Static dynamics

We call it “static” electricity, but it can sure cause havoc when it moves. My office carpet charges me up when I walk across it, and if I am dumb enough to touch a USB port on my computer it causes problems from disabling every USB device to shutting down the computer. “Whack”. If I’m thinking, I touch the cabinet first, to discharge the static harmlessly. The USB port is a vulnerable point in the system.

I was awoke in the middle of the night years ago during a snow storm, by the noise. “POP!….snick…..POP!….Snick…” with perfect regularity, over and over. That’s something that’ll get your attention in a deep sleep in the middle of the night. I had a 40 meter “inverted vee” dipole antenna atop my trailer, but it was a crude experimental set-up with no grounding switch. For equipment protection I simply unscrewed the antenna connector when not in use. Static was building up on the wire outside, then jumping to a metal desk lamp nearby– “POP!” A second later it jumped onto a ground cable next to the lamp– “Snick”. I guess it took a second for the charge to migrate to the pointy piece of the lamp where it discharged. It was dark, so I could see the sparks. They were impressive. Stupidly, I grabbed hold of the cable to screw it into a grounded jack I had set up. Yow! That’ll wake ya right up. It’s amazing how much voltage can be pulled out of a snow storm in just a few seconds.

When we were kids, we had to wait at the Spokane airport for a long time one day. We found that the carpet there would build up an impressive charge on you, and when you touched a doorknob or something you’d get a pretty good jolt. So naturally we played a trick on our little sister. We told her to touch her finger to someone else’s finger. “Ouch!”
“Try it with someone else.”
“Ouch!”
“There must be something wrong with you. Here; try it on me.”
“Ouch!” After several rounds of this we had her convinced that it was all her– Something was wrong with her, and after facing the prospect of a lifetime of never being able to touch another person without causing pain, she started crying. Then of course we had to console her and explain the joke, feeling guilty about it.

One winter night while driving home at night in sub freezing weather I watched a lightning storm. It was a little, single, isolated thunderhead off in the distance. Normally a thunder storm is driven by warm, humid air condensing as it rises, releasing its heat energy thus causing more rising and more condensation, etc. Vapor to liquid– There’s a lot of energy involved in changes of state, but in this particular case it was quite cold outside. Compared to the more familiar springtime or summer thunderstorms, this one was very low energy. One strike only every several minutes. Could this thunder storm have been the result of a liquid to sold change-of-state system? Never heard of such a thing. I’ve seen winter lightening only twice in my life, and the other time it was just one strike.

3 thoughts on “Static dynamics

  1. E.S.D. Electro Static Discharge. You can see voltages as high as 35kV depending on humidity. Out here on the Palouse where we have an average 20% relative humidity (at least that’s what I get in my house without my humidifier running), the higher values are much easier to obtain.

    Higher humidities (65-90%) though will drop that into the 1.5 kV range for the same source conditions. During extremely cold conditions humidity normally plummets. A couple months ago I drove home through a snow-thunderstorm. They’re definitely rare, mainly because the conditions to cause the static charge to build are a little more difficult to create. While more difficult, the charge can be larger if the conditions are met. This is because the lack of humidity makes the breakdown point higher.

    God, did I just remember most of that from memory. I guess I did remember something from getting my degree.

    • Yeah it can definitely mess you up. In my ham shack Mark II I used the proper LC filters which have capacitive coupling to the antenna and a constant bleed-to-ground through a choke, and discharge tubes in case of a nearby strike.

      A guy I know had a lightening rod grounded with a copper cable. It ended up with the copper cable vaporized after one storm– just el gondo, with little copper beads stuck in the paint on the side of the building.

      We once had a TV brought into the shop for repair after a lightning storm in Moscow, and the circuit board traces were mostly all gone. Complete havoc. Time for a new TV..

      Not static related, but my brother was installing an industrial power system in a granary here in Moscow years ago. He touched a large copper buss bar to the wrong place. He woke up on the floor with a burned face, like a really, really bad sunburn.

  2. We’ve had a very long winter this year in Minnesnowta, with snowfalls extending into just last week. We’ve had two severe storms last month that produced “thundersnow”, which is very unusual. The last time I saw lightning during a snowstorm was the Hallowe’en blizzard of 1991, when the storm dumped about 3 feet of snow on us. My experience (at least here) is that we only get thundersnow during storms that have very high moisture contents, and temperatures just below freezing. Those storms also tend to produce a LOT of snow.

    The houses here get very dry during the coldest months, and very few people used have humidifiers. When we were kids, we learned to unfold a paper-clip, and lick the tips of your fingers to get good conductivity between the clip and your hand. You’d shuffle your feet on the carpet, and then touch something metal to discharge it. We’d have contests to see who could throw the longest spark. It was kind of neat to do it in the dark.

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