- 鐵幣
- 12074 元
- 文章
- 2082 篇
- 聲望
- 2768 枚
- 上次登入
- 18-6-10
- 精華
- 1
- 註冊時間
- 07-9-14
- UID
- 448041
|
地震 EARTHQUAKES
地震（又稱地動、地振動）是地殼快速釋放能量過程中造成的振動，期間會產生地震波。
地震可由地震儀所測量，地震的震級是用作表示由震源釋放出來的能量，通常以芮氏地震規模來表示；烈度則透過「修訂麥加利地震烈度表」來表示，某地點的地震烈度是指地震引致該地點地殼運動的猛烈程度，是由震動對個人、傢具、房屋地質結構等所產生的影響來斷定。
在地球的表面，地震會使地面發生震動，有時則會發生地面移動。震動可能引發山泥傾瀉甚或火山活動。如地震在海底發生，海床的移動甚至會引發海嘯。
一般而言，地震一詞可指自然現象或人為破壞所造成的地震波。人為自然地形的破壞、大量氣體（尤其是沼氣遷移或提取、水庫蓄水、採礦油井注水、地下核試等；自然的火山活動、大型山崩、地下空洞塌陷、大塊隕石墜落等均可引發地震。
震動的發源處稱為震源。大多數震源都在地殼和上地幔頂部，即岩石圈內。根據震源的深度，地震可分為三類：淺源地震（深度在0-70公里）、中源地震（深度在70-300公里）和深源地震（深度在300公里以上）。由震源豎一垂直線至地面上的位置稱為震央。震央是地表距離震源最近的地方，因此地震波最早到達這處，震動也最為強烈，破壞程度也最大。
目前破壞級數: 以4級至12級（或可能更高）
目前死亡人數最高記錄:
吉尼斯世界記錄大全-險難篇死亡人數最多的地震 1201年7月，發生在地中海東部的地震約造成110萬人死亡，傷亡主要發生在埃及和敘利亞。
Earthquakes, also called temblors, can be so tremendously destructive, it’s hard to imagine they occur by the thousands every day around the world, usually in the form of small tremors.
Some 80 percent of all the planet's earthquakes occur along the rim of the Pacific Ocean, called the "Ring of Fire" because of the preponderance of volcanic activity there as well. Most earthquakes occur at fault zones, where tectonic plates—giant rock slabs that make up the Earth's upper layer—collide or slide against each other. These impacts are usually gradual and unnoticeable on the surface; however, immense stress can build up between plates. When this stress is released quickly, it sends massive vibrations, called seismic waves, often hundreds of miles through the rock and up to the surface. Other quakes can occur far from faults zones when plates are stretched or squeezed.
Scientists assign a magnitude rating to earthquakes based on the strength and duration of their seismic waves. A quake measuring 3 to 5 is considered minor or light; 5 to 7 is moderate to strong; 7 to 8 is major; and 8 or more is great.
On average, a magnitude 8 quake strikes somewhere every year and some 10,000 people die in earthquakes annually. Collapsing buildings claim by far the majority of lives, but the destruction is often compounded by mud slides, fires, floods, or tsunamis. Smaller temblors that usually occur in the days following a large earthquake can complicate rescue efforts and cause further death and destruction.
Loss of life can be avoided through emergency planning, education, and the construction of buildings that sway rather than break under the stress of an earthquake.
