Observation by Peter Tickner: Unusual Solar Arc

Uploaded by

Peter Tickner

Observer

Peter Tickner

Observed

2020 Feb 18 - 11:13

Uploaded

2020 Feb 21 - 00:19

Objects

The Sun

Equipment

Apple iPhone 11 Pro Max

Location

Urban Berkshire

Target name

Unusual reversed colour arc in a contrail above the Sun

Title

Unusual Solar Arc

About this image

I was standing outside my observatory in the garden when I noticed this unusual effect high above the Sun apparently in a contrail. It doesn't seem to match the common effects such as Sun Dogs or irridescence in clouds near the Sun. The colours are reversed to a Circumhorizonal effect and above not below the Sun. If it doesn't have a name for now I am calling it Tickner's Anticircumhorizonal arc!

Files associated with this observation

Sun Dog Feb18baa.jpg (1.7 MB)

Like this image

Jeremy Shears, David Basey, Dr Paul Leyland, Mr Leonard Entwisle, Martin Lewis, Peter Meadows, Miguel Araújo, Honor Wheeler, Andy Wilson, Lyn Smith, Andrew Dumbleton

Comments

Peter Meadows, 2020 Feb 21 - 21:18 UTC

Nice photo - I think it is a Circumzenithal Arc (see https://www.atoptics.co.uk/halo/cza.htm) which have the same colour order as in the photo.

Peter Tickner, 2020 Feb 21 - 23:11 UTC

I did consider that but everything I've checked says that only happens below - not above - the Sun.

Peter

Peter Tickner, 2020 Feb 24 - 17:04 UTC

On further research I think that this is a partial Supralateral arc. They are usually brightly coloured, above at approximately the height of a circumzenithal arc and often mistaken for them, but circumzenithal tend to have much paler colours.

Peter

Honor Wheeler, 2020 Feb 24 - 22:21 UTC

Having imaged many atmospheric optics over the years, this is indeed a partial Circumzenithal arc, 'zenithal' meaning seen above your zenith i.e. the point above your head. CZ's are always seen above the Sun were as a circumhorizontal arc is always seen below the Sun. Quite often aircraft contrails create the same size ice crystals to give this strong concentrated colour. A supralateral arc doesn't have such an intense colour, they are a weaker form and are rarely seen in the UK.

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