阴影带

日食阴影带是出现在日全食开始之前和结束之后，出现在素色表面可以看到的波浪状交替、平行移动的光线微弱^[1]。它们是由大气湍流折射所引起的闪烁 (天文学)（英语：Twinkling）现象^[2]，当太阳呈现细薄的新月形时，原本歧散的阳光因类似穿过狭缝而趋近准直光束（英语：Collimated light），在前后各约一分钟时最为明显而较易观察到^[2]^[3]^[4]。

在2017年8月21日全食期间观测到的阴影带。视频显示摊在阳光下的地面上的一张白色床单（36 x 66英寸，0.91 x 1.7米）。阴影带开始时很微弱，随着食分增加至太阳呈现新月形时才逐渐变得强烈，并在第二接触，即全食开始的时突然消失。可以在音讯上听出周遭人群的氛围：对视觉上的阴影带奇观和日全食开始的黑暗做出的反应。

阴影的细部结构是由随机的大气扰动，即微细的空气湍流模式，折射从狭窄的新月形太阳射出近似准直的光束造成。

阴影带快速滑动的运动是由于气流变化与太阳以高角度投射的角运动两相结合造成。随着月牙型的太阳变薄，阳光的准直性逐渐增加，因影带也越来越明显，直到太阳盘面完全被遮蔽，日全食开始就嘎然而止。

恒星的光也是因为同样的原因而闪烁。他们离地球太远，因而成为点光源，就很容易受到地球大气湍流的影响。这些湍流就像透镜和棱镜一，会偏移光线的路径。看着准直的星光，大气折射造成的阴影带就会穿过我们的眼睛。

历史

在公元9世纪，在一次日全食中首度被描述－－在旧冰岛诗体埃达中的一部分：女巫的预言^{[来源请求]}
在1820年，德国天文学家赫尔曼·迈尔·萨洛蒙·戈尔德施密特（Hermann Goldschmidt）注意到在日全食的前后可以看见阴影带^[5]^[6]^[7]。
在1842年，英国天文学家乔治·比德尔·艾里（George B. Airy）第一次观察日全食。他回忆说阴影带适量点之一："随着全食的逼近，墙壁和地面上出现了奇怪的光波动。景象是如此的惊人，以至于在有些地方的孩子们追赶着，并试图用手去抓住它他回忆说,阴影带是亮点之一:"随着整体的临近,墙壁和地面上出现了奇怪的光波动,如此惊人,以至于在有些地方,孩子们追赶它,试图用手抓住它。 ^[8]。"
在2008年，英国天体物理学家斯图尔特·伊夫斯（Stuart Eves）推测，阴影带可能是次声波的效应。这涉及以超音速移动的月球阴影，并引发大气的冲击波。然而，天文学教授巴里·钟斯（Barrie Jones），一位阴影带的专家指出："一般相信的理论有效，没有必要寻求另一个替代方案^[9]。"

参考资料

^ Effects During a Total Solar Eclipse Archive.is的存档，存档日期2012-07-30
^ ^2.0 ^2.1 J. L. Codona. The Scintillation Theory of Eclipse Shadow Bands. Astronomy and Astrophysics. 1986, 164: 415–27 [18 July 2017]. Bibcode:1986A&A...164..415C. ISSN 0004-6361. （原始内容存档于2019-08-13）.
^ Jones, Barrie. Explanation from Barrie Jones, Open University. [2010-07-24]. （原始内容存档于2010-07-22）.
^ Strickling, Wolfgang. Wolfgang Strickling's eclipse observations 2001 page. 2007-01-26 [24 July 2010]. （原始内容存档于2019-05-11）. The best theory for the emergence of the shadow bands is published by Codona 1986 [2]. His theory meanwhile accepted by the most scientists. ... movement of the shadow bands is caused by winds in the different atmospheric levels.
^ Guillermier, Pierre; Koutchmy, Serge. Total Eclipses: Science, Observations, Myths and Legends. Springer Publishing. 1999: 151. The phenomenon of shadow bands – a success of light and dark striations – is somewhat random. German astronomer Hermann Goldschmidt was the first to remark upon this complex refraction phenomenon, in 1820.
^ Maunder, Michael J. de F.; Moore, Patrick. Eclipses – General Principles. The Sun in Eclipse. Springer Publishing. 1998: 55. Shadow Bands. In 1820 the German astronomer Hermann Goldschmidt was the first to notice wavy lines seen across the Earth's surface just before totality. These so-called shadow bands [...]
^ Chapter IX: Shadow Bands. Memoirs 41. Royal Astronomical Society. 1857: 40–41.
^ M. Littmann, K. Willcox, F. Espenak: Totality: eclipses of the sun 2nd edition. Oxford University Press. p. 119
^ Sound 'cause of shadow spectacle'. BBC News. May 21, 2008 [2009-11-14]. （原始内容存档于2009-04-17）.

[1] Effects During a Total Solar Eclipse Archive.is的存档，存档日期2012-07-30

[codona-2] 2.0 ^2.1 J. L. Codona. The Scintillation Theory of Eclipse Shadow Bands. Astronomy and Astrophysics. 1986, 164: 415–27 [18 July 2017]. Bibcode:1986A&A...164..415C. ISSN 0004-6361. （原始内容存档于2019-08-13）.

[3] Jones, Barrie. Explanation from Barrie Jones, Open University. [2010-07-24]. （原始内容存档于2010-07-22）.

[4] Strickling, Wolfgang. Wolfgang Strickling's eclipse observations 2001 page. 2007-01-26 [24 July 2010]. （原始内容存档于2019-05-11）. The best theory for the emergence of the shadow bands is published by Codona 1986 [2]. His theory meanwhile accepted by the most scientists. ... movement of the shadow bands is caused by winds in the different atmospheric levels.

[5] Guillermier, Pierre; Koutchmy, Serge. Total Eclipses: Science, Observations, Myths and Legends. Springer Publishing. 1999: 151. The phenomenon of shadow bands – a success of light and dark striations – is somewhat random. German astronomer Hermann Goldschmidt was the first to remark upon this complex refraction phenomenon, in 1820.

[6] Maunder, Michael J. de F.; Moore, Patrick. Eclipses – General Principles. The Sun in Eclipse. Springer Publishing. 1998: 55. Shadow Bands. In 1820 the German astronomer Hermann Goldschmidt was the first to notice wavy lines seen across the Earth's surface just before totality. These so-called shadow bands [...]

[7] Chapter IX: Shadow Bands. Memoirs 41. Royal Astronomical Society. 1857: 40–41.

[8] M. Littmann, K. Willcox, F. Espenak: Totality: eclipses of the sun 2nd edition. Oxford University Press. p. 119

[9] Sound 'cause of shadow spectacle'. BBC News. May 21, 2008 [2009-11-14]. （原始内容存档于2009-04-17）.

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