fire rainbows are a rare phenomenon which occur at rare places at specific times!

1. FIRE
RAINBOWS
MADE BY
HUSSAN ARA

2. INTRODUCTION
A lot of natural phenomenon occur every day, in front of
us, without us being known. While some of them occur
once or twice a year and they are even less noticeable.
There is another category which occurs rarely on a
specific place and on a specific time and they can only
be observed in certain conditions and those conditions
are of course rare that is why we call such phenomenon
as rare phenomenon. Occurrence of fire rainbows is one
such phenomenon which occurs rarely in certain
conditions.

3. TERMINOLOGY•“Fire Rainbows” are neither fire, nor rainbows
• But are so called because of their brilliant pastel
colors and flame like appearance.
• Technically they are known as circumhorizontal
arc
• An ice halo formed by hexagonal, plate-shaped
ice crystals in high level cirrus clouds.
• Precisely scientists call it as CHA

4. FORMATION
• A CHA is caused by the refraction though ice
crystals in cirrus clouds of light from the sun.
• Refraction happens when the speed of light is
reduced inside a particular medium.
• This particular refraction happens when light goes
from air without cloud to air containing cloud.
• In this case it is vital that the cloud is cirrus in
shape.

5. •A cirrus cloud is one of those thin,
wispy ones, often with tufts sticking
out like disheveled hair!
• They can be huge – covering so much
of the sky that you cannot see where
one ends and another begins
• When they are a massive sheet they
are called cirrostratus.

7. •At specific angle when the sunlight strikes one of the
six faces of hexagonal ice crystal it divides into various
wavelengths
•The light goes in through one of the side faces of the
crystal. Then it is refracted and it leaves through the
bottom horizontal face.
• It is vital that the crystal is aligned just so as
otherwise the light will not separate in to the rainbow
like colors we expect.
•If the alignment is correct then the whole cirrus cloud
will “explode” in to a flaming, fire rainbow!

8. CONDITIONS
The conditions required to form a “fire rainbow” are
very precise:
• The sun has to be at an elevation of 58° or greater.
• There must be high altitude cirrus clouds with plate-
shaped ice crystals, and sunlight has to enter the ice
crystals at a specific angle.
• The ice crystals in the cirrus cloud have to be
horizontal to refract the sun. If they are then the arc
is formed.

9. WHO CAN SEE IT?
•The position of the observer is also
important.
•Circumhorizontal arcs cannot be seen
in locations north of 55°N or south of
55°S.
•Likewise there are certain times of the
year when they are visible.

10. WHEN THEY OCCUR?
•Brightly colored circumhorizontal arc
occur mostly during the summer
•Between particular latitudes.
•When the sun is very high in the sky,
and that a cirrus cloud or haze be
present and contain plate-shaped ice
crystals.

14. CONCLUSION
Fire rainbows are actually an
optical phenomenon which occurs
rarely due to its requirements of
its occurrence. It is naturally
occurring and everything which is
created by nature is worth
watching and worth praising!

15. THANK
YOU!