海嘯來襲 TSUNAMI
海嘯是一種具有強大破壞力的海浪。當地震發生於海底，因震波的動力而引起海水劇烈的起伏，形成強大的波浪，向前推進，將沿海地帶一一淹沒的災害，稱之為海嘯。海嘯在許多西方語言中稱為“tsunami”，詞源自日語“津波”，即「港邊的波浪」（「津」即「港」）。這也顯示出了日本是一個經常遭受海嘯襲擊的國家。漢字又稱海溢，韓語來源。詞，在1963年的國際科學會議上正式列入國際術語。目前，人類對地震、火山、海嘯等突如其來的災變，只能通過觀察、預測來預防或減少它們所造成的損失，但還不能阻止它們的發生海啸通常由震源在海底下50千米以内、里氏地震規模6.5以上的海底地震引起。海啸波长比海洋的最大深度还要大，在海底附近傳播也没受多大阻滞，不管海洋深度如何，波都可以传播过去，海嘯在海洋的傳播速度大約每小時五百到一千公里，而相鄰兩個浪頭的距離也可能遠達500到650公里，當海嘯波進入陸棚後，由於深度變淺，波高突然增大，它的這種波浪運動所卷起的海濤，波高可達數十米，並形成“水牆”。由地震引起的波動與海面上的海浪不同，一般海浪只在一定深度的水層波動，而地震所引起的水體波動是從海面到海底整個水層的起伏。此外，海底火山爆发，土崩及人為的水底核爆也能造成海嘯。此外，隕石撞擊也會造成海嘯，“水牆”可達百尺。而且隕石造成的海嘯在任何水域也有機會發生，不一定在地震帶。不過隕石造成的海嘯可能千年才會發生一次。海嘯等自然災害都會產生次聲波，大象可以聽到次聲波，像2004年印度洋大地震產生的海嘯，由于大象聽到海嘯產生的次聲波，不聽主人指揮，快速離開現場，乘坐大象的遊客才得以生還。
現時尚未有一個完整的科學定義，但多會形容波高達到40至100米以上的海嘯，而一般的海嘯波高只有10至15米。大海嘯可由大山崩及小型天體撞擊地球產生，在襲擊低窪地區時，其海浪可到達距離海岸20公里遠。
A tsunami is a series of ocean waves that sends surges of water, sometimes reaching heights of over 100 feet (30.5 meters), onto land. These walls of water can cause widespread destruction when they crash ashore.
These awe-inspiring waves are typically caused by large, undersea earthquakes at tectonic plate boundaries. When the ocean floor at a plate boundary rises or falls suddenly it displaces the water above it and launches the rolling waves that will become a tsunami.
Most tsunamis, about 80 percent, happen within the Pacific Ocean’s “Ring of Fire,” a geologically active area where tectonic shifts make volcanoes and earthquakes common.
Tsunamis may also be caused by underwater landslides or volcanic eruptions. They may even be launched, as they frequently were in Earth’s ancient past, by the impact of a large meteorite plunging into an ocean.
Tsunamis race across the sea at up to 500 miles (805 kilometers) an hour—about as fast as a jet airplane. At that pace they can cross the entire expanse of the Pacific Ocean in less than a day. And their long wavelengths mean they lose very little energy along the way.
In deep ocean, tsunami waves may appear only a foot or so high. But as they approach shoreline and enter shallower water they slow down and begin to grow in energy and height. The tops of the waves move faster than their bottoms do, which causes them to rise precipitously.
A tsunami’s trough, the low point beneath the wave’s crest, often reaches shore first. When it does, it produces a vacuum effect that sucks coastal water seaward and exposes harbor and sea floors. This retreating of sea water is an important warning sign of a tsunami, because the wave’s crest and its enormous volume of water typically hit shore five minutes or so later. Recognizing this phenomenon can save lives.
A tsunami is usually composed of a series of waves, called a wave train, so its destructive force may be compounded as successive waves reach shore. People experiencing a tsunami should remember that the danger may not have passed with the first wave and should await official word that it is safe to return to vulnerable locations.
Some tsunamis do not appear on shore as massive breaking waves but instead resemble a quickly surging tide that inundates coastal areas.
The best defense against any tsunami is early warning that allows people to seek higher ground. The Pacific Tsunami Warning System, a coalition of 26 nations headquartered in Hawaii, maintains a web of seismic equipment and water level gauges to identify tsunamis at sea. Similar systems are proposed to protect coastal areas worldwide.
龍捲風 TORNADOES
龍捲風，又稱龍捲、龍吸水等，是一種相當猛烈的天氣現象，由快速旋轉並造成直立中空管狀的气流形成。龍捲風大小不一，但形狀一般都呈上大下小的漏斗状，“漏斗”上接稱雨雲（極少數情況下為積雲雲底），下部一般與地面接觸並且時常被一團塵土或碎片殘骸等包圍。大多數龍卷風直徑約75米，風速在64千米每小時至177千米每小時之間，可橫掃數千米。還有一些龍卷風風速可超過480千米每小時，直徑達1.6千米以上，移動路經超過100公裡。雖然除南極洲外的每塊大陸都發現有龍卷風，但美國遭受的龍卷風比其他任何國家或地區都多。除此之外，龍卷風在加拿大南部、亞洲中南部和東部、南美洲中東部、非洲南部、歐洲西北部和東南部、澳大利亞西部和東南部以及新西蘭等地區皆常有出現。
Tornadoes are vertical funnels of rapidly spinning air. Their winds may top 250 miles (400 kilometers) an hour and can clear-cut a pathway a mile (1.6 kilometers) wide and 50 miles (80 kilometers) long.
