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Lecture: Ball Lightning: Narrator: Listen to part of a lecture in a meteorology class. Professor: When we talk about lightning, we usually think of lightning bolts, those dramatic zigzag classes that appear during a thunderstorm. This type of lightning, what we see most often, is cloud to ground lightning. But the type of lightning I want to talk about today, ball lightening. I doubt you come across it personally. Ball lightning occasionally formed right after a conventional lightning strike. It looks like a fuzzy growing fear of fireball. It can be as small as a pea or as big as a car. It can be white, blue, green or red. It can last for ten seconds or even longer. It may hover in the air or bounced a roll along the ground. It doesn't seem to follow air currents or the laws of gravity. Very strange, in fact, because some of the characteristics seem to defy the laws of physics. It's an objection scientific mystery. Another reason it's a mystery is that because ball lightning is such a rare phenomenon, scientists had to rely mostly on eyewitness reports. Nevertheless, at least a hundred theories about ball lightning has been proposed. The most popular one is that ball lightning is some kind of plasma, just like potatoes. Plasma is neither solid nor liquid, nor gas. It's a collection of charged particles taking the form of the gas light, cloud. So the idea is that a lightning strike as the energy source creates a plasma cloud made up of charged particles that grow. The main problem with this theory is that it fails to explain how the hot plasma can last for so long. Remember I said that ball lightning can last for ten seconds or longer after the initial lightning strike. Well, plasma normally decays within micro seconds of the energy source being discontinued. Another thing is that ball lightning usually stays close to the ground, which isn't how plasma would behave. A plasma ball would be really hot, much hotter than the surrounding air, and would rise very quickly, like a hot air balloon. Another theory claims that silicon is responsible for ball lightning. So the theory basically claims that ball lightning is the chemical reaction of silicon particles burning in the air. To test that theory, researchers tried to replicate the reaction in the lab. Eventually they were able to vaporize silicon, and as hypothesized, they got little balls of light that moves randomly around the lab by braiding, throwing off sparks. These artificially generated fireballs, and this point is important, these fireballs lasted eight seconds, which is almost as long as natural ball lightning reportedly last. Some researchers fault this particular explanation by pointing out that ball lightning has been observed when there was no silicon around. For example, in and around airplanes, ball lightning able to pass through walls and distancing, drifting down the aisles of airplanes in neat flight. Um, one answer to that objection is that if a chemical reaction is the mechanism, other materials besides silicon might also be able to produce ball lightning, materials like a rumor which you find in your planes, this hasn't been demonstrated yet. Tesearchers need better data in order to find out what ball lightning really is. There are thousands of eyewitness reports from around the world, but ball lightning hasn't been recorded systematically, because it's so unpredictable. To investigate conventional lightning, you can set up a video camera and scientific instruments when the weather report the thunderstorms and just wait. With ball lightning, you might be waiting indefinitely. In fact, some people even think it's an optical illusion. But given the lab results we've had so far, I think it's safe to say that's not what it is. Silicon is the most common element in the ground. It's the main component in sand. Now according to the silicon theory, when lightning strikes the ground, the silicon is turned into so hot vapor which moves up out of the ground and into the air. This silicon vapour condensers in the tiny silicon particles, which combine with the oxygen in the air and burn. The burning, that's the bowling ball we see.