奇怪的波浪形状的云滚过皮斯加山

(Photo: Grant W. Goodge/Wikimedia Commons)

At first glance, you might assume this image is the result of some elaborate Photoshop trick, but trust us, it's 100 percent real!

乍一看，你可能会认为这张照片是ps出来的，但是相信我们，这是百分百真实的!

These bizarre, tubular clouds spotted looming over Mount Pisgah in Asheville, North Carolina, were created by a Kelvin-Helmholtz instability, a natural phenomenon that occurs when there's a difference in velocity between two interacting fluids. The clouds are named after Lord Kelvin and Hermann von Helmholtz, who studied the physics behind this beautiful phenomenon. An example almost everyone has seen is when wind blows over water.

这些奇怪的管状云隐约出现在北卡罗来纳州阿什维尔的皮斯加山上，它们是由凯尔文-亥姆霍兹不稳定性造成的，这是一种自然现象，当两种相互作用的流体的速度不同时，就会发生这种不稳定性。这些云是以开尔文勋爵和赫尔曼•冯•赫姆霍尔兹的名字命名的，他们研究了这一美丽现象背后的物理学。一个几乎每个人都见过的例子是风吹过水面。

It works like this: First, air is pushed up the steep slopes of the mountain to form clouds in a process known as "orographic lift." Next, swift winds collide with those newly formed clouds, and the resulting Kelvin-Helmholtz instability causes them to curl like giant ocean waves. As EarthSky explains, The clouds are a good indication of instability, meaning if you see these when you fly, it might be a bumpy flight.

它的工作原理是这样的：首先，空气被推到陡峭的山坡上形成云，这个过程被称为“地形抬升”。接下来，疾风与这些新形成的云发生碰撞，由此产生的凯尔文-亥姆霍兹不稳定性使它们像巨大的海浪一样卷起。正如EarthSky解释的那样，这些云是不稳定的一个很好的迹象，这意味着如果你在飞行时看到这些云，可能是一次颠簸的飞行。

More proof that fact is often stranger than fiction.

事实往往比小说更能证明这一点。