photo #8287535

It wasn’t the red traffic lights that stopped Alexia Major (Cloud Appreciation Society Member 61,450) as she drove home in Dartmouth, Nova Scotia, Canada, but the prismatic lights of a parhelion in the Cirrus high above the junction.A parhelion, or sun dog, is created when sunlight is refracted through hexagonal crystals of ice that act like tiny prisms. These flat crystals gently drift downwards in the cloud, with their hexagonal faces horizontal, like falling autumn leaves. The bright patch of sunlight forms as the rays shine in and out through vertical sides of the hexagonal plates of ice, and so sun dogs appear level with the Sun, off to one or other side of it. Alexia also spotted a fragment of another optical effect, known as a parhelic circle, which can appear as a horizontal white line emanating from the parhelion. ‘I exclaimed with joy!’ she told us, ‘But don’t worry, I safely pulled into the nearest side street to take my photos.’