水是怎样循环的?(请能用英文和图画解说吗?)
地球上的水，是在不停地运动着的。它无处不在，通过蒸发、冷凝、降水等连续不断地循环。水的循环过程具体可以分为以下三个步骤：
第一步是蒸发和蒸腾的水分子进入大气。
吸收太阳辐射热后，水分子从海洋、河流、湖泊、潮湿土壤和其他潮湿表面蒸发到大气中去；生长在地表的植物，通过茎叶的蒸发将水扩散到大气中，植物的这种蒸发作用通常又称为蒸腾。据估计，在一个生长季中0.4公顷的谷物几乎就可以蒸腾200万升的水，等于同等面积内43厘米深的水层。通过蒸发和蒸腾的水，水质都得到了纯化，是清洁水。
第二步是以降水形式返回大地。
水分子进入大气后，变为水汽随气流运动，在适当条件下，遇冷凝结形成降水，以雨或雪的形式降落到地面。降水不但给地球带来淡水，养育了千千万万的生命，同时，还能净化空气，把一些天然的和人为的污物从大气中洗去。
降水是陆地水资源的根本来源。我国多年来平均年降水量为632毫米，而全球陆地平均年降水量是834毫米。
第三步是重新返回蒸发点。
当降水到达地面时，一部分渗入地下，补给地下水；一部分从地表流掉，补给河流。地表的流水，即径流可以带走泥粒，导致侵蚀；也可以带走细菌、灰尘和化肥、农药等，因而径流常常是被污染的。最后千流归大海，水又回到海洋以及河流、湖泊等蒸发点。这就是地球上的水循环。
推动这种循环的永恒动力是太阳辐射。进入到地球上的太阳能约有23％消耗于海洋表面和陆地表面的蒸发上，当水汽凝结时，这些能量又重新释放出来。就全年平均情况来看，大约从北纬40度到南纬30度是一个广大的辐射过剩区域，而极地周围的高纬度地区是辐射亏损区。海陆之间，在不同的季节有着不同的亏损和盈余。只有把热量从盈余的地区向亏损的地区输送，才能达到全球的能量平衡。而水分循环是这种能量输送的主要途径之一。水在海洋中能够形成洋流，水又能够以气液相变的形式来大量地储存和输送能量。这种能量输送保持了全球的能量平衡，使得辐射的亏损区不至于太冷，辐射过剩区不至于太热，为生物提供了一种适宜的生活环境。
有时水循环会出现一些较特殊的情况。在高纬度和高海拔区，自大气层降下的不是水而是雪。落在极地区或山地的雪积久可成冰，水因此得到保存，算是退出循环，退出时间一般为几十年、几百年或几千年。因此，冰雪的固结与消融，影响着参与水循环的水的总量，进而影响全球海面变化。
南极冰盖和格陵兰冰盖是世界上最大的冰库。如果全部融化，海洋的水位就会上升大约60米，这意味着各大洲的沿海地区、包括许多世界级大城市都将被淹没，海平面将达到纽约曼哈顿摩天大楼的20层楼那么高。
水分循环的过程是非常复杂的。除了这种海陆之间的水分循环外，海洋有自己的洋流等水圈内部的水循环；大气圈里有随着大气环流进行的大气内部水循环；大气圈与陆地之间，大气圈与洋面之间，有着水汽形成降水，降落的水分又被蒸发的直接循环；岩石圈上存在着地表水与地下水之间的转换与循环；生物体内也有着生物水的循环等。
水分循环把地球上所有的水，无论是大气、海洋、地表还是生物圈中的水，都纳入了一个综合的自然系统中，水圈内所有的水都参与水的循环。像人体中，从饮水到水排出体外只要几个小时；大气中的水，从蒸发进入大气，到形成降水离开大气，平均来说，完成一次循环要8～10天；世界大洋中的水，如果都要蒸发进入大气，完成一次水分循环的过程，需要3000～4000年。
水分循环系统是一个水的自然净化系统。水不断地从潮湿的表面蒸发，或者从植物表面蒸腾，当水蒸气进入大气时，大部分杂质留下来。雨水到了地面经过沙石的过滤和沉淀，成为洁净的水。在这个净化过程中，海洋起着巨大的作用。太阳、海洋和大气像一个巨大的蒸馏装置，时刻不停地运转着。
由于水分循环的存在，使得水成为地球上最活跃的物质，使全球的水量和热量得到均衡调节。正是由于这种年复一年、日复一日永不停息的水分循环，才使得大气圈气象万千，使得地球表面千姿百态，生机盎然。假如水分循环停止，将再也看不到电闪雷鸣、雨雪霜雹；再也没有晴、雨、阴、云的天气变化；再也看不到江、河、湖、沼；当然更不会有森林、草原；动物与人类也将不存在。
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On Earth's water, is in does not stop the movement. Its there is noplace in, through does not evaporate, the condensation, theprecipitation and so on continuously unceasingly circulates. The watercyclic process specifically may divide into following three steps:
First step is evaporates with the transpiration hydrone enters theatmosphere.
After absorbs the solar radiating heat, hydrone from sea, rivers,lake, moist soil and other moist surface evaporation to atmosphere in;The growth in the surface plant, proliferates through stem leaf'sevaporating the water to the atmosphere in, plant's this kind ofevaporation usually is called the transpiration. It is estimated, in agrowth season 0.4 hectares grain nearly may the transpiration 200myrialiters water, be equal to in the same level area 43 centimeterdeep water level. Through evaporated with the transpiration water, thewater quality all obtained the purification, was the clean water.
