Visibility

Rainbows can be seen whenever there are water drops in the air and sunlight shining from behind a oerson at a low altitude.

The rainbow effect is also commonly seen near waterfalls or fountains.The effects can also be artificially created by dispersing water droplets into the air during a sunny day. Rarely,a moonbow,lunar rainbow or night-time rainbow,can be seen on strongly moonlit nights.As human visual preception for color is poor in low light,moonbows are often perceived to be white.It's difficult to photograph the complete arc of a rainbow,as this would require an angle of view of 84 degrees. From an aeroplane,one has the oppertunity to see the whole circle of the rainbow,with the planes shadow in the centre. This phenomenon can be confused with the glory,but a glory is usually much smaller,covering only 5-20 degrees.www.gymhol.cz/.../fyzika/03_disperze/Moonbow.jpg