Lynch D K, Gedzelman S D, Fraser A B
Appl Opt. 1994 Jul 20;33(21):4580-9. doi: 10.1364/AO.33.004580.
Subsuns, Bottlinger's rings, and elliptical halos are simulated by the use of a Monte Carlo model; reflection of sunlight from almost horizontal ice crystals is assumed. Subsuns are circular or elliptical spots seen at the specular reflection point when one flies over cirrus or cirrostratus clouds. Bottlinger's rings are rare, almost elliptical rings centered about the subsun. Elliptical halos are small rings of light centered around the Sun or the Moon that rarely occur with other halo phenomena. Subsuns and Bottlinger's rings can be explained by reflection from a single crystal, whereas elliptical halos require reflection from two separate crystals. All three phenomena are colorless and vertically elongated with an eccentricity that increases with increasing solar zenith angle. For several cases of Bottlinger's rings the simulations are compared with density scans of photographs. Clouds that consist of large swinging or gyrating plates and dendritic crystals, which form near -15 °C, seem the most likely ca didates to produce the rings and elliptical halos. Meteorological evidence is presented that supports these conditions for elliptical halos. Simulations suggest that the most distinct elliptical halos may be produced by hybrid clouds that contain both horizontal and gyrating crystals.
利用蒙特卡罗模型模拟了次太阳、博特林格环和椭圆晕；假定太阳光从几乎水平的冰晶上反射。次太阳是当飞机飞越卷云或卷层云时在镜面反射点看到的圆形或椭圆形光斑。博特林格环很罕见，几乎是以次太阳为中心的椭圆环。椭圆晕是围绕太阳或月亮的小光环，很少与其他晕现象同时出现。次太阳和博特林格环可以用单晶反射来解释，而椭圆晕则需要两个单独的晶体反射。这三种现象都是无色的，并且垂直拉长，偏心率随太阳天顶角的增加而增大。对于几例博特林格环，将模拟结果与照片的密度扫描进行了比较。由大的摆动或旋转平板状和树枝状晶体组成的云，在接近-15°C时形成，似乎是产生这些环和椭圆晕的最有可能的候选者。给出了支持椭圆晕这些条件的气象证据。模拟表明，最明显的椭圆晕可能由同时包含水平和旋转晶体的混合云产生。
