Tornado! 龍捲風來襲!

A tornado touches down near Elie, Manitoba, Canada on June 22, 2007. 六月二十二日，龍捲風降臨加拿大曼尼托巴省的艾利鎮。 PHOTO: AP

This is a photo of a tornado that hit a small town in Canada on June 22. It was one of three reported in Canada that day. Four homes were destroyed by the tornado, but luckily no one was injured.

Tornadoes can happen anywhere in the world, but the most tornadoes are seen in a place called Tornado Alley in the Mid-west of the US.

Scientists don't fully understand tornadoes, but one theory is that they form when a warm wind meets a cold wind.

A thunderstorm high up in the atmosphere makes the layers of air move. The warm humid air from near the ground gets pushed up into the cold dry air above it. If the wind changes speed and direction, then a tornado might form.

As the two winds spiral round they form a vortex. The wind can reach up to 480km an hour! That's very strong. Tornadoes can pick up objects, animals, and even people sometimes.

If you ever see a tornado you should make sure that you get into shelter as fast as possible.

這是六月二十二日侵襲加拿大某個小鎮的龍捲風照片，據說是當天在加拿大發生的三場龍捲風之一。這場龍捲風摧毀了四間民舍，所幸無人受傷。

世界各地都有龍捲風發生，但全球龍捲風最多的地方是美國中西部的「龍捲風小徑」。

科學家並未完全了解龍捲風，但有一種理論說，當溫暖的空氣遇上冷空氣時，龍捲風就可能成型。

大氣層高空降下大雷雨時，層層的空氣就會流動。靠近地面濕暖的風，就會向上流到乾冷風中。假如風改變了速度與方向，龍捲風就可能成形。

這兩種風旋轉時，會形成渦流。風速可達每小時四百八十公里，相當強勁！龍捲風會捲走物品、動物，甚至於人類。

假如你看到了龍捲風，務必儘快躲進避難所。

TODAY'S WORDS 今日單字 1. injure v.i. /v.t. 傷害 (shang1 hai4)，受傷 (shou4 shang1) 例: I injured my ankle while playing ball. (我打球時傷了腳踝。) 2. form v.i. /v.t. 形成 (xing2 cheng2)，成立 (cheng2 li4) 例: We've decided to form a drama society. (我決定成立戲劇社。) 3. vortex n. 渦流 (wo1 liu2) 例: A whirlpool is an example of a vortex. (漩渦是渦流的一例。) 4. shelter n. 避難所 (bi4 nan4 suo3) 例: When it started to rain we ran for shelter. (開始下雨時，我們跑向避雨處。)