Author Topic: Lightning and Tornado Activity  (Read 498 times)

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Offline ocala

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Lightning and Tornado Activity
« on: March 05, 2017, 10:43:34 AM »
Was reading about the Goes 16 this morning and the article said there is a lightning sensor on the satellite. What the article also said that I didn't know is that several minutes before a tornado touchdown there is a huge increase in lightning activity in the area of rotation. This sensor will up the warning time for a potential tornado.
As for lightning detection I always thought our ground based sensors covered the US almost completely.
Anyways here's a quote from the article about the sensor.
One of the key indicators of a strengthening severe thunderstorm on the cusp of producing a tornado is a significant increase in lightning activity several minutes before a tornado touches down. “Lightning trends often indicate storm intensity, so forecasters monitor lightning information to help identify strengthening or weakening storms,” says Dr. Rudlosky. “The GLM monitors lightning flash rates which often increase rapidly about 20 minutes prior to severe weather at the surface.  This information can alert forecasters to storms that are undergoing rapid transitions and may produce severe weather.” By combining the new GLM observations with existing observation systems like Doppler radar, forecasters may now be able to issue a tornado warning for an area based on the increased lightning activity detected in a storm cell, potentially giving those in the storm’s path crucial extra time to prepare and take shelter.
« Last Edit: March 05, 2017, 10:46:10 AM by ocala »

Offline Cutty Sark Sailor

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Re: Lightning and Tornado Activity
« Reply #1 on: March 05, 2017, 11:20:09 AM »
Back about 1976... I found out that a funnel showed a sharp increase in electrical activity, and somewhere I actually have the original plans and specs for a tornado detector.  The activity is NOT always in the form of "lightning', but emf pulses generated from the rotation.... they have significant predictable signatures, but I just do not remember the exact deal.  I think the Satellites are using similar, + visual, + data from a couple of other orbiting sensors
these figures below are incorrect, and I don't remember the exact research... if I stumble upon the stuff again I'll forward it...
Normally, these erratic pulses/pulse groups would be 'random', or
pulse groups less than 10pps or so within 5 seconds, less than 4 (5 second groups/minute) using one minute window.
If the cloud had rotation, other criteria, the pulse rate would increase to
Pulse trains >10pps occurring within 3 seconds, more than 12 (3 second groups/minute)  in a one minute window
As I say, those paradigms aren't accurate.. I just don't remember... but you get the idea.

The device used a small AM radio, off channel, audio out to simple counting circuits. (555 driven, I think)  It worked.
I sat on Skywarn mobile location several times and watched it trigger, saw a wall or rotation, and a couple of times a funnel. Lot of m home-made stuff and schematics etc got lost in the move in 2002...
It seems that that particular project might been derived have come from an article/project page in "Radio-Electronics" magazine.. I was heavy into such stuff during my career as an Electronics Tech.
Interesting thing.. the Blitzortung system, especially BLUE, lends itself well to this, and at least once a month, I wonder what happened to my long-lost project and data. I've got enough component inventory to build one up in an afternoon if I could locate the data. it was pretty simple, in a way.



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Offline WDoug

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Re: Lightning and Tornado Activity
« Reply #2 on: March 10, 2017, 06:48:01 AM »
When I lived in Nebraska, before NOAA Weather Radio and cell phones and before digital television, people use to tune their TVs to Channel 2 (providing there was no station on 2).
Normally, there would be just "snow" on the screen,  but if a tornado was close by, the screen would go pure white.   The theory was that the EMF in the storm would be detected and turn the screen white.   At that time,  the video signals were transmitted on AM.

Regarding the article in the electronics magazine,  I remember that.   I have built my own lightning detector using those old principles,  but updated it slightly using todays electronics.
I have an AM radio tuned to the low end of the broadcast band.   The lightning "crashes" are detected as static.   That voltage out of the radio's audio is fed into a IC chip that reads the voltage and then lights up a series of LEDs.   The stronger the storm, the more LEDs that light up.

Here's the link for the hand drawn schematic and the finished product.   Poor quality pictures, but you get the idea.