Coronas

A circle of light quite distinct from the 22° halo can sometimes be seen around the sun or moon if there are thin clouds composed of water droplets or ice crystals of nearly uniform size. This circle is smaller, on the order of 10°, and is caused by diffraction of light by the small particles. The appearance is often that of alternating blue-green and red circles. The diffraction by a tiny opaque barrier shows the same pattern as that of an aperture of the same size and shape in an otherwise opaque screen (Babinet's principle).

The moon corona image above was taken on March 19, 2005 on a night when thin clouds were moving swiftly across the sky. The colors are subtle, but you can see a blue tint to the corona close to the moon and a reddening further out. This indicates diffraction in tiny water droplets. The shorter wavelength blue light produces diffraction maxima closer to the sun.

Glories

A rainbow band around the shadow of your aircraft seen on a cloud below is an example of a glory. For more distant clouds, the plane's shadow would be smaller, but the glory would be the same angular size if the water droplets were the same size.

The phenomenon is one of diffraction, with smaller droplets giving larger glories. The nature of the diffraction is similar to aperture diffraction, but is diffraction from the water droplets in the cloud. A small opaque circular scatterer gives a diffraction pattern like that of an aperture of the same size. Mie scattering is thought to be the mechanism controlling the intensity of light scattered back to the viewer. However, mathematical modeling of the details is quite complex. 这种现象是衍射现象，较小的水滴会产生更明显的光晕。这种衍射的性质类似于孔径衍射，但实际上是云中水滴的衍射。一个小的不透明圆形散射体会产生类似于相同尺寸孔径的衍射图样。人们认为米氏散射是控制光回射到观察者处的强度的机制。然而，对细节的数学建模相当复杂。

This photo of a glory was taken by Frank Starmer and is used by permission with all rights reserved to Frank. It is remarkable in that the second order diffraction is visible and a hint of third order.

Below are links to posted examples of glories:

NASA, glory over South Africa NASA，飞越南非	Glory from Earth Matters 地球 Matters 之荣耀	Glory by Bryan Mundt 《荣耀》作者：Bryan Mundt	Glory from helicopter, Mauna Loa, Wiki 从直升机拍摄的玛乌纳洛阿火山的荣耀

Glory on Close Cloud

This glory was observed on an approach to Anchorage through clouds which were sometimes very close, sometimes distant. At this point the aircraft shadow is larger than the glory, but as the clouds became more distant, the shadow was smaller while the glory stayed the same size. Remarkable telescoping of the shadow size occurred within the glory. 这种光辉在飞机穿过云层时被观察到，云层有时非常接近，有时则很远。此时飞机阴影比光辉大，但随着云层变得越来越远，阴影变小而光辉保持相同大小。在光辉中发生了显著的阴影大小变化。

Iridescent Clouds

The corona around the sun is often hard to see because it is close to the sun and masked by the extreme brilliance of the sun. When the same diffraction effects occur in clouds some distance from the sun which are composed of tiny uniform droplets, colorful bands or "iridescence" can be seen. The example below right shows the orientation of these iridescent clouds to the Sun, which is at the edge of the building.

Below are links to posted examples of iridescent clouds:

Iridescent alto-cumulus, Wiki 虹彩高积云，维基	Iridescent cloud edge, Wiki 虹彩云边缘，Wiki	Iridescent cloud, Finland 芬兰的虹彩云	Iridescent cloud Ober Gatlinburg 虹彩云奥伯加特林堡

Heiligenschein

The heiligenschein or "holy light" is like the glory except that it is seen as a white glow around the shadow of your head projected on fog or mist. It can also sometimes be seen around your shadow on a rough or dusty surface (in this case called the "dry heiligenschein"). The area immediately around your head's shadow may be seen as slightly brightened by "head on" incidence of light on small particles while at slightly greater distance from the head's shadow you get darkening because you begin to see the shadows of the small particles which are now being lit at a greater angle of incidence. Dew heiligenschein can be produced by retroreflection of the light focused by tiny dewdrops, while this light from droplets further from your head's shadow does not reach your eyes.

Examining dew heiligenschein a bit more closely, following the discussion of Lynch and Livingston, tiny dewdrops act as essentially spherical lenses, focusing the light at a distance of about 0.7 x the drop radius behind the drop. If that concentrated light strikes a leaf or blade of grass, part of it is retroreflected through the droplet, proceeding backward toward our eyes. The retroreflection produces the appearance of a bright diffuse glow around the viewer's head. It is spread over a few degrees by the fact that the droplet "lenses" have large amount of aberration and don't send their light back at exactly 180° .

Below are links to posted examples of heiligenschein:

Heiligenschein from grass 草的海尔盖恩现象	Heiligenschein around a balloon 气球周围的Heiligenschein现象	Heiligenschein Buz Aldrin on Moon Heiligenschein Buz Aldrin on Moon（专名或术语）	Heilgenschein in wheat field 小麦田中的海尔根现象

Specter of the Brocken

Below are links to posted examples of the Specter of the Brocken:

English Lake District 英语湖区	Spectre of the Brocken 布洛克山的影子	Spectre of the Brocken, Canary Islands 布洛克影，加那利群岛	Skiddaw Lesser Man, English Lake District 斯凯达小山，英格兰湖区