TLDR; If you ever see a halo around the sun or moon get indoors quickly. This almost always means a storm is coming.
Have you ever seen a circle of light or halo around the sun or moon? Well, sun and moon halos are unusual sights that have left many alarmed and wondering whether they could mean rain or storm is coming.
According to the weather folklore, seeing a ring around the moon or sun could indicate that rain or storm is coming. Halos come in a wide range of forms, including white rings, colored rings, arcs, and even spots in the sky. The most popular halo is the circular halo, which is also known as the 22 degrees halo. Other types of halo include the light pillar and sun dog.
Another fact about halos is that they only happen in Polar Regions as well in countries that experience icy winters. They usually occur during winter or summer, and their frequency depends on the occurrence of cirrus coverage. This can also depend on whether the place has had a history of halo forming crystals.
What Causes Halos Around the Sun or Moon?
More often than not, halos around the sun or moon are usually caused when a thin layer of cirrus or cirrostratus clouds moves across the sky. Cirrus clouds are very high clouds, approximately 20, 000 feet high above us, which are made up of tiny ice crystals.
The high clouds are a result of a change in air pressure. In cold weather, the cirrus clouds can float near the ground, and it is known as diamond dust.
Although cirrus clouds do not cause storms or rain, they usually come a day or two before low-pressure events. This is why they are known for bringing precipitation storms. They are the first layer of clouds to be seen when the periphery of the storm system draws near.
Cirrus clouds are typically brought about by ice crystals high the atmosphere. However, it is crucial to understand that thin cirrus clouds that produce a ring can also appear without any associated storm system or weather change. For instance, they may be brought by fine particles in the sky. When this happens, precipitation may not occur, and the halo may an unreliable sign of a storm or rain coming.
Sun and Moon Halos
During the day, the cirrus passes in front of the sun, and halo is formed when the light refracts through the ice crystals. Passing of the sunlight through the ice crystals results in splitting of light into colors as a result of dispersion. The crystals reflect and refract light, and this causes the formation of a ring or halo.
Other times, the thin layer of cirrus can also pass across the moon at night, and this creates a similar effect. As the cirrus cloud passes in front of the moon or sun, the icy crystals refract light, and this forms the halo.
The next time you see the icy clouds refracting light around the sun or moon, know that this could be an indication of cirrus clouds. This would be suggesting that a storm is a day or two away, and it would best to get indoors.