There are more things between Heaven and Earth than we can possibly imagine. That is one of the most fundamental truths that mankind has discovered since it began to explore the world around it. It seems that every time we feel that we have figured out something, the universe throws humanity a curve ball that catches us completely off-guard. We find abundant life in the crushing cold depths of the world's oceans, rivers of liquid methane on other worlds, or animals that were long thought to be the product of myths and lore.
Many of these phenomena occur in the depths of the Pacific, or on other worlds altogether. It always has a special impact when one of these mysterious apparitions show itself in your own presence, or even in your region. Just a few days ago, one of these ghostly specters revealed itself over Ireland. An observatory in Armagh, Northern Ireland, was in the lucky position to record a sprite, one of the most mysterious phenomena in the upper atmosphere, beautiful and eerily haunting.
What is a sprite, you may ask. Quite frankly, that is the problem right there. Scientists don't really know what it is. They know how it looks, and how large a sprite gets, but the mechanism that triggers a sprite, as well as its internal workings are still largely a terra incognita for science. What we do know is that a sprite is apparently an electromagnetic phenomenon occurring in the upper atmosphere. They are in some way triggered by terrestrial thunderstorms, however the exact mechanism for triggering a sprite is, as I said, still unknown. Sprites are big, and I mean real big. They stretch between 50 and 90 kilometers above the Earth, and often cover as similar area. However, for something that large, they are extremely hard to find. They are tenuous and almost ethereal, as well as being very faint, making them almost impossible to see unless they are photographed against a really dark night sky.
 |
| Kinda spooky, eh? As the image caption states, this is the first color photo of a sprite, taken from an aircraft in 1994. |
Nevertheless, they are real, though that realization itself is only a product of the late 1980s, sprites first having been photographed on July 6, 1989. Since then, these ghostly apparitions have been photographed and filmed hundreds of times. Still, despite precise descriptions of how a sprite actually takes place, they are still a mystery. In fact, some of these observations make sprites appear even more mysterious than they already are.
 |
| Multiple Sprites over Kansas, observed in August 2002 |
Don't believe me? Well, how about this: Observation of sprites by high speed cameras taking up to 10000 frames per second have revealed that sprites are not solid flashes, like we are used to from "conventional" lightning during a thunderstorm. They are created by clusters of balls of ionized gas, between 10 and 100 meters in diameter. They usually appear at an altitude of 80 kilometers, and move downwards at up to 10% of the speed of light. They are followed mere milliseconds later by another cluster of ionized gas moving in the other direction. So basically, sprites are plasma projectiles, moving through the upper atmosphere at relativistic speeds. If that isn't strange, then I don't know what is. Equally strange is the fact that, while sprites are usually preceded by regular positive cloud-to-ground lightning, both the time and the location can vary widely. It is possible for a sprite to appear almost simultaneously with, and directly above a lightning strike, it is not at all unusual for it to appear up to 50 kilometers away, and up to 100 milliseconds later. That may seem like nothing to us, as far as lightning is concerned, it spans eons. That indicates that these sprites are triggered by another, as yet undetected phenomenon sparked (no pun intended? Yeah, right!) by lightning. As you can see, there is still a lot of research to be done to explain these weird phenomena.
 |
| Red Sprite, as observed from the International Space Station. Click on the image to enlarge it, the sprite is right above that bright flash of lightning in the upper right side of the image. |
But what about that thing recorded at the Armagh Observatory? What's so special about that? Well, first of all, you need very special conditions to record a sprite, due to their ethereal nature, as I stated above. You basically need to have a clear view of the sky above the respective thunderstorm, a dark sky, and preferably a camera that works fast enough to record these flashes. Remember, the whole thing is over in milliseconds. Oh, the thunderstorm needs to be intense enough to actually set off a sprite. So, while they may mathematically be a relatively common occurrence, catching one in the act is often another thing altogether. The Armagh Sprite, which was likely triggered by a thunderstorm in the counties just south of the border, Monaghan, or Dundalk, is one of only a handful that have been captured on film in the UK and Ireland. Basically, capturing a sprite this close to home is like having the unknown itself knocking on your apartment door.
Comments
Post a Comment