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Dr Toner Stevenson

Parhelion - it's a sun dog!


Photograph by Kim Kemmis at Macquarie Park, late afternoon, 30 August, 2018.

It's very rare in Sydney to experience the icy, yet sunny, conditions and thin cirrus cloud that cause a spectacular halo around the Sun and a reflection of the Sun in the sky (at least once and often on either side of the sun in the line of the arc). Yesterday, my colleague Kim Kemmis captured the image above of the parhelion and parhelic circle on his way home from work (he was not driving). Earlier, at sunrise, Sydney City Skywatcher member Adriano Massatani captured the effect as seen below.

The term 'parhelion' describes the reflection of the Sun and 'parhelic circle' is the term for the icy arc which shows colours of the rainbow due to the refraction of light passing through the ice crystals in the cold cirrus clouds. You can find out more using this link and scrolling down to the article about Adriano's observations. There is no doubt that the weather is always a talking point.

The term 'sundog' is used because it is a 'fake ' Sun, and one type of halo in the taxonomy of halos. Perhaps it looks like the Sun is leading two smaller Suns as you might when walking a dog?

Photograph below by Adriano Massatani, northern beaches, sunrise, 30 August 2018

Adriano Massatani Ice Arc

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