An optical phenomenon called the 22° halo or winter halo was seen over Peterborough tonight, seemingly signalling oncoming cold weather.
A 22° halo belongs to the family of ice crystal halos. It forms as the moonlight is refracted in millions of hexagonal ice crystals suspended in the atmosphere.
In folklore, moon rings are said to warn of approaching storms. Like other ice halos, 22° halos appear when the sky is covered by thin cirrus or cirrostratus clouds that often come a few days before a large storm front.
However, the same clouds can also occur without any associated weather change, making a 22° halo unreliable as a sign of bad weather.