Around the Sun or the Moon it is possible to see
a luminous ring, called a halo. This circle of light
appears of a pale white with sometimes a red inside
and blue colour outside.
There are three types of halos :
- The 9° halo is white and as it is located
near the Sun it is difficult to identify it.
- The 22° halo is the most common and the
brightest. It can be white or coloured according to
the number, type and position of the crystals. This
optical phenomenon is visible around 100 times a year
in Europe based on the 10 years of research.
- The halo of 46° is very large and very brilliant.
Infrequent, it is possible to see the 3,90 times a
The halos are sometimes accompanied by parhelia
on each side of the circle... It is in high latitude
that these optical phenomena are more often observed.
The halos are formed by reflection or refraction
of light of the ice crystals in clouds of
the upper floor (cirrus, cirrostratus ...) or by
aerosols in the
atmosphere. These ice crystals are composed of six-sided
prisms and cross sections at six angles
Click here to enlarge
solar halo I photography
on 10/01/2004 at 15:17
With a fujifilm S5000