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FireRainbow
THIS IS A FIRE RAINBOW - ONE OF
THE RAREST NATURALLY OCCURRING ATMOSPHERIC PHENOMENA.
THE PICTURE WAS CAPTURED THIS WEEK ON THE IDAHO/WASHINGTON BORDER.
THE EVENT LASTED ABOUT 1 HOUR.
CLOUDS HAVE TO BE CIRRUS, AT LEAST 20K FEET IN THE AIR, WITH JUST THE
RIGHT AMOUNT OF ICE CRYSTALS AND THE SUN HAS TO HIT THE CLOUDS AT
PRECISELY 58 DEGREES.
THIS
IS REAL. BELOW IS WHAT SNOPES
SAYS: Miller
Origins:
This is a real photograph of an atmospheric phenomenon known as
a circumhorizon(tal)
arc, the example shown above was captured on camera as it
hung for about an hour across a several-hundred square mile area of sky
above northern Idaho (near the Washington border) on 3 June
2006.
In general, a circumhorizontal arc (or "fire rainbow") appears when the
sun is high in the sky (i.e., higher than 58° above the horizon),
and its light passes through diaphanous, high-altitude cirrus clouds
made up of hexagonal plate
crystals. Sunlight entering the crystals' vertical side
faces and leaving through their bottom faces is refracted
(as through a prism) and separated into an array of visible colors.
When the plate crystals in cirrus clouds are aligned optimally (i.e.,
with their faces parallel to the ground), the resulting display is a
brilliant spectrum of colors reminiscent of a rainbow.
Last updated: 5
July 2006
