Have you ever looked up at the sky and noticed a circular ring of light around the Sun or Moon? This beautiful and captivating sight is known as a 22° halo, a fascinating atmospheric phenomenon that can tell us a lot about the conditions high up in the Earth’s atmosphere. In this blog, we’ll explore what a 22° halo is and what it signifies.
What is a 22° Halo?
A 22° halo is an optical phenomenon that belongs to the family of ice crystal halos. It appears as a circular ring with a radius of approximately 22 degrees around the Sun or Moon. Contrary to what one might think, the 22° halo is not located at a specific distance from us, but is a visual effect created by light interacting with ice crystals in the atmosphere.
The name “22° halo” refers to the radius of the ring, which is roughly 22 degrees from the center of the light source (either the Sun or the Moon). The inner edge of the halo is usually sharper and more colorful, while the outer edge is more diffuse and faint.
How is a 22° Halo Formed?
The formation of a 22° halo is a fascinating process involving light and ice. This phenomenon occurs high up in the Earth’s atmosphere, in the cirrus or cirrostratus clouds. These clouds are composed of tiny, hexagonal ice crystals.
When sunlight or moonlight passes through these ice crystals, it’s refracted, or bent, at an angle of approximately 22 degrees before reaching our eyes. This refraction results in a circular halo around the Sun or Moon. The size of the halo is determined by the refractive index of ice and the geometry of the ice crystals.
What Does a 22° Halo Mean?
Seeing a 22° halo can indeed tell us something about the weather. As mentioned earlier, a 22° halo occurs in the presence of high, thin clouds made of ice crystals. These cirrus or cirrostratus clouds often precede a warm front, indicating that weather conditions may change. In many cases, the appearance of a 22° halo could suggest that rain is on the way within the next 24 to 48 hours.
However, it’s important to note that while a 22° halo can indicate an approaching weather system, it doesn’t guarantee a significant change. Other factors and observations should be taken into account when predicting the weather.
A 22° halo is a beautiful and captivating atmospheric phenomenon that results from the interaction of light with ice crystals in the atmosphere. While it’s a stunning sight to behold, it also serves as a reminder of the incredible processes occurring in our atmosphere and can be a useful tool in understanding and predicting weather patterns. So, the next time you spot a halo around the Sun or Moon, take a moment to admire it and consider the intricate interplay of light and ice crystals that makes it possible.