Tuesday, August 16, 2011

Physics Context: Fire Rainbow

Atmospheric phenomenon was known as arc circum-horizon or Fire Rainbow (rainbow fire), will appear when the sun is high (more than 58 degrees above the horizon). Sunlight shone through straight and cirrus clouds, thus producing a kind of crystal slabs and formed hexagon prism effect. So it looks like a rainbow-shaped flame.

Let us try to understand what exactly a rainbow of fire is and how nature can create such stunning scenery. In the language of meteorologists and physicists, Fire Rainbow (rainbow fire) is known as symmetric circum-horizontal lower arc 46 degrees arc plate or just a short CHM. In scientific language, it is classified as 'Ice Halo'. Another name for the phenomenon is circum-horizon arc and lower symmetrical 46 ° plate arc. 

The term "fire rainbow" has also been used to describe this phenomenon, although strictly speaking not a rainbow arc. It is produced by refraction (slow light) in a cloud of ice crystals are placed in a typical type called 'Cirrus Clouds'. Full circle in a rainbow of fire is a collection of various colors, seen parallel to the horizon in the presence of cirrus clouds. Center of the circle is always under the sun.

How Rainbow Fire can happen? Through observation and study, meteorologists have found the right conditions that can cause a fire rainbow or CHM. For if a fire rainbow is formed, the Sun has always been high in the sky, often observed is at an elevation angle of 58 degrees or more. Also needed is a cirrus cloud that has a large number of plate-shaped ice crystals. Your position is also important to be in the proper location to be able to see the rainbow fire. It is a known fact, that the rainbow flame is not visible at position 55 degrees North latitude north or south of 55 degrees of south latitude. There is a myth that the halo is rare. How often it is seen depends on the location and, in particular, the latitude. In the United States is a relatively common halo seen several times each summer in one place. In contrast, fire rainbow very rare in the mid-latitudes and northern Europe.

If you ask a physicist about how the optical halo case, then you should understand about the definition of light refracting through ice crystals of certain types. An optical halo occurs when the sun enters and oriented horizontally on flat ice crystals with hexagon shape of the vertical face on the side and came out near the face at the bottom. In principle, Parry oriented crystals column can also produce the arc - although this is rare.

90 ° inclination between the entrance and exit rays produces good facial color spectrum that are separated and, if the crystal alignment right, makes the entire cirrus clouds appear to shine.

An arc can be difficult to distinguish from circus-horizontal infra-lateral arc when the sun is high in the sky. The former is always parallel to the horizon while the two curves upward at its ends.

Refraction event this creates a 90 degree angle between the incoming and outgoing rays that produce color scattered group of well separated and clearly visible. As the crystals form, it is oriented at an angle toward the Sun and at the right height to form a rainbow of fire.

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