Twisters are born in thunderstorms and are often accompanied by hail. Giant, persistent thunderstorms called supercells spawn the most destructive tornadoes.
These violent storms occur around the world, but the United States is a major hotspot with about a thousand tornadoes every year. "Tornado Alley," a region that includes eastern South Dakota, Nebraska, Kansas, Oklahoma, northern Texas, and eastern Colorado, is home to the most powerful and destructive of these storms. U.S. tornadoes cause 80 deaths and more than 1,500 injuries per year.
A tornado forms when changes in wind speed and direction create a horizontal spinning effect within a storm cell. This effect is then tipped vertical by rising air moving up through the thunderclouds.
The meteorological factors that drive tornadoes make them more likely at some times than at others. They occur more often in late afternoon, when thunderstorms are common, and are more prevalent in spring and summer. However, tornadoes can and do form at any time of the day and year.
Tornadoes' distinctive funnel clouds are actually transparent. They become visible when water droplets pulled from a storm's moist air condense or when dust and debris are taken up. Funnels typically grow about 660 feet (200 meters) wide.
Tornadoes move at speeds of about 10 to 20 miles (16 to 32 kilometers) per hour, although they've been clocked in bursts up to 70 miles (113 kilometers) per hour. Most don't get very far though. They rarely travel more than about six miles (ten kilometers) in their short lifetimes.
Tornadoes are classified as weak, strong, or violent storms. Violent tornadoes comprise only about two percent of all tornadoes, but they cause 70 percent of all tornado deaths and may last an hour or more.
People, cars, and even buildings may be hurled aloft by tornado-force winds—or simply blown away. Most injuries and deaths are caused by flying debris.
Tornado forecasters can't provide the same kind of warning that hurricane watchers can, but they can do enough to save lives. Today the average warning time for a tornado alert is 13 minutes. Tornadoes can also be identified by warning signs that include a dark, greenish sky, large hail, and a powerful train-like roar.
火山爆發 VOLCANOS
火山是地下深處的高溫岩漿及其有關的氣體、碎屑從地殼中噴出而形成的，具有特殊形態的地質結構。火山可以分為死火山和活火山，一段時間內沒有噴發的活火山叫做睡火山休眠火山）。另外還有一種泥火山，它在科學上嚴格來說不屬于火山，但是許多社會大眾也把它看作是火山的一種類型。火山爆發是一種很嚴重的自然災害，它常常伴有地震。因此火山噴發會對人類造成危害，但同時它也帶來一些好處。例如：可以促進寶石的形成；擴大陸地的面積夏威夷群島就是由火山噴發而形成的）；作為觀光旅遊考察景點，推動旅遊業，如日本的富士山。專門研究火山活動的學科稱為火山學。
Volcanoes are awesome manifestations of the fiery power contained deep within the Earth. These formations are essentially vents on the Earth's surface where molten rock, debris, and gases from the planet's interior are emitted.
When thick magma and large amounts of gas build up under the surface, eruptions can be explosive, expelling lava, rocks and ash into the air. Less gas and more viscous magma usually mean a less dramatic eruption, often causing streams of lava to ooze from the vent.
The mountain-like mounds that we associate with volcanoes are what remain after the material spewed during eruptions has collected and hardened around the vent. This can happen over a period of weeks or many millions of years.
A large eruption can be extremely dangerous for people living near a volcano. Flows of searing lava, which can reach 2,000 degrees Fahrenheit (1,250 degrees Celsius) or more, can be released, burning everything in its path, including whole towns. Boulders of hardening lava can rain down on villages. Mud flows from rapidly melting snow can strip mountains and valleys bare and bury towns. Ash and toxic gases can cause lung damage and other problems, particularly for infants and the elderly. Scientists estimate that more than 260,000 people have died in the past 300 years from volcanic eruptions and their aftermath.
Volcanoes tend to exist along the edges between tectonic plates, massive rock slabs that make up Earth's surface. About 90 percent of all volcanoes exist within the Ring of Fire along the edges of the Pacific Ocean.
About 1,900 volcanoes on Earth are considered active, meaning they show some level of activity and are likely to explode again. Many other volcanoes are dormant, showing no current signs of exploding but likely to become active at some point in the future. Others are considered extinct.