Second step is returns to the earth by the precipitation form.
After the hydrone enters the atmosphere, becomes the water vapor alongwith the air current movement, under the suitable condition, meets thecondensation knot to form the precipitation, descends the ground bythe rain or the snow form. The precipitation not only brings the freshwater to the Earth, has raised the great amount life, simultaneously,but also can purify the air, washes off some natural and theartificial contamination from the atmosphere.
The precipitation is the land water resources radical origin. Ourcountry for many years the average year precipitation has been 632millimeters, but the global land average year precipitation is 834millimeters.
Third step is rereturns 蒸发点.
When the precipitation arrives the ground, part of permeatingunderground, military supplies ground water; A part falls from theplace sheet current, military supplies rivers. The surface runningwater, namely the runoff may carry off the putty grain, causes thecorrosion; Also may carry off the bacterium, the dust and the chemicalfertilizer, the agricultural chemicals and so on, thus the runofffrequently is polluted. Finally thousand class turn over to the sea,the water to return to the sea as well as the rivers, the lake and soon 蒸发点. This is on Earth's water cycle.
Impels this kind of circulation the eternal power is the solarradiation. Enters the solar energy approximately has 23% consumptionto the Earth on to the sea surface and on land surface evaporating,when the water vapor congeals, these energies rerelease. Looked on thewhole year average situation that, probably from north latitude 40 tosouth latitudes 30 is general radiations too much regions, but aroundthe polar high latitude area radiates the loss area. Between the sealand, has the different loss and the earnings in the different season.Only has the quantity of heat from the earnings area to the loss localtransportation, can achieve global the energy balance. But thehydrologic cycle is one of this kind of energy transport main ways.The water can form the ocean current in the sea, the water can be madthe liquid phase changes the form comes massively the storage and thetransportation energy. This kind of energy transport maintained theglobal energy balance, causes the radiation the loss area not as fortoo coldly, the radiation area as for too is not too much hot, hasprovided the living conditions for the biology which one kind issuitable.
Sometimes the water cycle can have some more special situation. In thehigh latitude and the high elevation area, the arrogant aerospherelowers is not Shui Er is a snow. Falls accumulates in extremely localor the mountainous region snow may become the ice, the water thereforeobtains the preservation, is withdraws from the circulation, thewithdrawal time generally is several dozens year, several hundred yearor several millenniums. Therefore, snow and ice solidifying withmelts, is affecting the participation water cycle water totalquantity, then affects the global sea level change.
The south pole ice cap and the Greenland ice cap are in the world thebiggest ice bunker. If completely melts, the sea water level can risethe about 60 meters, this meant each big continent the coastal area,is all submerged including many world-classs big city, the sea levelachieved the New York Manhattan skyscraper 20 buildings are that high.
The hydrologic cycle process is extremely complex. Besides this kindof sea land between hydrologic cycle, the sea has ocean currenthydrosphere interior the and so on own water cycle; In the aerospherehas the atmospheric internal water circulation which carries on alongwith the atmospheric circulation; Between the aerosphere and the land,the aerosphere with 洋面 between, has the water vapor to form theprecipitation, descends the moisture content the direct circulationwhich evaporates; On the lithosphere has between the surface water andthe ground water transformation and the circulation; Biological invivo also has the biological water the circulation and so on.
Hydrologic cycle Earth on all water, regardless of is the atmosphere,the sea, the surface or in the biosphere water, all has bought intoline with in a comprehensive natural system, in the hydrosphere allwater all participate in the water the circulation. In the picturehuman body, discharges in vitro from the potable water to the water solong as several hours; In the atmospheric water, from evaporatesenters the atmosphere, to forms the precipitation to leave theatmosphere, on average, completes a time of circulation to want 8 ~ 10days; In world ocean water, if all must evaporate enters theatmosphere, completes a time of hydrologic cycle the process, needs3000 ~ in 4000.
The hydrologic cycle system is a water nature purification system.Water unceasingly from moist surface evaporation, or from plantsurface transpiration, when the steam enters the atmosphere, themajority of impurities stay behind. The rain water arrived the groundafter grit filtering with the precipitation, becomes the pure water.In this purification process, the sea is playing the huge role. Thesun, the sea and the atmosphere like a huge distilling apparatus, thetime does not stop is revolving.
As a result of the hydrologic cycle existence, causes Shuicheng forthe Earth on the most active matter, causes global the water volumeand the quantity of heat is under the proportional-plus-floatingcontrol. Is precisely because this kind never ceases year after year,day after day the hydrologic cycle, only then causes the aerosphere tobe spectacular, causes the earth's surface differ in thousands ofways, vitality abundant. If the hydrologic cycle stops, again also theblind lightning flash will be thunderous, the sleet frost hail; Againalso does not have clearly, the rain, to be cloudy, the cloud weatherchange; Again also the blind river, the river, the lake, moor;Certainly cannot have the forest, the prairie; The animal and thehumanity also will not exist.
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其实也就是 蒸发>降雨>地表径流>流入大海>蒸发
Evaporates > Rains > Surface runoff > Inflow sea >Evaporates
