What are they?

它們是什麼？

Why and where do they blow?

為什麼會吹，吹到哪裡去？

And finally, what are their effects?

最後，它們有什麼影響？

The term faune describes a warm, dry wind that blows down the lee or downwind side of a mountain.

faune（風）一詞描述的是一種溫暖、乾燥的風，從山的背風面或順風面吹下。

The term was first used to describe a wind that often blows in springtime in the Alpine valleys in Switzerland and Austria, but the name is now used for a variety of dry warm winds around the world, including the Chinook in the Rocky Mountains, the Santa Ana Wind in California, the Zonda in South America and the Loo in India.

這個詞最早是用來形容一種經常在春天吹拂瑞士和奧地利阿爾卑斯山谷的風，但現在這個名字被用來形容世界各地的各種乾燥暖風，包括落基山脈的奇努克風、加利福尼亞的聖安娜風、南美洲的宗達風和印度的盧風。

So let's see how faune winds are formed.

讓我們來看看動物風是如何形成的。

When winds encounter a mountain high enough to block their passage, the air is pushed up along its flanks, and as the air rises, it cools down.

當風遇到一座足以阻擋它們通過的高山時，空氣就會沿著山的側面被推高，隨著空氣的上升而降溫。

In fact, as the air rises, it experiences less and less pressure.

事實上，隨著空氣的上升，它所承受的壓力會越來越小。

This is because the higher the air is, the less air molecules are above it, so air particles experience less and less weight on them.

這是因為空氣越高，上方的空氣分子就越少，是以空氣粒子所承受的重量也就越來越小。

So when air is pushed up a mountain, the drop in pressure allows the air to expand.

是以，當空氣被推上山時，壓力的下降會使空氣膨脹。

But to expand, the air has to give out some energy to its surroundings, and this causes it to become colder.

但為了膨脹，空氣必須向周圍環境釋放一些能量，這就導致空氣變冷。

This process is known as adiabatic cooling, and causes the temperature of the rising air to drop at a rate of approximately 1°C for every 100 meters of elevation.

這個過程被稱為絕熱冷卻，每上升 100 米，上升空氣的溫度就會下降約 1°C。

This rate is known as the dry adiabatic lapse rate.

這個速率被稱為幹絕熱失效率。

But that is not all.

但這還不是全部。

Cold air can contain less water vapor than warm air.

冷空氣所含的水蒸氣可能比暖空氣少。

So as the air cools below a certain temperature, it cannot retain all the water it initially had when it started rising.

是以，當空氣冷卻到一定溫度以下時，就無法保留最初上升時的所有水分。

We say it becomes saturated, and droplets start to form.

我們說它變得飽和，水滴開始形成。

This leads first to clouds, and eventually to rain.

這首先導致了雲，最終導致了雨。

The elevation at which this happens is known as the lifting condensation level.

發生這種情況的海拔高度被稱為提升冷凝水準。

Now, because condensation causes latent heat to be released, as the air rises above the condensation level, it keeps on cooling adiabatically, but at a much slower rate, since part of the cooling effect linked to expansion is offset by heat released by condensation.

現在，由於冷凝會釋放出潛熱，當空氣上升到冷凝水準以上時，會繼續絕熱降溫，但降溫速度要慢得多，因為冷凝釋放的熱量抵消了與膨脹有關的部分降溫效果。

So, instead of cooling 1°C every 100 meters, the rate drops by almost half to approximately 0.6°C per 100 meters.

是以，降溫速度從每 100 米 1°C 下降到每 100 米約 0.6°C，幾乎下降了一半。

This reduced rate of cooling is known as the wet adiabatic lapse rate.

這種降低的冷卻速度被稱為溼絕熱失效率。

Eventually, the rising air reaches the top of the mountain.

最終，上升的空氣到達了山頂。

By this stage, it will have cooled down a lot, and likely it will have lost most of its humidity, so we are now dealing with cold, dry air.

到了這個階段，溫度會降低很多，溼度可能也會降低很多，所以我們現在面對的是寒冷乾燥的空氣。

Cold and dry air is heavy, and will start to sink, rushing down the lee side of the mountain.

乾冷的空氣很重，會開始下沉，從山的背面衝下來。

Now, the opposite phenomenon happens.

現在，相反的現象發生了。

The air that sinks becomes compressed, and it warms up.

下沉的空氣被壓縮，溫度升高。

By how much?

多少錢？

Well, because the air is now dry, it will follow the dry adiabatic lapse rate, and warm up by 1°C per 100 meters, or almost twice as fast as it cooled down on the upwind side.

那麼，由於空氣現在是乾燥的，它將遵循乾燥絕熱失效率，每 100 米升溫 1°C，或幾乎是上風側降溫速度的兩倍。

By the time fern winds reach the valley, they will be not only dry, but also much warmer than they were on the other side of the mountain.

當蕨類植物的風吹到山谷時，它們不僅會變得乾燥，而且會比山那邊暖和得多。

Fern winds can have some beneficial effects, as warmer climates can favour certain cultures.

蕨風可以產生一些有益的影響，因為溫暖的氣候有利於某些文化的發展。

It is, for example, partially thanks to fern wind that wine can be produced in the Alps.

例如，阿爾卑斯山之所以能釀造葡萄酒，部分原因就在於蕨風。

But often, the effects of fern can be devastating.

但蕨類植物的影響往往是毀滅性的。

In fact, fern winds can attain considerable speeds and cause a lot of damage.

事實上，蕨類風可以達到相當高的速度，造成很大的破壞。

People in California particularly dread the Santa Ana winds, because they are known to promote wildfires.

加利福尼亞人尤其害怕聖安娜風，因為眾所周知，聖安娜風會助長野火。

The Loo causes a lot of sufferance in India too, where it makes temperature rise to dangerous levels.

在印度，"盧 "也造成了很多痛苦，它使氣溫上升到危險的水準。

Finally, in springtime in the Alps, the sudden increase in temperature linked to fern wind can cause the rapid melting of snow and cause avalanches and inundations.

最後，在阿爾卑斯山的春季，與蕨類風有關的氣溫突然升高會導致積雪迅速融化，引發雪崩和洪水。

This concludes our today's video.

今天的視頻到此結束。

If you found it interesting, I hope you will help us produce more videos like this by subscribing to our channel.

如果您覺得有趣，我希望您能通過訂閱我們的頻道，幫助我們製作更多這樣的視頻。

Thank you so much for watching and I hope to see you soon!

非常感謝您的收看，希望很快能見到您！