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Different Forms Of Lightning

After taking a little break from our look at severe summer weather I figured it was time to pick up where we left off back in early May. In our last article on severe summer weather we took a technical look at lightning and I ended that article by letting you know we would take a look at the different types of lightning – so here we go!

Nearly all lightning you see is the classical lightning that you would draw if someone asked you to draw a picture of lightning. This lightning is known asfork lightningor plain old regular lightning. Looking closer at this type of lightning it can be broken down into several different categories.

The first of these iscloud to groundlightning. This form of fork lightning has the lightning bolt originating in the cloud and it moves through the air toward the ground. The next category iscloud to cloudlightning. Here the fork lightning originates in one area of cloud and then travels horizontally to another area of cloud. With the cloud to ground lightning we can usually see it as fork lightning and with the cloud to cloud lightning we can sometimes see it as fork lightning, but often this form of lightning is partially blocked by the clouds. In this case we don’t see the actual fork of lightning, but instead we see the light coming off the fork lightning reflecting off of the clouds. When this occurs we call it sheet lightning.

Fork lightning and sheet lightning make up pretty much all the lightning we experience, but there are other rare forms of lightning, a couple of which have only been photographed, videoed and identified over the last 20 or so years.

The first and probably most heard of form of rare lightning isball lightning.While this form has been reported several times over the last several hundred years, I have yet to hear or see of any video or picture of this type of lightning. Ball lightning is reported to be a slow-moving ball of lightning that can travel in an erratic pattern or simply horizontally. Some reports have the ball of lightning making no noise while other reports have stated that the ball hissed as it moved along. I think the really unusual aspect to this type of lightning is how long it can last, with reports indicating that it took several seconds,

up to tens of seconds, from the time it was spotted to the time it disappeared. How it disappears is also interesting, with reports ranging from it simply disappearing with no noise, to “pops” and small explosions as it dissipates.

OUT OF THE BLUE

Another rare form of lightning is an unusual form of regular old fork lightning. Ever heard the termbolt out of the blue?Well, this term has its roots in a form of fork lightning that literally occurs right out of a clear blue sky. No, this is not some bizarre type of lightning that occurs without clouds around. This type of lightning is a very long form of regular fork lightning. Often, once a thunderstorm has passed by, it clears up right away. The thunderstorm may have moved off far enough that you can’t really hear the thunder, but that storm can still produce lightning and some of that lightning can travel upwards of 20 kilometres from the base of the storm. So you can be out in the sun with the storm seemingly long gone, then boom,there can be a flash of lightning right out of the clear blue sky.

Another unusual form of lightning also seems to happen without any clouds present and this isheat lightning. This type of lightning is usually seen during heat waves, hence the name. No matter what people tell you, this type of lightning is coming from a thunderstorm. The storm may not be producing rain, but it is still a thunderstorm. When people report seeing heat lightning they are actually seeing the reflection of lightning that is occurring in a thunderstorm quite far away – so far that often you can’t even make out the clouds because they are “washed out” in the haze associated with the heat wave.

Our final two types of rare lightning are relatively new to the lightning scene, and as more and more research is done on these two types of lightning we are starting to realize it is not as rare as we first thought. These two types of lightning are known asspritesandjets.They occur where we never thought lighting could occur, and they dwarf all the types of lightning we have looked at so far. Both of these types of lightning occur above thunderstorms, so to see them you have to be looking at a thunderstorm off in the distance. Sprites are a form of lightning that appears at the top of a thunderstorm moving outward. They are very large, with estimates putting their size at the equivalent of Mount Everest. Jets also occur above thunderstorms and can travel upwards of 50 km.

I’m pretty much out of room for this week; if you would like to know more about these unique forms of lightning try looking up “mega lightning” on the Internet.

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Whenpeoplereportseeingheatlightning they’reactuallyseeingthereflectionoflightning occurringinathunderstormquitefaraway.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.

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