Scottish Glory tracked by Chris Brown between Aberdeen and Sunburgh in the Shetland Islands. ©Chris Brown shown with permission


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Find a seat on the side of the aircraft opposite the sun.     Search the clouds where the shadow of the aircraft would be – the antisolar point.     The glory is a delicate shimmering pattern of concentric coloured rings that drifts along the clouds with the airplane sometimes shrinking or swelling as it does so.

It is a diffraction pattern produced by light interacting with small cloud droplets and being scattered almost directly backwards.    
Not all cloud decks produce glories.   Almost monosized droplets produce the best with a dim central glow surrounded by rings tapering off in brightness.    

At left is a Mie theory simulation of glories computed by IRIS.    One half is for monosized droplets, the other for a droplets with a 20% (standard deviation) spread around the mean diameter of the population.  

A range of drop sizes smear away the glory structure because the diffraction pattern is drop size dependent – smaller drops give large glories and vica-versa.

Lower: Depending on height above the cloud deck the aircraft shadow is not always visible. Here the craft approaches the clouds as it descends into the Shetland Isles.   The glory surrounds the position of the camera rather than the aircraft.
Right: The inner glory structure of a weak central glow surrounded by a brighter ring blue on the inside and red outside.