美不胜收 澳大利亚现罕见雨幡洞云

Amazing photographs have emerged capturing one of the sky’s rarer sights – a cloud formation known as a fallstreak hole.
这些精彩照片拍下了一种罕见的天象——雨幡洞云。

Also known as a ‘hole punch cloud’ the unusual occurrence, which appears in the sky as an ethereal groove gently capturing a mini-rainbow, is formed when tiny water droplets freeze suddenly into ice crystals and drop rapidly through the air, leaving behind the appearance of a hole.
这一现象又称穿洞云，看起来像空中飘荡的盛有迷你彩虹的辙印。这一现象的成因是空中的小水滴迅速冻结成冰晶，坠落时在云中留下了一个空洞。

Residents of seaside town Wonthaggi, in Victoria, Australia, were quick to take to social media to capture the unusual event at around lunchtime yesterday.
澳大利亚维多利亚省的海边小镇旺萨吉居民昨天中午通过社交媒体迅速捕捉到这一稀有现象。

As well as admiring the beautiful shape, some citizens were concerned this could herald the end of the world with one tweeting: "Rapture's here, folks."
人们虽然欣赏云洞的美丽，却也担心这是世界末日的前兆。有人在推特上写到：“兄弟们，天国近了。”
小编注：被提（Rapture）是指世界末日时，或者的基督徒会被送上天与基督同在。

Fortunately, it was nothing so exciting.
幸运的是，什么都没发生。

Fallstreak holes happen usually in high or mid-level clouds, which are composed of water droplets that are already at a temperature colder than freezing.
雨幡洞云通常发生在中高空云层。那里的水滴温度低于冰点。

These ‘supercool’ droplets are frozen  when – for example – a plane passes through the cloud and brings with it ice crystals which causes the water droplets to freeze. This process is known as seeding according to Science Magazine.
这些过冷液滴在遇到小冰晶时会冻结。例如一架飞机飞过后就会如此。《科学》杂志把这一过程称为“播种”。