usually decay immediately after the return stroke. One has to be careful here, however, as strong negative strokes often cause the positive leaders to momentarily decay. This is likely what happened after the second stroke. The fourth stroke, however, appears to have caused a more sustained dimming of the positive leaders that recovered after the continuing current to ground ceased. The intensity of the continuing current, the observation that that the fourth stroke occurred during the same in-cloud brightening process that cut-off the negative continuing current after the third stroke, and the continuing current ceasing while the positive leaders are still highly luminous also suggest that the fourth stroke and continuing current removed positive charge.
The evidence is still not very robust, and it is still possible (though in my opinion unlikely) that the fourth stroke was a negative stroke that occurred immediately after the in-cloud positive charge region was exhausted. Electric field measurements would provide the most rigorous evidence, followed by data from LF lightning location systems with at least millisecond-scale temporal resolution. Data from the North Alabama Lightning Mapping Array would also be useful; this data would also indicate where in the cloud the flash initiated and in which direction the initial breakdown occurred, which in turn can be used to determine the cloud charge regions discharged by this flash.
MUSIC:
Blue Feather by Kevin MacLeod
Link: incompetech.fi...
License: creativecommons...

[@hugomalpeyre]

Thank you for all this poetry you captured. Thx for waking up early or going to bed very late, so others can learn and admire what you shot. And i love your choices of musics. Keep it up ❤❤❤

[@TwistedNatureChasing]

Awesome slow motion.

[@lydiak4524]

Truly stunning! Love it!

[@NikoStorm]

Great video!! 👍👍

[@ezequieldj]

I'm drooling

[@thelightninghunter23]

(Normally this is part of the Description, but I ran out of room!) EQUIPMENT I USE: Nikon D5300 DSLR Sony CyberShot RX100V www.sony.com/electronics/cameras YI 4K Action Camera Model YAS. 1616.INT www.yitechnology.com/ Samsung Galaxy S9 Smartphone Sony Stereo Digital Voice Recorder Model ICD-UX570 Video editing done using Shotcut Lightning information provided by Vaisala's National Lightning Detection Network (NLDN) through weather.us/lightning. The data is used for purely recreational purposes to roughly estimate stroke intensity and distance, the data presented here may be prone to error on my end and should not be considered to be an evaluation of the NLDN's performance. Thanks to Tom A. Warner and other lightning physicists and researchers who have helped me understand lightning processes explained in my videos. Tom has created a great resource for individuals interested in learning how lightning works. ztresearch.blog/education/

[@Night_Dweller1]

Hi

[@Night_Dweller1]

What is "M-Component"?

[@thelightninghunter23]

@@Night_Dweller1 It's a current spike that happens during continuing current of a ground flash. If you look at lightning in slow motion and there's a CG that just sits there after it hits the ground, you might see brighter pulses during that time. Those are m-components.