The researchers on Expedition to the Antarctic see beautiful halos with sundogs. Ice crystals in the atmosphere create these phantastic light phenomena.
Photo: Full halo with clear sun dogs and light pillar.
With air-temperatures around -20° Celcius, we observe fantastic light phenomena above the sea ice of the Weddell Sea. Beams of sunlight are broken and reflected in specific ways depending on shapes and angles of ice crystals in the atmosphere. The most common phenomenon is a rainbow like circle at an angle of 22° from the sun. Such rings are known as ‘halos’ derived from the old Greek word for a circular threshing floor. In the inner halo, under the right conditions, two so-called ‘sundogs’ are visible plus a light pillar above.
Only when the inner ring is strong, a second halo may be observed in an angle of 46° from the sun. And we could see it! To catch it all in a single picture one needs a stronger wide-angle lens on the camera than I have, so it had to be captured in half an image. The outer ring was much weaker and lacks the ‘dogs’ but ended as a weak rainbow in the sea ice.
This morning it became certain that I had to write a blog about this. The first view through my cabin window revealed a beautiful sunrise in a narrow clear band of sky between the sea ice horizon and a narrow band of clouds. It took me a while to realise I was viewing sunrise in triplicate! So I dashed outside to take a picture while shivering in the cold. I had to share such beauty. Although at this position of the sun there was no clear halo, the two sundogs were strongly present. What a fantastic view! Like this, even a one-track minded biologist can be totally dazzled by physical phenomena.
Jan Andries van Franeker
PS first successful SUIT hauls show krill and diversity of life under ice. More news later.