Review geography knowledge (3):

(復習地理知識)

How is weather different from climate?

天氣與氣候有何不同？

  Sunlight falls at varying angles onto the Earth's surface, heating up each of its regions differently. The difference in temperature eventually leads to different types of weather. A climate is when particular weather conditions prevail in a place for an extended period of time. So we can talk about the weather tomorrow or this month, but when we talk of climate we are talking of much longer time periods-decades or even centuries.

  陽光以不同的角度照射在地球表面，這樣每個區域的溫度就不同。溫度的差異最終導致不同類型的天氣。氣候是指一個地方在一段較長時間內出現的特定天氣狀況。因此，我們可以談論明天或本月的天氣，但當我們談論氣候時，我們談論的是更長的几十年甚至几個世紀的時間段。

What is a season?

什麼是季節？

  A season is a period within a year defined by distinct weather. The tilt in the Earth's axis is responsible for seasons. In temperate and polar regions four seasons are recognized--spring, summer, autumn and winter. Some tropical and subtropical regions have a rainy season (sometimes called a monsoon season) and a dry season, while others have hot, rainy and cool seasons.

  季節是一年中定義不同天氣的一段時間。因爲地軸的傾斜度直接影響到了季節的變化。在溫帶和極地地區會有四個分明的季節。那就是春季，夏季，秋季和冬季。而在一些熱帶和亞熱帶地區一般來說會有雨季（有時稱爲季風）和旱季的區別，而其他地區會有熱季，雨季和涼季。

What are the factors that influence weather on the Earth?

影響地球天氣的因素有哪些？

  Temperature, rainfall, wind, cloud and atmospheric pressure are the main factors that influence weather patterns across the world. Wind is caused by the unequal heating off the Earth's surface. When the air above a certain region becomes warm and high, it rises and heavier , cooler air sweeps across from another area to take its place. This movement of air is called wind. (The wind always blows from an area of ????high pressure to an area of ????low pressure. )  。       Atmospheric pressure also affects the movement of wind, which always flows from a region of high pressure to that of low pressure. The difference in pressure between the two areas determines the speed with which the wind blows. If there is a small difference, we feel a breeze. If the difference is large, it leads to a storm. If the wind is flowing over a large water body such as a sea, it can pick up moisture and carry clouds and rain with it. Low pressure usually means stormy weather and rain, while high pressure usually means lots of sun and not much wind. There are other factors, such as the ocean currents created by the Earth rotation, which also influence weather. 

  溫度， 降雨，風，云和大氣壓力是影響世界各地天氣模式的主要因素。風是由地球表面不均勻加熱引起的。當某個區域上方的空氣變暖變高時，它會上升并變重。 較冷的空氣從另一個區域吹過來取代它。這種空氣運動稱爲風。（風從高壓區吹向低壓區。）大氣壓力也會影響風的運動，風總是從高壓區流向低壓區。兩個區域之間的壓力差決定了風吹的速度。如果壓力差很小，我們會感覺到有微風。如果壓力差很大，就會引發暴風雨。如果風流經過大海等大片水域時，它會吸收水分并攜帶云和雨。低壓通常意味着暴風雨天氣和降雨，而高壓通常意味着陽光充足，風力不大。另外還有其他因素，比如地球自轉產生的洋流，也會影響天氣。

How are clouds formed?

云是如何形成的？

  The Sun's heat causes water in the oceans, rivers and lakes to evaporate and form water vapor. The warm water vapor rises upward, and as it rises, it cools down. As a result, the water vapor in the air condenses to form clouds containing tiny droplets of water. These droplets grow larger in size and finally fall down as rain. Sometimes, the temperature is so low that these droplets freeze into ice crystals and fall down as snow.

  在太陽的照射下，熱量使海洋，河流以及湖泊中的水分不停的蒸發，就形成了水蒸汽。而溫暖的水蒸汽在上升的過程中會冷卻下來。結果，空氣中的水蒸汽就凝結成云。在云中含有微小的水滴。當這些水滴逐漸變大時，最后會以雨水的形式降落下來。有時， 溫度太低，云中的水滴就會凍結成冰晶，然后會以雪的形式降落下來。

The water cycle:

水的循環：

  All the water in the Earth's atmosphere, both on its surface and underground, is a part of the water cycle. The water is recycled again and again. 

  The water cycle is the continuous movement of water within the Earth's atmosphere and water. Including:  Evaporation, Transpiration, Condensation, Precipitation and collecttion. Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain and snow.

  地球大氣中的所有水，包括地表水和地下水，它們都是水循環的一部分。這些水可以一遍又一遍的循環。

  水的循環是在地球大氣中不停的運動當中進行的。水循環的過程包括：蒸發，蒸騰，凝結，沉澱和收集。當液態水蒸發后成爲水蒸汽再凝結成云，又會以降雨或降雪的形式回到地面。

  (1) Evaporation:

  蒸發

  When water is exposed to sunlight and high temperatures , it changes from a liquid to a gas, or water vapor.

  當水暴露在陽光和高溫下時，它會從液體變成氣體或水蒸汽。

  (2) Transpiration:

  蒸騰作用：

  When water evaporates from plants through openings in their leaves, called stomata.

  植物中的水分是通過葉片上的氣孔蒸發出來的。

  (3) Condensation: 

  凝結

  When water vapor in the air turns back into liquid water forming clouds . This process occurs as warm water vapor rises through the atmosphere, where the cool air causes the water vapor to condense.

  當空氣中的水蒸氣重新變成液態水形成云時，這一過程發生與暖水蒸汽上升到大氣中時，遇到冷空氣導致水蒸汽凝結。

  (4) Precipitation:

  降水

  When water droplets in clouds become too heavy and big for the air to hold, they fall back to Earth as rain, snow, hail , sleet, or freezing rain. This is the main way that atmospheric water returns to the Earth's surface.

  當云中的水滴變得太重太大而空氣托不住的時候，它們就會以雨，雪，冰雹，雨夾雪或凍雨的形式落到地面。這是大氣中的水返回地球表面的主要方式。

   (5) Collection:

  收集

  The collection is the stage of the water cycle where water is temporarily collected and stored. as water returns to the earth's surface, it will run-off into our rivers, streams, lakes, and glaciers. 

  收集是水循環中的一個階段。在循環的時候， 水被暫時收集和儲存。當水回到地球表面時，它會流入我們的河流，溪流，湖泊和冰川中。

  地理常識有些來自《Planet Earth》, 有些來自網絡。

  New Words: (生詞)

  prevail : 存在，盛行，流行。

  tilt : 傾斜

  Earth's axis: 地軸

  temperate: 溫和的

  monsoon : 季風

  transpiration: 蒸騰作用

  stomata: 氣孔

  sleet: 雨夾雪

  run-off：排出，流失，逃跑

  願人們的生活更美好，願和平的陽光普照大地。