Atmospheric
Optics
Halos & How to spot them
Images by Matt Hoskins in Berkshire, England on 16th January.
" While cleaning my car yesterday I noticed an odd rainbow effect in the paintwork and quickly realised it was actually the reflection of an ice halo above me. I rushed inside and grabbed my camera and took a few shots."
Images ©Matt Hoskins
A colour subtraction enhancement reveals a well shaped upper tangent arc and above it a faint upper suncave Parry arc.
Britain's skies are not renowned for halos but they are there if you care to search.
Keep the car bonnet clean!
Reflection from a dark (preferably convex) surface is a good way to spot halos, iridescent clouds or a corona. The glare is reduced, the view 'concentrated' and the head is at a more comfortable angle (we are not well evolved for halo observation). Sunglasses are helpful too. Shield the sun behind a pole or building.
The bright halo at left is the high overhead circumzenithal arc. Touching it and curving rightwards is a supralateral arc.
Scroll down for more halos of that day.
Below: Both paintwork and windscreen show halos.
