As an avid sky-watcher, I’m always on the lookout for unusual and captivating atmospheric phenomena. One of my favourite spectacles to witness are sundogs – those vibrant, shimmering apparitions that can appear beside the sun on a crisp, clear day. Also known as parhelions, these colourful optical illusions are caused by the refraction of sunlight through ice crystals suspended high in cirrus clouds.
Sundogs are created when sunlight is bent by the hexagonal ice crystals drifting in cirrus clouds. These ice crystals act like tiny prisms, refracting the sunlight and creating the illusion of duplicate suns. The resulting sundogs typically appear about 22 degrees to the left and right of the sun, and can persist for hours if the atmospheric conditions are right.
What makes sundogs so mesmerising is their sheer vibrancy and the way they seem to pulse and shimmer. The ice crystals responsible for this optical effect are oriented in a precise manner, with their faces perpendicular to the direction of the sun. As the sunlight passes through the crystals, it is bent and dispersed, creating the characteristic rainbow-like bands of colour.
Sundogs are but one example of the many captivating optical phenomena that occur in our skies. From sun dogs and sun pillars to halos and rainbows, the atmosphere is truly a never-ending source of wonder and delight for sky enthusiasts. The next time you spot those colourful, luminous spots flanking the sun, take a moment to marvel at the intricate dance of light, ice, and air that produces this dazzling celestial display.
