Explanation: What's happening over the horizon? Although the scene may appear somehow supernatural, nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays. To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight indeed travels along straight lines, the projections of these lines onto the spherical sky are great circles. Therefore, the crepuscular rays from a setting (or rising) sun will appear to re-converge on the other side of the sky. At the anti-solar point 180 degrees around from the Sun, they are referred to as anticrepuscular rays. Pictured above is a particularly striking set of anticrepuscular rays photographed in 2001 from a moving car just outside of Boulder, Colorado, USA.
感谢疾风kid同好翻译:
译文:
地平线上发生了什么事情?尽管这景象有些神奇,其实只不过是平常的夕阳和一些位置特别合适的云朵所造成的“反云隙光”。上图正是反云隙光。要了解它们,请先想象平时随时可见的“云隙光”——也就是从云端倾泻而下的阳光,虽然光的确是沿着直线前进,然而当这些光线投射到球形的天空中则是个大圆。于是,由夕阳(或旭日)产生的云隙光看起来像在天空的另一边再度会合了。在地球上相对太阳180度的那一边所看到的光,就称为反云隙光。很多景象我们平时都曾见过,只是由于没太关注而忽视了。上图这张引人注目的反云隙光照片,是一个有心人在行进的汽车上拍下来的。
来源:NASA
[ 本帖最后由 水星人 于 2008-11-19 21:03 编辑 ] |
|