Jumping sundogs: A weird weather phenomenon
If you’ve ever seen what appear to be three bright Suns lined up neatly on the horizon, then you’ve probably witnessed sundogs. This rare phenomenon occurs when hexagonal ice crystals in the air align to refract sunlight into your eye at a precise angle. This forms a halo of light around the Sun, with two bright patches on either side of it called parhelia, or sundogs.
Even rarer are jumping sundogs, which occur when lightning discharge in a thundercloud temporarily changes the electric field above it. This adjusts the orientation of the ice crystals so that they refract the sunlight differently, making the sundogs move around as if they’re jumping.
As they need ice crystals to form, sundogs usually only appear during cold weather and when the Sun is low in the sky. However, they have been spotted from several different locations around the world. It’s not just the Sun either, as light from the Moon can generate Moon halos and moondogs in much the same way.
Discover more amazing natural wonders in the latest issue of How It Works. It’s available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, make sure you subscribe today!