Lightning Strikes

I was on vacation with my family last week and did not quite manage to get this entry up on time and so missed last week. But I enjoyed the time spent with my family, visiting and traveling to new places.

There have been a lot of fires in CO this year. The dry winter, dry spring and very hot, dry and windy summer weather have made for perfect conditions for fires to spread rapidly in the forested areas of the mountains. Because of this, there is an extreme fire ban in CO to prevent more fires. This was the quietest 4th of July I can remember because many of the towns around where I live cancelled the fireworks celebrations. No one wanted to start another fire.

Unfortunately, mother nature has not been informed of the fire ban. Many of the fires this year were started by lightning strikes during one of our many dry thunderstorms – lots of lightning and thunder and little or no rain.

A few weeks ago, I went out for a walk with my daughter and looked up to see a huge plume of smoke in the sky. I immediately looked up the news to try to figure out where the fire was – not close enough to be a danger to us (other than the horrible smoke) but close enough to affect many of my friends. In the news article, it stated that the fire was probably started by lightning as 51 lightning strikes had been detected in the area.

51? Really? The curious geek in me forgot all about the fire and started to wonder how they could possible know that. I spent some time looking into lightning detectors. There are several different types, but this article mentioned ground detectors, so I wanted to know how those work.

Lightning is really cool, and of course, a little scary too. But I have always been mesmerized by watching lightning flashes on a stormy day. In order to understand how ground detectors measure lightning, let’s first think about why we can see lightning – what is causing that huge bright flash?

Lightning is caused by huge static discharges. In an electrical storm, there is a huge charge difference between the clouds and the ground. This sets up a very large electric field across the air. This basically means that there is a huge amount of energy stored that has the potential to affect the air around it.

If the charge stored is enough, the electric field starts to ionize the air around it. This means that the strong electric field can actually tear electrons off of the atoms in the air. These electrons then become free to move around (no longer tightly attached to the atoms) and this causes a current to flow through the air like it would through a metal wire. (How Stuff Works: Lightning).

Very cool! And sort of scary…something powerful enough to rip atoms apart certainly is going to do a lot of damage if it hits me!

As this energy moves through the air, this electrical energy and atom ionization emits electromagnetic radiation – light. So we see a bright flash of light. You can see a pretty picture of the lighting and its spectrum (what colors are contained in this white light) here.

The lightning also emits a characteristic lower frequency electromagnetic radiation. In order to detect the lightning, antennas are set up to detect this lower frequency radiation. For cloud-to-ground detection, a set of three antennas are set up to triangulate the signal. All three antennas will detect the signal from the lightning and by measuring the time it takes to reach each antenna, the location of the lightning strike can be determined. Visible light detection (the big bright flash!) is also used to make sure that the lower frequency radiation is really coming from lightning and not some other source. (Wikipedia)

I never knew that these types of detectors were set up around us. I think it’s really cool that lightning detectors work so well. You can even make your own basic lightning detector if you like home electronics projects.

Despite the high level of technology and engineering that goes into really effective lightning detectors, I must admit that I am still more in awe of the amazing photographers out there that can take beautiful pictures like this (Wikipedia Commons):

During our vacation, we landed twice very near a thunderstorm. Despite being quite exhausted from travel and delays with an infant, I was in awe of the beauty and power of the lightning viewed from the sky. It is an amazing thing.

Fortunately, the weather has improved since the worst of the fires in CO. While it is still dry here, daily thunderstorms have brought some rain to help things from getting too dry. Of course, these storms also tend to bring lightning. Hopefully the wetter conditions will prevent more fires, but it is still important to be careful in the late afternoons, especially in the mountains. Lightning is beautiful but also quite powerful and dangerous.

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