From candy-cane snow rollers to fragile flowers, ice can take on magical, complex guises. Here are six that might catch your eye this winter
Sun dogs
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You aren’t seeing triple. Sun dogs, brightly coloured blobs of light sometimes visible on either side of the sun (pictured above), are really mirror images of our star.
They appear when it is cold enough for tiny ice crystals to be present in the atmosphere. The illusion is the result of sunlight bending or refracting through these floating crystals, which act as prisms. Consequently, sun dogs are rainbow-hued: the inner edges, closer to the sun, are tinged with shades of red, while the outer edges are blue. They belong to a group of optical phenomena called halos, which all involve sunlight interacting with ice crystals.
Sun dogs are officially called parhelia. Their more common name derives from their appearing to follow the sun, like a dog follows its master. The best time to try to spot them is when the sun is close to the horizon, around sunrise or sunset.
Frost flowers
Henri Koskinen/Alamy
A truly rare sight, these beautiful but short-lived ice sculptures form when the sap inside plants freezes. This can happen when the air temperature is freezing, but the ground is not yet frozen. The sap inside long-stemmed plants expands in the cold, creating cracks in the stem. Now water can ooze out and freeze, forming intricate and fragile ribbons or flower-like structures (pictured above).
Snow rollers
Nature and Science/Alamy
As big as an oil barrel or as small and fragile as a stick of candyfloss, snow rollers (pictured above) form on windy hillsides when strong gusts blow moist snow along the ground. “You get a chunk of …
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