• After witnessing the continued decrease of involvement in the SpotterNetwork staff in serving SN members with troubleshooting issues recently, I have unilaterally decided to terminate the relationship between SpotterNetwork's support and Stormtrack. I have witnessed multiple users unable to receive support weeks after initiating help threads on the forum. I find this lack of response from SpotterNetwork officials disappointing and a failure to hold up their end of the agreement that was made years ago, before I took over management of this site. In my opinion, having Stormtrack users sit and wait for so long to receive help on SpotterNetwork issues on the Stormtrack forums reflects poorly not only on SpotterNetwork, but on Stormtrack and (by association) me as well. Since the issue has not been satisfactorily addressed, I no longer wish for the Stormtrack forum to be associated with SpotterNetwork.

    I apologize to those who continue to have issues with the service and continue to see their issues left unaddressed. Please understand that the connection between ST and SN was put in place long before I had any say over it. But now that I am the "captain of this ship," it is within my right (nay, duty) to make adjustments as I see necessary. Ending this relationship is such an adjustment.

    For those who continue to need help, I recommend navigating a web browswer to SpotterNetwork's About page, and seeking the individuals listed on that page for all further inquiries about SpotterNetwork.

    From this moment forward, the SpotterNetwork sub-forum has been hidden/deleted and there will be no assurance that any SpotterNetwork issues brought up in any of Stormtrack's other sub-forums will be addressed. Do not rely on Stormtrack for help with SpotterNetwork issues.

    Sincerely, Jeff D.

Upward-moving lightning questions

  • Thread starter Thread starter Dan Robinson
  • Start date Start date

Dan Robinson

ok-52901c.jpg


A few questions I thought I'd toss out to the forum regarding upward-moving lightning. I cross-posted this to the Lightning list but I'd be interested to hear discussion from Stormtrack members.

1.) Has upward-moving or 'ground-to-cloud' lightning ever been observed or documented occuring apart from man-made structures (towers, skyscrapers)? That is, is it safe to say that this type of lightning exists today largely as a result of man-made objects? I'm sure it probably *does* occur naturally in rare instances, but I have never personally observed or seen a photo of upward-moving lightning coming up from the earth itself (or a tree, mountain peak, etc).

2.) In a question closely related to #1, is there a known 'threshold height' for antennas/buildings to initiate upward-moving lightning? I'm estimating, based on observation, that towers need to be over 800 to 1000 feet (~300m) high (AGL) to be truly prolific initiators of upward discharges. The higher the tower rises above this mark, the more strokes will be initiated during an average storm. Of course, this might also depend on storm-specific conditions of cells passing over the tower.

3.) Dr. Orville offered the explanation a few months ago (on the Lightning List) about positive CG lightning being unbranched due to converging electrons at the leader front. Example:

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I have observed and photographed both branched and unbranched upward-moving strokes from towers - does this same converging/diverging principle apply to upward-moving lightning strokes initiated from ground-based points? That is, can it be assumed that a highly branched upward-moving channel is negative and an unbranched one is positive (basically a CG in reverse)?

To throw an even more complex twist to question #3 - many of us have seen the video of the jet airliner in Japan getting struck by lightning.

http://www.quartzcity.net/~chris/blogpicts...tningstrike.jpg

In the video, the plane clearly initiated both upward and downward leaders simultaneously, and both were branched.

4.) How does leader branching differ between upward and downward ground strokes? They are visually different - downward stepped leader branches terminate in mid-air, yet upward branching seems to universally continue up into the cloud to find a 'connection', none terminate in mid-air (as in the Japanese plane photo above)
 
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