南北兩極大不同

想象一下，如果有人用布條把你的眼睛蒙住，讓你在原地轉(zhuǎn)幾圈，然后把你帶到北極或南極去。當(dāng)你到了那里摘下眼罩，如何才能知道自己是身在南極還是北極呢？地球的兩極不是一個(gè)樣子嗎？

其實(shí)，地球兩極的樣子大有不同。下面就告訴你區(qū)分南北兩極的辦法。

Look for a Marker

Earth spins on its axis1)， an imaginary line that runs through its center. The two points where this line would stick out of earth (if the line were real) are called the poles， north and south.

On a globe you can find the poles easily. They are usually where the globe is connected to its stand. But it's not so easy to find the poles on Earth itself.

The South Pole is marked. The marker sits on a glacier2)， which is on a mountain on the continent of Antarctica. The ice flows downhill about an inch a day， so a new pole marker is placed at the real South Pole each year.

But there's no marker at the North Pole. Even if someone stuck one in the ice， it wouldn't stay in one spot for very long. The ice at the North Pole is always moving， breaking up， and shifting around. That's because the ice at the North Pole is floating on the Arctic3) Sea.

Measure the Ice

Dig down into the ice. Using only three or four yardsticks4)， you could measure the ice under your feet at the North Pole. The floating ice is less than ten feet thick in most places.

But if you were at the South Pole， you would need at least two thousand yardsticks to measure the ice under your feet. It's more than a mile thick.

Check a Thermometer

Of course， the weather is always changing， even at the poles. But generally the South Pole is much colder than the North Pole. In fact， the coldest temperature ever recorded at the South Pole was -130 degree Fahrenheit5). That's more than 30 degrees colder than the coldest recorded temperature near the North Pole.

Search for Animals

As you might guess， more kinds of animals live in the Arctic (the region around the North Pole). In fact， more than forty kinds of land mammals6) live in the Arctic region. These include some big ones， like polar bears， musk7) oxen， caribou8)， and reindeer9). Way down south， there are no animals that live only on the land. Antarctica's big creature， such as seals and penguins， make their home along the coast. But they spend much of their lives in the sea.

Watch for People

Only water and ice lie under the North Pole， but there's plenty of land elsewhere in the Arctic. Many peoples have lived there for generations. For example， the Inuit live in Arctic regions of North America， and the Yakut10) live in Northern Asia.

But no one lives permanently11) in Antarctica. Scientists stay at research stations for months at a time， but they must bring all their food with them or have it brought in by airplanes.

Look for the Sun

At the poles， the Sun doesn't rise and set every day of the year. At the North Pole， the Sun never sets from the end of April through the end of August. At the South Pole， it never rises during those months. From the end of October to the end of February it's just the opposite—all sun at the South Pole and no sun up north. That makes for some very long days and nights.

The reason for the long days and nights is that Earth tilts12) at an angle to the Sun， just as a globe tilts on its stand. Each of Earth's poles faces toward the Sun and then away from it for months at a time.

搜尋標(biāo)記

地球繞著地軸轉(zhuǎn)動，地軸是一條人們假想的穿過地球中心的線。這條線穿過地球與地平面相交(如果這條線是真的)的兩點(diǎn)被稱為地極，也就是北極和南極。

你可以不費(fèi)吹灰之力就在地球儀上找到南北兩極——它們通常都在地球儀與其底座的連接處。然而，要在地球上找到南北兩極可就沒這么容易了。

人們在南極點(diǎn)放置標(biāo)桿作為標(biāo)記。這個(gè)標(biāo)桿就插在一塊冰川上，這塊冰川覆蓋在南極洲大陸的一座山脈上。冰川上的冰每天會向山下滑動大約一英寸，因此，每年人們都會在真正的南極點(diǎn)上放置新的極地標(biāo)桿。

而北極點(diǎn)則沒有標(biāo)記。就算你往冰層插入標(biāo)桿，這個(gè)標(biāo)桿也不會在一個(gè)地方停留很長時(shí)間。北極的冰層一直在移動，開裂，四處浮動。這是因?yàn)楸睒O的冰層都漂浮在北冰洋上。

測量冰層

從冰面向下挖掘。在北極，只需三到四個(gè)碼尺，你就能量出腳下冰層的厚度。大多數(shù)地方的浮冰的厚度還不足10英尺。

但是如果在南極，你至少需要兩千個(gè)碼尺來測量腳下冰層的厚度。它的厚度超過一英里。

看溫度計(jì)

當(dāng)然，天氣是不斷變化的，即便是在極地也不例外。但一般而言，南極比北極要冷得多。事實(shí)上，在南極測到的最低溫度是零下130華氏度。這比在北極附近測到的最低溫度還要低30度。

尋覓動物

你或許能猜到，在(北極附近的)北極地區(qū)居住著更多種類的動物。事實(shí)上，北極地區(qū)居住著40多種陸生哺乳動物。這其中有的個(gè)頭很大，比如北極熊、麝牛、北美馴鹿和馴鹿。而遠(yuǎn)在南極，則沒有純粹的陸生動物。南極洲的大型動物，比如海豹和企鵝，就沿著海岸居住。但是它們一生中大部分時(shí)間都是在海里度過的。

尋找人類

雖然北極下面只有水和冰，但是北極地區(qū)的其他地方也有大片陸地。許多民族世世代代生活在那里。例如因紐特人住在北美洲的北極地區(qū)，雅庫特人居住在亞洲的北端。

但是，沒有人永久地居住在南極洲。雖說科學(xué)家們每次在南極考察站一呆就是幾個(gè)月，但是他們必須帶上所有的食物，或者由飛機(jī)將食物空運(yùn)過去。

觀察太陽

在南北兩極，太陽不是一年365天都起起落落。在北極，從四月底一直到八月底，太陽都不會落下。而在南極，太陽在這幾個(gè)月內(nèi)都不會升起。從十月底到次年二月底，情況則剛好相反——南極的太陽終日不落，而北極卻沒有太陽升起。這就導(dǎo)致了許多個(gè)漫長的白天和黑夜。

產(chǎn)生漫長的白天和黑夜的原因是，地球和太陽之間有個(gè)傾斜夾角，它就像地球儀底座上的那個(gè)球體一樣傾斜著。地球的兩個(gè)極地每次都有好幾個(gè)月面朝太陽，然后再有好幾個(gè)月背對太陽。

As you can see， there are many differences between the Arctic and the Antarctic. In fact， they're poles apart! Now that13) you know the differences， which one would you like to visit?

如此看來，北極和南極有許多不同之處。事實(shí)上，它們是兩個(gè)極端！既然你知道了二者有這些不同點(diǎn)，那么，你想訪問南極還是北極呢？