Home    OpticsPOD   What's New    Rays & Shadows   Water Droplets   Rainbows     Not a rainbow!     Primary Bow     Secondary Bow     A's Dark Band     Other Orders       3rd & 4th       5th & 6th        Zero Order Glow         Glow formation     Supernumeraries     Red Bows     Rainbow Wheel     Dew Bow     Sea Spray Bow     Glass Bead Bows     Reflection Bows     Twinned Bows     Cloud Bows     Moon Bows     Image Gallery     Simulators   Ice Halos   High Atmosphere   Links & Resources   Search - Index                   123456789012345678		Zero Order Glow
		Early evening rain shower. There were bright primary and secondary rainbows opposite the sun. Sunward, where fine rain was also falling, the sky was suffused by an intense orange. The sun was the same deep colour and had hazy blurred edges, the small inset image does not do it justice. The unusual glow was caused by sunlight passing through raindrops without any internal reflection. Image©2003 Les Cowley.        Next time there is a rainbow look at the sky towards the sun. If rain is falling between you and the sun there will likely be an intense glow. It is best seen when the sun is low and already orange or red. This extra glow, over and above the ordinary sky brightness in the sun's direction, is formed by light passing through the raindrops and emerging the other side without having been internally reflected. I call this the 'zero order glow' zero because the number of reflections involved is zero, glow because it is a diffuse light without the sharp intensity concentration of a rainbow's rim.