WIlDFIRE 山火(又稱野火)
山火，又稱野火、林火、森林大火、森林火災，是一種通常發生在林野間難以控制的火情。通常是由閃電引起的，其他一些常見的原因有人為疏忽、故意縱火、火山爆發和火山碎屑雲，熱浪、乾旱和週期氣候轉變如厄爾尼諾現象都會戲劇性增加山火危機。
乾旱以及小型的森林火災是促成極大的森林大火的主要因素。
Uncontrolled blazes fueled by weather, wind, and dry underbrush, wildfires can burn acres of land—and consume everything in their paths—in mere minutes.On average, more than 100,000 wildfires, also called wildland fires or forest fires, clear 4 million to 5 million acres (1.6 million to 2 million hectares) of land in the U.S. every year. In recent years, wildfires have burned up to 9 million acres (3.6 million hectares) of land. A wildfire moves at speeds of up to 14 miles an hour (23 kilometers an hour), consuming everything—trees, brush, homes, even humans—in its path.There are three conditions that need to be present in order for a wildfire to burn, which firefighters refer to as the fire triangle: fuel, oxygen, and a heat source. Fuel is any flammable material surrounding a fire, including trees, grasses, brush, even homes. The greater an area's fuel load, the more intense the fire. Air supplies the oxygen a fire needs to burn. Heat sources help spark the wildfire and bring fuel to temperatures hot enough to ignite. Lightning, burning campfires or cigarettes, hot winds, and even the sun can all provide sufficient heat to spark a wildfire.Although four out of five wildfires are started by people, nature is usually more than happy to help fan the flames. Dry weather and drought convert green vegetation into bone-dry, flammable fuel; strong winds spread fire quickly over land; and warm temperatures encourage combustion. When these factors come together all that's needed is a spark—in the form of lightning, arson, a downed power line, or a burning campfire or cigarette—to ignite a blaze that could last for weeks and consume tens of thousands of acres.
These violent infernos occur around the world and in most of the 50 states, but they are most common in the U.S. West, where heat, drought, and frequent thunderstorms create perfect wildfire conditions. Montana, Idaho, Wyoming, Washington, Colorado, Oregon, and California experience some of the worst conflagrations in the U.S. In California wildfires are often made worse by the hot, dry Santa Ana winds, which can carry a spark for miles.Firefighters fight wildfires by depriving them of one or more of the fire triangle fundamentals. Traditional methods include water dousing and spraying fire retardants to extinguish existing fires. Clearing vegetation to create firebreaks starves a fire of fuel and can help slow or contain it. Firefighters also fight wildfires by deliberately starting fires in a process called controlled burning. These prescribed fires remove undergrowth, brush, and ground litter from a forest, depriving a wildfire of fuel.Although often harmful and destructive to humans, naturally occurring wildfires play an integral role in nature. They return nutrients to the soil by burning dead or decaying matter. They also act as a disinfectant, removing disease-ridden plants and harmful insects from a forest ecosystem. And by burning through thick canopies and brushy undergrowth, wildfires allow sunlight to reach the forest floor, enabling a new generation of seedlings to grow.
AVALANCHES 雪崩
俗稱白色雪龍，是在长年积雪的山中常有的自然災害，每年都有很多人死於雪崩。產生原因通常是覆雪處於一種「危險」的平衡狀態下，如果稍微有外力作用，就會失去平衡，造成雪塊滑動，進而引起更多的覆雪運動，使大量的積雪瞬間傾盆而下；附近的人及村莊往往不能倖免。一般雪崩還有乾版雪崩和硬版雪崩。
While avalanches are sudden, the warning signs are almost always numerous before they let loose. Yet in 90 percent of avalanche incidents, the snow slides are triggered by the victim or someone in the victim's party. Avalanches kill more than 150 people worldwide each year. Most are snowmobilers, skiers, and snowboarders.
Many avalanches are small slides of dry powdery snow that move as a formless mass. These "sluffs" account for a tiny fraction of the death and destruction wrought by their bigger, more organized cousins. Disastrous avalanches occur when massive slabs of snow break loose from a mountainside and shatter like broken glass as they race downhill. These moving masses can reach speeds of 80 miles (130 kilometers) per hour within about five seconds. Victims caught in these events seldom escape. Avalanches are most common during and in the 24 hours right after a storm that dumps 12 inches (30 centimeters) or more of fresh snow. The quick pileup overloads the underlying snowpack, which causes a weak layer beneath the slab to fracture. The layers are an archive of winter weather: Big dumps, drought, rain, a hard freeze, and more snow. How the layers bond often determines how easily one will weaken and cause a slide.
Storminess, temperature, wind, slope steepness and orientation (the direction it faces), terrain, vegetation, and general snowpack conditions are all factors that influence whether and how a slope avalanches. Different combinations of these factors create low, moderate, considerable, and high avalanche hazards.
