November 7, 2013
Lightning is silent, I think, because we say that it’s the thunder we hear (up to 12 or so miles away). But the two go hand in hand obviously. Lightning is becoming more silent due to the digital age. What that means is that our digital tv‘s don’t crackle with static and our radios are becoming more and more digital so it’s hard to tune in static or hear it anymore. Why is that? Our new technology is designed to interpret 1’s and 0’s so the various frequencies of sounds that would make the static in our old tv’s and radios…..is not detected in our new gadgets. Maybe lightning needs a digital upgrade.
Lightning occurs somewhere on this earth about 8 billion times a day. More lightning occurs when the weather is warmer so when it’s winter in the northern hemisphere our neighbors to the south get their share and the ones in the middle, they don’t get much of a break. We know where lightning is occurring practically instantaneously because we have satellites that detect subtle changes in the atmosphere. Even during the daytime these satellites apparently are good at detecting lightning 90% of the time including cloud to cloud and intracloud lightning.
I was reading a story about Ben Franklin and his debate with Royal Society members on whether his lightning rods were designed properly and if they did reduce the chance of lightning by defusing the atmosphere. It turns out that we can’t defuse the atmosphere and that long lightning rods are not necessarily better than short one foot ones. Gathering data about lightning strikes back then meant asking “respected” people what they might have witnessed. Even though the lightning rods we have now are very effective, interestingly, most typical houses don’t have lightning rods. They are found on more valuable structures. And many times these rods are hard to find because they can be blended into the structure.
What I really wanted to know about lightning though is how likely is a person in a swimming pool to be hurt by lightning. This would be a dangerous experiment because we’ve probably all read about someone being injured or dying from a lightning strike and we know that water conducts electricity. What I read from two different places on the internet is that a 20 foot distance would be needed and the other source said 200 feet. Since it’s easy to get out of the pool, that’s the best solution and getting out of indoor pools as well because plumbing could carry the electrical discharge into a pool. But apparently pools are unlikely to be hit by lightning since lightning likes taller structures. Still, easier to get out of pool than to depend on lightning hitting the lifeguard stand.
Most of us probably know about the method to calculate how far lightning is from us. Since sounds travels slower than light, it takes 4 – 5 seconds for thunder to travel a mile after you see the flash (flash to bang). The lifeguard association recommends swimmers exit the pool when lightning is 10 miles away. That’s maybe 40 seconds at the quickest to get out of the pool. I don’t recall being that cautious when I was a lifeguard. Better safe than sorry though, right? If you disagree with the lifeguard, find another pool to take your chances.
Here are a couple of interesting things about lightning. It’s thickness is less than a half dollar coin but the length can be 3 miles long and there’s an interesting type of lightning called red sprite lightning which can occur above the clouds. See the link below for some cool pictures of that.