高中英语Unit 1 The world of our senses-Section 2 Background informationVIP

Unit 1 The world of our sensesSection 2: Background informationabout fog and sharkI. The London fogLondon used to be famous for its heavy fog. This was because people in London burned coal which gave out heavy smoke, a polluted form that actually is called smog. In 1873, a coal-smoke smog, thicker and more persistent than natural fog, covered the city for days and caused 268 deaths. Another fog in 1879 lasted from November to March and caused four long months of sunshineless darkness. In 1952, a four-day fog killed about 4,000 Londoners. It was not until then that some measures were taken to stop the heavy fog. In 1956, Parliament enacted the Clean Air Act, Which effectively reduced the burning of coal. It was the beginning of a series of air-pollution reforms in England. Now the air in London is quite cleanthough the city still sometimes is covered in a clean, ordinary fog.II. Understanding fog and cloudsFog is a cloud based on the ground, rather than in the atmosphere. Fog forms when there is a lot of moisture near the ground, or when the air near the ground cools to the dew point. The temperature to which air must be cooled in order for the water vapor in the air to condense into liquid water is known as the dew point. If air near the ground cools to this temperature, water vapor from the air will become visible as dew on the ground or fog in the air.Clouds are usually the most obvious feature of the sky. They both reflect weather patterns and play a role in what the weather does. The links below take you to a great deal of information about clouds.Locations of cloudsLow-level clouds: (generally found below 6,500 feet) Low-level clouds are usually composed of liquid water droplets, but they can have snow and ice crystals in cold weather.Mid-level clouds: (generally found between 6,500 and 23,000 feet) Most mid-level clouds are composed of liquid water droplets during summer and a liquid droplet-ice crystal mix during winter. Mid-level cloud names are preceded by an alto prefix.High-level clouds: (generally found above 20,000 feet) High-level clouds are composed of ice crystals and tend to be very thin and wispy. High-level cloud names are preceded by a cirro prefix.Different kinds of fog, where fog formsAdvection fog forms when humid air flows over cold ground or water.Radiation fog forms on generally clear, cool nights.Steam fog forms over water, often in the fall.Overnight rain can enhance fog that forms in the morning.Precipitation fog forms when rain or snow falls. As precipitation falls into drier air below the cloud, the liquid drops or ice crystals evaporate or sublimate directly into water vapor. The water vapor increases the moisture content of the air while cooling the air. This often saturates the air below the cloud and allows fog to form.Upslope fog is very common along large hills and mountains. It forms when winds blow up the side of a hill or mountain, which cools the air.Valley fog forms in mountain valleys during winter and can be more than 1,500 feet thick. Often, the winter sun is not strong enough to evaporate the fog during the day. When the air cools again the following night, the fog often becomes thicker, which makes it even harder for the sun to burn it off the following day. These fogs can last for several days until strong winds blow the moist air out of the valley. The tendency for cool, dense air to pool at the bottom of valleys also enhances valley fog.III. The introduction of sharksSharks are amazing fish that have been around since long before the dinosaurs existed. They live in waters all over the world, in every ocean, and even in some rivers and lakes. Unlike bony fish, sharks have no bones; their skeleton is made of cartilage, which is a tough, fibrous substance, not nearly as hard as bone. Sharks also have no swim bladder (unlike bony fish).Size There are many different species of sharks that range in size from the size of a persons hand to bigger than a bus. Fully-grown sharks range in size from 7 inches (18cm) long (the