The other day Betty Meredith posted a stunning photo on my Facebook page. That’s not unusual; Betty has an amazing eye for photography.
A question accompanied the photo. Betty wanted to know what the soft vertical band of colour was in the middle of the picture she took last week in Mahone Bay, N.S. Betty went on to say the photo was taken just after sunrise on a very cold morning.
Immediately I thought sundog!
Sundogs look like tiny sections of rainbows but there is one significant difference – the temperature. Rainbows are formed by sunlight striking liquid raindrops and sundogs come from sunlight striking clouds made of ice crystals that form in the upper levels of the atmosphere. Their scientific name is “parhelia” (“parhelion” for one).
Sundogs can and do occur at any time of the year, but they are most common in the winter when the sun is low in the sky and ice crystals fill the air.
Sundogs can be a sign of foul weather; since the cirrus and cirrostratus clouds that cause them can signify an approaching weather system, sundogs can signal the arrival of rain or snow within the next 24 hours.
The day Betty saw the sundogs at the coast; there was an offshore system, but it didn’t bring any wet weather ashore.
To be sure that this was indeed a photo of a sundog, I asked Betty if the sun was on the left of the streak of light. She confirmed that it was, and I knew then we were dealing with a sundog. The colour nearest the sun is always red.
I’m not sure why we refer to parhelia as sundogs, but some say it’s because they appear to “sit” beside the sun like a loyal dog by his or her owner.
I love the imagery and the photo!
- Read more Weather University columns.
- Have a weather question, photo or drawing to share with Cindy Day? Email email@example.com
Cindy Day is the chief meteorologist for SaltWire Network.