Halo Phenomenon

A Halo, The word from Greek is an optical phenomenon produced by ice crystals creating colored or white arcs and spots in the sky. Its also know as a nimbus, icebow or gloriole. Many are near the sun or moon but others are elsewhere and even in the opposite part of the sky. They can also form around artificial lights in very cold weather when ice crystals called diamond dustare loating in the nearby air. 

There are many types of ice halos. They are produced by the ive crystals in cirrus clouds high (5–10 km, or 3–6 miles) in the upper troposphere. The particular shape and orientation of the crystals is responsible for the type of halo observed. Light is reflected and refracted by the ice crystalsand may split up into colors because of dispersion. 

The crystals behave like prisms and mirrors, refracting and reflecting sunlight between their faces, sending shafts of light in particular directions. Atmospheric phenomena such as halos were used as part of weather lore as an empirical means of weather forecasting before meteorology was developed. 

Other common optical phenomena involving water droplets rather than ice crystals include the glory and the rainbow.

An optical phenomenon is any observable event that results from the interaction of light and matter. A mirage is an example of an optical phenomenon.

Common optical phenomena are often due to the interaction of light from the sun or moon with the atmosphere, clouds, water, dust, and other particulates. One common example is the rainbow, when light from the sun is reflected and refracted by water droplets.
                                       

A Circular Halo Is a diffraction disc or airy disc has similar appearance but is a disc rather than a ring, and has a red border on the inside. Its size depends on the size of the ice or water particles that cause it. These are also known as coronas but are not to be confused with the thin streaming luminous gas that makes up the sun's own corona.

Thats is Halo, its a normal phenomenon, very seldom and rare to appear in atmosphera. Its like rainbow but rainbow always appear and its beautifull. ;)

Its happen on Tuesday, October 2, 2012.