<div>2b-unit10 There is thunder 拓展 part2<br></div>今日主題----閃電。有了昨天靜電部分的鋪墊，了解到身邊的靜電想象，那么移植到天空中云朵帶電，理解起來就容易一些。<div><br><div><b>1. What is lightning?</b><br>Lightning is a bright flash of electricity produced by a thunderstorm. All thunderstorms produce lightning and are very dangerous. If you hear the sound of thunder, then you are in danger from lightning. Lightning kills and injures more people each year than hurricanes or tornadoes; between 75 to 100 people.<br></div></div> <b>2. What causes lightning?</b><br><ul><li>Lightning is an electric current. 閃電是電流。</li><li>Within a thundercloud way up in the sky, many small bits of ice (frozen raindrops) bump into each other as they move around in the air. All of those collisions create an electric charge. After a while, the whole cloud fills up with electrical charges. The positive charges or protons form at the top of the cloud and the negative charges or electrons form at the bottom of the cloud.在空中的雷云中，許多小塊冰（凍雨滴）在空中移動(dòng)時(shí)會(huì)相互碰撞。所有這些碰撞都會(huì)產(chǎn)生電荷。 一段時(shí)間后，整個(gè)云充滿了電荷。 正電荷或質(zhì)子形成在云層的頂部，負(fù)電荷或電子形成在云層的底部。</li><li> Since opposites attract, that causes a positive charge to build up on the ground beneath the cloud. The grounds electrical charge concentrates around anything that sticks up, such as mountains, people, or single trees. The charge coming up from these points eventually connects with a charge reaching down from the clouds and - zap - lightning strikes!由于相反的事物吸引，因此會(huì)在云層下方的地面上積聚正電荷。地面上的電荷集中在粘附的任何物體上，例如山脈，人或單樹。 從這些點(diǎn)上來的電荷最終與從云層上下來的電荷相連，并且-擊打-雷擊！ </li></ul> Have you ever rubbed your feet across carpet and then touched a metal door handle? If so, then you know that you can get shocked! Lightning works in the same way. <b>3. Types of lightning and types of lighting strikes</b> There are three primary types of lightning:<br><b>Intracloud (IC)</b><br>? Occurs within a single thundercloud<br>? In intracloud lightning, the reaction occurs between areas of differing electrical potential<br>? Most frequently occurring type of lightning<br>? Commonly occurs between the upper and lower levels of a thunderstorm<br><b>Cloud to Cloud (CC)</b><br>? Starts and ends between two different thunderclouds<br>? Another term for cloud-to-cloud lightning is 'Anvil Crawler' for its scrambling motion through cloud layers of a thunderstorm<br>? This can also be referred to as 'Spider lightning'<br>? Usually seen as a thunderstorm, passes over the observer or when the storm is settling down<br><b>Cloud to ground (CG)</b><br>? Begins in a thundercloud and ends on the ground<br>? Least common type of lightning<br>? Best understood type of lightning<br>? Easily measurable by instruments due to it ending on a physical object (Earth)<br>? Poses the greatest threat to life and property since it strikes the Earth<br>? Can be positive or negative (positive is more dangerous)<div><b><br></b></div><div><b>Ball lightning 球形閃電</b><br></div> Ball lightning is a glowing ball of lightning that sometimes appears in a thunderstorm, but usually lasts much longer than lightning. Scientists do not understand ball lightning very well, and some even do not think ball lightning is real, because it is so strange. However, it has been widely reported in weather journals by many trustworthy people. So, it is very possible that it is real.<br> <div>討論閃電形成的原理，一起制作手工，利用剃須泡沫當(dāng)做云朵，毛根做閃電，看起來還不錯(cuò)。</div> <b>4. Types of lightning strikes</b> <b>5. Experiment </b><br><b>Wimshurst generatorWimshurst靜電發(fā)生器</b><br>The Wimshurst electrostatic generator was invented in the 1880s. The modern version consists of two plastic discs that are rotated in opposite directions by a hand-crank and drive belt mechanism. Wimshurst靜電發(fā)生器是在1880年代發(fā)明的。 現(xiàn)代版本包括兩個(gè)塑料盤，它們通過手搖曲柄和傳動(dòng)帶機(jī)構(gòu)沿相反的方向旋轉(zhuǎn)。 <ul></ul><p></p><p>很早之前就買了這個(gè)靜電發(fā)生器，對(duì)如何發(fā)電和放電Eric已經(jīng)有了一些了解。</p><p><b>Parts of Wimshurst generator</b></p> <ul><li><b>How it works</b></li></ul>The way it works is that a number of metal foil sectors are cemented onto two discs. As the discs turn, each metal foil sector accumulates the charges through contact with brushes on bars near the front and back of the discs. Two additional pairs of brushes collect the accumulated charges and transmit them to the storage capacitor, such as a Leyden jar.<br>它的工作方式是將許多金屬箔扇區(qū)粘合到兩個(gè)圓盤上。 隨著光盤旋轉(zhuǎn)，每個(gè)金屬箔扇形都通過與光盤前后面板附近的刷子接觸而積累電荷。 另外兩對(duì)電刷收集累積的電荷并將其傳輸?shù)酱鎯?chǔ)電容器（例如萊頓瓶）<br><br>The brushes also are connected to spark gap electrodes. As the discs revolve, a high voltage spark can jump between the electrodes if they are gradually brought together. 電刷也連接到火花隙電極。 隨著圓盤旋轉(zhuǎn)，如果逐漸將它們聚集在一起，則高壓火花會(huì)在電極之間跳躍。<br><div><br></div><div><b>Generates 75,000 volts</b><br>The Wimshurst electrostatic generator can generate up to 75,000 volts. Since the current is very low, there is little danger from the high voltage, but yet it is effective for creating sparks and performing interesting static electricity experiments. Wimshurst靜電發(fā)生器可以產(chǎn)生高達(dá)75,000伏的電壓。 由于電流非常低，因此高電壓幾乎沒有危險(xiǎn)，但是它對(duì)于產(chǎn)生火花和進(jìn)行有趣的靜電實(shí)驗(yàn)非常有效。<br></div> 嘗試講解靜電發(fā)生器的工作原理，在實(shí)驗(yàn)的過程中居然還聞到了臭氧的味道，分析了高壓放電對(duì)空氣產(chǎn)生的電離，所以產(chǎn)生了臭氧，Eric立馬聯(lián)想到泡腳盆的臭氧。