澳大利亚野火引发罕见的天气现象

澳大利亚野火引发罕见的天气现象

Add fire-induced storms to the list of intense consequences from Australia's bushfires, as a wildfire season that began in October persists. Caused by several years of extremely dry conditions and hot summer temperatures (both exacerbated by climate change), occasional rain isn't enough to douse these flames — and won't, until autumn comes to the continent.

随着10月份开始的野火季的持续，火灾引发的风暴已经成为澳大利亚森林大火的严重后果之一。由于连年的极度干旱和夏季的高温(气候变化加剧了这两种情况)，偶尔的降雨不足以浇灭这些火焰——而且在秋季到来之前也不会。

Bushfires rage night and day, sometimes creating fire-induced storms and other weather conditions. (Photo: Daniel Mitchell/Shutterstock)

Thousands of people have evacuated from their homes along the eastern coast south of Sydney, 24 have died, and animals are racing to get out of harm's way. An area roughly the size of Denmark has burned, The New York Times estimates.

在悉尼南部的东海岸，成千上万的人已经从家中撤离，24人已经死亡，动物们正在争先恐后地逃离危险。据《纽约时报》估计，一块面积与丹麦相当的区域被烧毁。

The devastation is linked to the intensity of the fires, which are not just destroying bushlands and homes, but also causing local weather phenomena that have not been witnessed by humans at this scale.

这场灾难与大火的强度有关，大火不仅摧毁了丛林和家园，还造成了人类从未见过的如此规模的当地天气现象。

In March 2016, this famous 'Hiroshima strike' photo was finally corrected. It shows a pyrocumulonimbus cloud caused by the massive fires several hours after the atomic bomb was dropped, not the bomb explosion itself. It was misidentified as such for decades. (Photo: U.S. military [public domain]/Wikimedia Commons)

One of the most visually dramatic fire creations are pyrocumulonimbus (sometimes abbreviated as pyroCb) clouds. They're formed by a massive source of heat — either a fire or sometimes a volcano, and NASA describes them as the "fire-breathing dragon of clouds."

最具视觉戏剧性的火灾创造之一是火云(有时缩写为pyroCb)。它们是由巨大的热源形成的。它们是由大量的热源形成的——有时是火，有时是火山，美国宇航局将它们描述为“喷火的云龙”。

"It's when a fire gets so big, and there's so much heat released, that the airmass from the fire rises vertically into the atmosphere, but really really deep, unlike most smoke plumes," Craig Clements, director of the San Jose State University Weather Research Lab explains. "To have so many at one time is unique. This is probably the largest outbreak of pyrocumulonimbus on Earth," says Clements.

圣何塞州立大学气象研究实验室主任克雷格·克莱门茨解释说:“当火变得如此之大，释放出如此多的热量时，火的气团垂直上升到大气中，但真的非常非常深，不像大多数烟羽。一次拥有这么多是独一无二的。这可能是地球上最大的一次火山喷发。”

Because the smoke punches so deep into the upper atmosphere, hitting as high as the tropopause (the barrier between the lower atmosphere and stratosphere), it can easily be seen from space. That smoke also travels, affecting those who live far from the fires — Sydney, Canberra and Melbourne have all had multiple days of unhealthy and hazardous breathing conditions.

由于烟雾深入高层大气，到达对流层顶(低层大气和平流层之间的屏障)，所以在太空中很容易看到。这些烟雾还会传播，影响到那些远离火灾的人——悉尼、堪培拉和墨尔本都经历了多天的不健康和危险的呼吸状况。

PyroCb clouds also cause massive thunderstorms, including lightning, which can cause more fires. These storms also create intense downdrafts as hot air pushes up into the atmosphere, causing fire tornadoes, and also causes embers from the fire to travel, creating yet more fires. These "ember attacks" are dangerous for any person or animal exposed to them — imagine small pieces of woody debris on fire and flying through the air.

PyroCb云也会引起大范围的雷暴，包括闪电，这会引起更多的火灾。这些风暴还会产生强烈的下沉气流，因为热空气会向上推入大气，引发火灾龙卷风，还会导致火焰中的余烬移动，从而引发更多火灾。这些“灰烬袭击”对任何接触到它们的人或动物都是危险的——想象一下木头碎片着火并在空中飞舞。

During a recent ember attack, firefighters were able to take cover in their truck, and they told NBC News what it was like: "Everything was alight, both sides of the truck, the top — everything. It was like being in an oven."

在最近的一次余烬袭击中，消防队员得以在他们的卡车上寻找掩护，他们告诉NBC新闻:“所有东西都被点燃了，卡车的两边，顶部——所有东西。就像在烤箱里一样。”