If caught in an avalanche, try to get off the slab. Not easy, in most instances. Skiers and snowboarders can head straight downhill to gather speed then veer left or right out of the slide path. Snowmobilers can punch the throttle to power out of harm's way. No escape? Reach for a tree. No tree? Swim hard. The human body is three times denser than avalanche debris and will sink quickly. As the slide slows, clear air space to breathe. Then punch a hand skyward.
Once the avalanche stops, it settles like concrete. Bodily movement is nearly impossible. Wait—and hope—for a rescue. Statistics show that 93 percent of avalanche victims survive if dug out within 15 minutes. Then the survival rates drop fast. After 45 minutes, only 20 to 30 percent of victims are alive. After two hours, very few people survive.
FLOODS 洪水(也稱水災)
洪災也稱水災或氾濫，是由洪水引發的一种自然災害，指河流、湖泊、海洋所含的水体上漲，超過常規水位的水流现象。洪水常威嚇沿河、湖濱、近海地区的安全，甚至造成淹没災害。當一個地方被河水、海水或雨水淹蓋時，這個地方就是遇上了洪災。 洪災是因自然降水過量或排水不及時造成的人員傷亡、財物損失、建築倒塌等现象。洪災發生時不單會淹浸沿海地區，洪水更會破壞農作物，淹死牲畜，沖毀房屋。 此外，氾濫使商業活動停頓、學校停課、古蹟文物受破壞，水電、煤氣供應中斷。洪水更會污染食水，傳播疾病。 洪水一般会给人类带来灾难，稱為洪災，如黄河、恒河下游地区泛滥成災，造成巨大的損失。另一方面，卻也有一些洪水現象會给人類带來益處，如尼羅河定期的泛濫，给下游三角洲平原带来大量肥沃的泥沙，有利農業生產。 「洪水」一詞一說取自一河川名，其源流大約在今日中國河南輝縣（舊名「共」）及其東鄰各縣境內，「洪水」與淇水會合後流入黃河。當地黃河轉折處的北岸，正是黃河水患開始的地方。該處起源於輝縣的為共、龔、段三姓。一種說法稱古代中國大禹所治之水，即在今日輝縣境內，大概以當時的人力物力，尚不能治理江河。因此「洪」一字即源自輝縣舊稱「共」，「洪水」也就是「共地之水」。
There are few places on Earth where people need not be concerned about flooding. Any place where rain falls is vulnerable, although rain is not the only impetus for flood.A flood occurs when water overflows or inundates land that's normally dry. This can happen in a multitude of ways. Most common is when rivers or streams overflow their banks. Excessive rain, a ruptured dam or levee, rapid ice melting in the mountains, or even an unfortunately placed beaver dam can overwhelm a river and send it spreading over the adjacent land, called a floodplain. Coastal flooding occurs when a large storm or tsunami causes the sea to surge inland.Most floods take hours or even days to develop, giving residents ample time to prepare or evacuate. Others generate quickly and with little warning. These flash floods can be extremely dangerous, instantly turning a babbling brook into a thundering wall of water and sweeping everything in its path downstream.
Disaster experts classify floods according to their likelihood of occurring in a given time period. A hundred-year flood, for example, is an extremely large, destructive event that would theoretically be expected to happen only once every century. But this is a theoretical number. In reality, this classification means there is a one-percent chance that such a flood could happen in any given year. Over recent decades, possibly due to global climate change, hundred-year floods have been occurring worldwide with frightening regularity.
Moving water has awesome destructive power. When a river overflows its banks or the sea drives inland, structures poorly equipped to withstand the water's strength are no match. Bridges, houses, trees, and cars can be picked up and carried off. The erosive force of moving water can drag dirt from under a building's foundation, causing it to crack and tumble.
In the United States, where flood mitigation and prediction is advanced, floods do about $6 billion worth of damage and kill about 140 people every year. A 2007 report by the Organization for Economic Cooperation and Development found that coastal flooding alone does some $3 trillion in damage worldwide. In China's Yellow River valley, where some of the world's worst floods have occurred, millions of people have perished in floods during the last century.
When floodwaters recede, affected areas are often blanketed in silt and mud. The water and landscape can be contaminated with hazardous materials, such as sharp debris, pesticides, fuel, and untreated sewage. Potentially dangerous mold blooms can quickly overwhelm water-soaked structures. Residents of flooded areas can be left without power and clean drinking water, leading to outbreaks of deadly waterborne diseases like typhoid, hepatitis A, and cholera.
