What is the Halo Around the Sun or Moon?

Sometimes when you look up in the sky you may see what appears to be a circle around the sun or moon.  This is what people call a halo around the sun or moon.

Seeing a halo around the sun or moon, similar to seeing a rainbow, does not happen very often and feels special when you see it.  You never know when you are going to see it and you never know how long it is going to last.  I have heard stories or rumors about that a halo around the sun means that a storm is on the way.  I wonder if that is true?

halo around sunWhat Causes a Halo Around the Sun or Moon?

Halos form around the sun or moon for the same reasons.  It occurs when there are high, thin clouds (so high, and thin that you can hardly notice them; it may even appear that the sky is practically clear) in the sky.  These specific type of clouds are called cirrus clouds – they form at over 20,000 feet up in the sky and are made up of tiny ice crystals.  They look like thin, wispy strands of clouds that often point in the direction the wind is moving.

A halo forms when these high cirrus clouds are in front of the sun.  The ice crystals in the clouds reflect and refract the sunlight which causes a halo to appear around the sun.

What Does a Halo Around the Sun or Moon Mean?

There is an old weather saying that says, ‘ring around the moon means rain soon’.  This is not always true, but often is.  A halo around the sun or moon means that there are high cirrus clouds, which may be followed by a storm in one or a few days.  However, this is not always followed by rain or a storm.  It may simply be the case that there are some high cirrus clouds, but no storm is coming.

If you want a more technical explanation of this phenomenon then check out the weather channel.