around the equator. It can affect weather around the world

赤道周圍。它會影響世界各地的天氣

changing the odds of floods, drought, heatwaves

改變洪水、乾旱和熱浪的概率

and cold seasons for different regions even raising global temperatures.

不同地區的冷季和熱季甚至會使全球氣溫升高。

But what is El Niño and how does it happen?

什麼是厄爾尼諾現象？

Firstly we need to know what's normally happening in the tropical Pacific.

首先，我們需要了解熱帶太平洋地區的正常情況。

This vast stretch of ocean sees consistent winds

這片廣闊的海域風力持續不斷

called 'trade winds' that blow from east to west.

自東向西吹來的風被稱為'信風'。

These winds push warm water near the surface

這些風將溫暖的海水推向海面附近

in their direction of travel, so the warm water piles

在它們行進的方向上，暖水就會堆積起來

up on the western side of the ocean around Asia and Australasia

在亞洲和澳大拉西亞周圍的海洋西側出現

On the other side of the ocean around South and Central America

在大洋彼岸的南美洲和中美洲一帶

as the warmer water gets pushed away from the coast

由於較暖的海水被推離海岸

it's replaced by cold water which is pulled up from deeper down in the ocean

取而代之的是從海洋深處抽上來的冷水

a process called upwelling. This creates a temperature difference

這一過程被稱為上升流。這就產生了溫差

across the tropical Pacific with warmer water piled up in the West

在整個熱帶太平洋上，較暖的海水在西太平洋上堆積起來。

and cooler water in the east. Warmer water

東部水溫較低。水溫較高

adds extra heat to the air which causes the air to rise with more vigor

給空氣增加額外的熱量，使空氣更有活力地上升

and its this rising air that creates an area of more

這些上升的空氣會形成一個面積更大的

unsettled weather with more cloud in rainfall

天氣不穩，降雨雲量增多

That rising air in the West

西部上升的空氣

sets up atmospheric circulation across this part of the world

在這一地區形成大氣環流

with warm moist air rising on one side of the Ocean

暖溼氣流在海洋一側上升

and cooler dryer air descending on the other

而較冷的乾燥空氣則從另一方向降落

This circulation reinforces the easterly winds

這種環流加強了東風

so this part of the world sits in a self-perpetuating state

是以，世界的這一地區處於一種自我延續的狀態

until El Niño begins. If conditions are right

直到厄爾尼諾現象開始出現。如果條件合適

tropical Pacific weather systems or slow changes in the ocean around the equator

熱帶太平洋天氣系統或赤道附近海洋的緩慢變化

can set off a chain of events which weaken or even reverse the usual trade winds

會引發一連串事件，削弱甚至逆轉通常的信風

With weakened trade winds there's less push

信風減弱，推動力減少

of warm surface water to the western side

西側的溫暖表層水

of the ocean and less upwelling of cold water

減少冷水上湧

on the eastern side. This allows the usually colder parts of the ocean to warm

在東側。這使得海洋中通常較冷的部分變暖

canceling out the normal temperature difference.

抵消了正常的溫差。

Because the area of warmest water moves

因為最溫暖的水域會移動

so does the associated wet and unsettled weather.

相關的潮溼和不穩定天氣也是如此。

This changes rainfall patterns over the

這改變了

equatorial Pacific as well as the large-scale wind

赤道太平洋以及大尺度風

patterns. It's this change in winds which has a knock-on effect

模式。正是這種風向的變化產生了連鎖反應

changing temperature and rainfall in locations

各地氣溫和降雨量的變化

around the world. The main impacts

在世界各地的影響。主要影響

are around the tropics where you see an increase in the risk of floods

在熱帶地區，洪水風險增加

in Peru and droughts in Indonesia, India

祕魯的乾旱和印度尼西亞、印度的乾旱

and parts of Brazil. But virtually wherever you are in the world

和巴西部分地區。但實際上，無論您身處世界何處

El Niño has the potential to affect you directly

厄爾尼諾現象有可能直接影響您

via the weather or indirectly via socio-economic impacts

通過天氣或間接的社會經濟影響

There's another impact from El Niño which happens because of

厄爾尼諾現象還會產生另一種影響，這是因為

all the extra heat at the surface of the tropical Pacific.

熱帶太平洋表面的所有額外熱量。

This releases vast amounts of energy

這將釋放大量能量

into the atmosphere which can temporarily push up global temperatures.

進入大氣層，會暫時推高全球氣溫。

This is why El Niño years often feature

這就是為什麼厄爾尼諾年經常以

among the warmest on record. Each El Niño event

是有記錄以來最溫暖的時期之一。每次厄爾尼諾現象

is different so the global impacts can change.

不同，是以對全球的影響也會發生變化。

You can find out more about the different impacts of El Niño

您可以進一步瞭解厄爾尼諾現象的不同影響

on our website. El Niño peaks around Christmas-time

在我們的網站上。厄爾尼諾現象在聖誕節前後達到頂峰

and last for several months. It can dive back to neutral conditions

並持續數月。它可以潛回中性狀態

but sometimes reverses into La Niña.

但有時會逆轉為拉尼娜現象。

This is the flip side of the oscillation which sees

這是振盪的反面，即

a strengthening of the normal trade winds.

正常信風加強。

This pushes the warmest water to the far western part of the tropical Pacific

這將把最溫暖的海水推向熱帶太平洋的最西部

and increases the upwelling of cold water

並增加冷水上湧

in the east. This cooler water

在東部。這種較冷的水

extends out from the coast of the Americas towards the central part of the ocean

從美洲海岸向海洋中部延伸

La Niña also impacts global weather

拉尼娜現象也影響全球天氣

and tends to have opposite effects to El Niño.

並往往與厄爾尼諾現象產生相反的影響。

You can also see more about La Niña and its impacts

您還可以查看有關拉尼娜及其影響的更多資訊

on our website.

在我們的網站上。