Spined Pygmy shark), up to 50 feet (15m) long (the Whale shark). Most sharks are intermediate in size, and are about the same size as people, 5-7 feet (1.5-2.1m) long. Half of the 368 shark species are under 39 inches (1m) long.Body Sharks have a variety of body shapes. Most sharks have streamlined, torpedo-shaped bodies that glide easily through the water. Some bottom-dwelling sharks have flattened bodies that allow them to hide in the sand of the ocean bed. Some sharks have an elongated body shape. Varieties of sharks There are about 368 different species of sharks, which are divided into 30 families. These different families of sharks are very different in the way they look, live, and eat. They have different shapes, sizes, color, fins, teeth, habitat, diet, personality, method of reproduction, and other attributes. Some types of shark are very rare (like the great white shark and the megamouth) and some are quite common (like the dogfish shark and bull shark). The Tiger sharksThey are not native to Hawaii and can be found swimming in tropical and subtropical waters world wide and in some temperate seas. Tiger sharks go from the surface to 131 feet.( 40m) They inhabit both the shoreline and open waters, ranging perhaps up to 500 miles. The tiger shark is in deep coastal waters in the day and near the shore at night. Scientists now believe that tiger sharks are constantly swimming over larger distances in search of prey rather than being territorial. They are most responsible for the shark attacks in Hawaii which averages two to three attacks a year. It is known as one of the three main sharks known to attack humans. It is very aggressive to humans. In Hawaii, the tiger shark is known as the Auma Kua or ancestor spirits.The Great White SharkIt is one of the seas paramount predators and a creature of deep fascination to many people. As sharks go, the Great White is huge and particularly beautiful, featuring bold pigmentation, dark eyes, and a built-in smile. It also gives an impression of having a charming personality, a strange mix of curiosity and timidity that belies its enormity and power.The Great White is among the most widely distributed of sharks, owing - in part - to its ability to maintain its body temperature up to 27F (15C) warmer than the surrounding seawater.Great White Sharks often prey upon seals and sea lions in areas where they are locally abundant.The Great White is unusual among sharks in that it sometimes raises its head out of the water, apparently to observe activity above the surface.Due to its curiosity about floating objects and predation upon marine mammals (which are air-breathing and must surface to ventilate their lungs), the Great White is more likely to be observed by surface-bound people than are most sharks.Divers occasionally encounter solitary Great Whites underwater. Usually, the shark seems to check them out visually, becomes disinterested after a few passes, and swims away. However, one must not count on it: this is a potentially very dangerous wild animal and divers who encounter one while diving would be wise to leave the water immediately.IV. Translation of reading雾比尔洛大雾警报那天早晨波莉离开家的时候，整个城市就已笼罩在一片灰雾中了。午餐时分，收音机里气象员报告说，到下午就会变成浓雾。四点钟，波莉下了班，踏进浓雾之中。她不知道这个时候公交车是不是还照常运行。没有公交车前往国王街一到街上，波莉就急匆匆地向往常乘车的车站走去。“你要去哪里?”售票员问。“国王街，”波莉说。“对不起，小姐，售票员答道，“现实情况是雾太大了，公交车开不了那么远。你不妨乘地铁去格林公园吧。那里的天气说不定会好一些，你在那里也许能够搭乘上一辆出租车。”高个子男人正当波莉打量地铁里的乘客时，她感觉到有一个穿黑色外套的男人在注视着她。终于，地铁到达格林公园站。当其他乘客陆续下车的时候，波莉扫视了一下周围的面孔。这时，高个子男人不见了。脚步声等波莉到达地铁入口处时，那里已空无一人。外面，大雾就像片浓密的灰云在笼罩着。什么人也看不见。于是，波莉向花园街走去。走着走着，波莉听到了一阵脚步声，可等她到街道拐角处，脚步声又消失了。忽然，波莉觉得有一只粗糙的手拂了一下她的睑，随即就有个男人的声音在她耳边响起：“对不起。”男人走开了。她能感到由于害怕自己的心脏在砰砰乱跳。热心的陌生人接着，她又听到了那种声音-在她身后响起的轻柔的脚步声。刚才她还盼望着能有什么人朝她这里走过来，然而现在她想到的是逃跑，只是由于恐惧她站在那里一动也不能动。脚步声这会儿好像近了。接着，黑暗中传来了一个男人的声音。“有人吗?”波莉等了等。最后，她还是说话了：“你好，我想我是迷路了。”没过几秒钟，有一只手伸了过来，碰了碰她的胳膊。波莉发现自己身边站着个男人，他的手搭在她的胳膊上。她仰头凝视对方，看到的是一张老人的脸。“也许我能帮你。你要去哪条路?”他问。“我住在国王街86号。”波莉答道。“握住我的手，”老人说，“跟我来，不用担心。”老人牵着波莉的手。“当心，这儿有台阶。”老人的另一只手里拄着一根拐杖。波莉听到了拐杖敲击台阶的声音。“我至今还记得有几次厉害的大雾，可那也许是你还没有出生前的事了。我看不见你的脸，但你的声音听上去很年轻。你多大了?”“刚二十，”波莉说道。“啊，二十!多好的年龄啊。我也曾年轻过呢。我们到拐角了。这里左转弯。”“我现在是彻底迷路了。您肯定认识路吗?”波莉又开始觉得恐惧了。