Sundogs over Geelong, March 2000

Dogs of the Day

Clyve Herbert


Twin sun dogs shine over Geelong – March 2000.  Both left and right show comet style tails.

It was one of those miserable anticyclonic days – nothing was expected to happen, although I have yet to see a day in all of my life that something didn’t happen (the ‘joy threshold principle’!!) I noticed after midday, way off to the west, the faint outline of a cirrus band.   Progressively during the afternoon the cirrus band moved closer, carried along by a rather feeble 300hPa flow. Watching the cirrus kept me occupied while I hacked away at (pruned) the apple tree.  I had already made a mess of the crabapple!  Time for a cup of tea I thought – I think of cups of tea every 30 minutes, much to the disgust of my good wife.  But I’ve always been a plodder, and I enjoy a non-organised day after an extended period of work.  With the taste of my chocolate digestives still on my tongue, I ventured outside to deal with the apple tree.   The cirrus band meanwhile had encroached almost overhead, but the sun was yet to go behind it.  I often look at cirrus and wonder what it would be like to stand among the crystals.  I forgot about the apple tree and just looked as the cirrus gradually moved closer with the sun becoming increasingly absorbed by the opaque ice.  I disappeared into the garden shed to get a better clipper, or one I thought would do the job easier.  In that time (barely several minutes), the sky was transformed.  I looked up and saw almost unbelievably, twin mock suns shining down, and again, another day has given me a pleasant surprise.  I have occasionally seen one sun dog, but never two. I’ve seen photographs and descriptions, but here they were in real life.  I raced inside, grabbed the camera and my wife, and the children to show them this rare display of nature.  My wife was impressed!  My children thought they were UFOs and raced off to tell their friends, probably never to forget for the rest of their lives, because I certainly won’t. 

The best explanation for mock suns can be found in R Scorer’s “Clouds of the World” (1972 – p149).  Mr Scorer’s description and analysis of everything to do with clouds is remarkable.  If you can get hold of a copy in a secondhand shop, buy it!…but back to the explanation…….”the sun dog forms on the brightest part of the parhelic circle”.  “It is apparent that this type of reflection occurs in the presence of randomly and vertically oriented crystals whose axes are perpendicular to the line from the observer to the sun.”