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                          P R I S M S    I N    T H E     S K Y

                 This page is dedicated to the frequent  and spectacular phenomena of color and beauty that are seen in the sky. From rainbows and a variety  of halos, crowns, iridescent clouds, sunsets and sunrises that are called "Atmospheric Optics",  that is a consequence of the interplay of the light with the air, water or ice.

                                          RAINBOW AND OTHER ARCHES

                 When a low Sun lights from our backs at a rainfall, should appear in the sky a circular arch of 42º in the direction of the shade of our head. The shade marks the anti-solar point, the direction opposed of the sun.
                The more low it is the Sun, higher will be the rainbow, being long and large.Are frequent at dusk or dawn.
                If the Sun is higher than 42º above the horizon, the main rainbow will totally  below the horizon and, it can only be visible if there are plenty of waterdrops between the observer's eye and the soil.
               The inside edge of the main or primary rainbow it is always violet and, the outside red.
               When the primary is conspicuos,  it is visible a secondary rainbow that appears about 10º farther from the  antisolar  point and twice wider with the colors inverted: red inside, violet outside.
              The rainbows are caused because the solar light is refracted and reflected inside spherical waterdrops.
              The primary rainbow has one internal reflection in the drop and, the secondary two reflections.



              The most famous Halo is  the " Ring " of the Sun and of the Moon. It is the 22º halo ,named for its radius,  is the most frequent and the brightest in any display.
              Dimmer and rarer is the 46º halo .
              There are many phenomena linked to the 22º.
              The most common feature is the strong color - red in its fine internal board and, bluish in its more diffuse external board.
              An observation common in the 22º halo is the Parhelion or sun-dogs, sometimes called mock suns. They are brilliant patches of light at the same altitude as the Sun, at 22º of each side of the last.
              They can be observed without the totality of the 22º halo .
              Several colors of the rainbow are observed, but here the refractive medium is ice, not water.