Glory in the field

Image by András Bali of Hungary.

Proof, if any be needed, that it is not necessary to be in an airplane or on a mountain slope to find a glory.

Here the droplets of a low lying morning mist have backscattered sunlight to produce the effect.

Essentials for the glory are sunlight shining through, or onto, mist and a clear view in the direction directly opposite the sun. To catch a glory in a level field like this the sun must therefore be low and shadows long.



The glory is one of the more enigmatic of atmospheric optics effects. Small droplets scatter, diffract, light backwards into the eye and camera. But the precise way that they do this is not at all straightforward. Rigorous mathematical theories predict it exactly but do not throw much light on the 'how'.

Light reflected once inside the drops - a classically impossible path! - is a large contribution. Other routes are via 10, 6 and 5 internal reflections. Surface waves help join up the impossible gaps in the ray paths. But we should not talk too strongly of ray paths in small droplets where the wavelength of light is a significant quantity.



Impossible ray.

Images ©András Bali


The dark shadow upwards from the glory centre is puzzling. It might be the result of a post behind the camera masking some of the sun's rays.

Atmospheric
Optics
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