Editing Atmospheric diffraction (section)

==Optical atmospheric diffraction==
{{see also|Atmospheric optics}}
[[File:SolarDiffractionCorona.jpg|thumbnail|left|Solar diffraction ring]]

When [[light]] travels through thin [[clouds]] made up of nearly uniform sized [[water]] or [[aerosol]] droplets or [[ice]] [[crystal]]s, [[diffraction]] or bending of light occurs as the light is diffracted by the edges of the particles.  This degree of bending of light depends on the wavelength (color) of light and the size of the particles.  The result is a pattern of rings, which seem to emanate from the [[Sun]], the [[Moon]], a [[planet]], or another [[astronomical object]]. The most distinct part of this pattern is a central, nearly white disk. This resembles an [[atmospheric]] [[Airy disc]] but is not actually an Airy disk. It is different from [[rainbow]]s and [[halo (optical phenomenon)|halos]], which are mainly caused by [[refraction]].

[[File:Lunarcorona.jpg|right|thumbnail|Lunar diffraction ring]]

The left photo shows a diffraction ring around the rising Sun caused by a veil of aerosol. This effect dramatically disappeared when the Sun rose high enough until the pattern was no longer visible on the Earth's surface. This phenomenon is sometimes called the [[corona (optical phenomenon)|corona effect]], not to be confused with the [[solar corona]].

On the right is a [[shutter speed|1/10-second]] [[exposure (photography)|exposure]] showing an overexposed [[full moon]]. The Moon is seen through thin vaporous clouds, which glow with a bright disk surrounded by an illuminated red ring. A longer exposure would show more faint colors beyond the outside red ring.

Another form of atmospheric [[diffraction]] or bending of light occurs when light moves through fine layers of [[particulate]] dust trapped primarily in the middle layers of the [[troposphere]]. This effect differs from water based atmospheric diffraction because the dust material is [[Opacity (optics)|opaque]] whereas water allows light to pass through it. This has the effect of [[tint]]ing the light the color of the dust particles. This tinting can vary from red to yellow depending on geographical location. the other primary difference is that dust based diffraction acts as a [[Magnification|magnifier]] instead of creating a distinct [[Halo (optical phenomenon)|halo]]. This occurs because the opaque matter does not share the lensing properties of water. The effect is to make an object visibly larger while being more indistinct as the dust distorts the image. This effect varies largely based on the amount and type of dust in the atmosphere.