But flooding, particularly in river floodplains, is as natural as rain and has been occurring for millions of years. Famously fertile floodplains like the Mississippi Valley in the American Midwest, the Nile River valley in Egypt, and the Tigris-Euphrates in the Middle East have supported agriculture for millennia because annual flooding has left millions of tons of nutrient-rich silt deposits behind.
Most flood destruction is attributable to humans' desire to live near picturesque coastlines and in river valleys. Aggravating the problem is a tendency for developers to backfill and build on wetlands that would otherwise act as natural flood buffers.
Many governments mandate that residents of flood-prone areas purchase flood insurance and build flood-resistant structures. Massive efforts to mitigate and redirect inevitable floods have resulted in some of the most ambitious engineering efforts ever seen, including New Orleans's extensive levee system and massive dikes and dams in the Netherlands. And highly advanced computer modeling now lets disaster authorities predict with amazing accuracy where floods will occur and how severe they're likely to be.
LIGHTNING雷電
閃電，在大氣科學中指大氣中的強放電現象。在夏季的雷雨天氣雷電現象較為常見。它的發生與雲層中氣流的運動強度有關。有資料顯示，冬季下雪時也可能發生雷電現象，即雷雪，但是發生機會相當微小。若有嚴重的火山爆發時，空中可能出現短路，出現閃電。
閃電的放電作用通常會產生了閃電光或電光。雷電起因一般被認為是雲層內的各種微粒因為碰撞摩擦而積累電荷，當電荷的量達到一定的水平，等效于雲層間或者雲層與大地之間的電壓達到或超過某個特定的值時，會因為局部電場強度達到或超過當時條件下空氣的電擊穿強度從而引起放電。空氣中的電力經過放電作用急速地將空氣加熱、膨脹，因膨脹而被壓縮成電漿，再而產生了閃電的特殊構件雷（衝擊波的聲音）。目前對於放電具體過程的認識還不能透徹明白，一般被認為和長間隙擊穿的現象相類似。
閃電的電流很大，其峰值一般能達到幾萬安培，但是其持續的時間很短，一般只有幾十微秒。所以閃電電流的能量不如想象的那麼巨大。不過雷電電流的功率很大，對建築物和其他設備尤其是電器設備的破壞十分巨大，所以需要安裝避雷針或避雷器等以在一定程度上保護這些建築和設備的安全。
Lightning Can Strike Twice
Cloud-to-ground lightning bolts are a common phenomenon—about 100 strike Earth’s surface every single second—yet their power is extraordinary. Each bolt can contain up to one billion volts of electricity.
This enormous electrical discharge is caused by an imbalance between positive and negative charges. During a storm, colliding particles of rain, ice, or snow increase this imbalance and often negatively charge the lower reaches of storm clouds. Objects on the ground, like steeples, trees, and the Earth itself, become positively charged—creating an imbalance that nature seeks to remedy by passing current between the two charges.
A step-like series of negative charges, called a stepped leader, works its way incrementally downward from the bottom of a storm cloud toward the Earth. Each of these segments is about 150 feet (46 meters) long. When the lowermost step comes within 150 feet (46 meters) of a positively charged object it is met by a climbing surge of positive electricity, called a streamer, which can rise up through a building, a tree, or even a person. The process forms a channel through which electricity is transferred as lightning.
Some types of lightning, including the most common types, never leave the clouds but travel between differently charged areas within or between clouds. Other rare forms can be sparked by extreme forest fires, volcanic eruptions, and snowstorms. Ball lightning, a small, charged sphere that floats, glows, and bounces along oblivious to the laws of gravity or physics, still puzzles scientists.
Lightning is extremely hot—a flash can heat the air around it to temperatures five times hotter than the sun’s surface. This heat causes surrounding air to rapidly expand and vibrate, which creates the pealing thunder we hear a short time after seeing a lightning flash.
Lightning is not only spectacular, it’s dangerous. About 2,000 people are killed worldwide by lightning each year. Hundreds more survive strikes but suffer from a variety of lasting symptoms, including memory loss, dizziness, weakness, numbness, and other life-altering ailments.
為保留原文的權威性，所以保留原文以便相互參照，另外我在轉貼的時候，發現下面有人回應說，好像有圖片有爭議，有點扯到敏感的政治議題，希望各位版友能幫忙找出謝謝。 |
|
傳送訊息
發表於 10-4-20 23:08:03
