日柱与上正切晕弧

2021年02月17日

Sun Pillar with Upper Tangent Arc
Image Credit & Copyright: Mike Cohea

Explanation: This was not a typical sun pillar. Just after sunrise two weeks ago in Providence, Rhode Island, USA, a photographer, looking out his window, was suddenly awestruck. The astonishment was caused by a sun pillar that fanned out at the top. Sun pillars, singular columns of light going up from the Sun, are themselves rare to see, and are known to be caused by sunlight reflecting from wobbling, hexagon-shaped ice-disks falling through Earth’s atmosphere. Separately, upper tangent arcs are known to be caused by sunlight refracting through falling hexagon-shaped ice-tubes. Finding a sun pillar connected to an upper tangent arc is extraordinary, and, initially, took some analysis to figure out what was going on. A leading theory is that this sun pillar was also created, in a complex and unusual way, by falling ice tubes. Few might believe that such a rare phenomenon was seen again if it wasn’t for the quick thinking of the photographer — and the camera on his nearby smartphone.

News from Mars: NASA Perseverance Coverage

Tomorrow’s picture: open space

太阳光柱与上正切晕弧
影像提供与版权: Mike Cohea

说明: 这不是寻常的太阳光柱。2星期前刚日落后，从美国罗德岛州普洛维敦斯市的一扇窗望出去，拍摄者突然目瞪口呆。惊讶的源头，是一根带着扇形顶部的太阳光柱。罕见的太阳光柱是从太阳垂直上指的光柱，其成因是地球大气中缓缓飘落的扁平六边形冰晶反射阳光所致。而上正切晕弧，则是阳光受到下坠的六边形冰柱折射所形成的。太阳光柱和上正切晕弧相接的景观极不寻常，因此颇费了一番功夫分析，才弄清楚到底见到了什么。较可信的假说指出，这道太阳光柱可能也是下坠的柱状冰晶，以复杂且不寻常的方式产生的。如果不是摄影者的反应够快，而且手边有配备相机的手机拍下影像，否则会很难让人置信真的有如此罕见的景观。

火星快讯：NASA毅力号着陆实况

明日的图片: open space