|Rays through raindrops ~
Steinar Midtskogen captured this 200° wide sunset panorama near Oslo, Norway. At left is a sunset reddened primary rainbow with a faint outer secondary. The broad orange glow in the sunward sky is, in part, the 'zero order glow' also from sun touched raindrops. See below for video.
©Steinar Midtskogen, shown with permission
|Zero Order Glow
Most sun rays pass through raindrops without making an internal reflection.
These rays have no minimum deviation angle and do not form a distant caustic sheet.
Instead of a rainbow there is a beautiful orange glow that suffuses the sky.
Whenever there is something spectacular in the sky check the opposite direction.
|Primary & secondary bows
are produced by sunlight reflecting once and twice inside near spherical raindrops.
The outgoing rays forming each bow cross one another and form a bright caustic sheet. The sheet is the outer edge of the primary bow and another sheet forms the secondary inner edge.