What Causes Halos Around The Sun Or Moon?


Halos around the sun or moon are fascinating optical phenomena that are caused by the interaction of sunlight or moonlight with ice crystals in the atmosphere. These halos appear as bright rings or arcs around the celestial body and are often accompanied by a variety of other optical effects.

Ice Crystal Formation

When high-altitude clouds contain a large number of ice crystals, such as cirrus clouds, the light from the sun or moon is refracted and reflected through these crystals, creating the halo effect. The shape and orientation of the ice crystals play a crucial role in determining the specific appearance of the halo. These ice crystals act as prisms, bending and dispersing light to create the intricate halo patterns that we observe in the sky. The complexity of the halo formations can vary depending on the size, shape, and alignment of the ice crystals present in the atmosphere. Atmospheric conditions, such as temperature and humidity, also influence the formation of these ice crystals, further contributing to the diversity of halo patterns seen in the sky.

Types of Halos

There are several different types of halos that can occur, each with its unique characteristics. Common halos include the 22-degree halo, which forms a ring at a 22-degree angle around the sun or moon, and the sun dog, which appears as bright spots on either side of the sun. Another type of halo is the circumhorizontal arc, which forms a colorful band parallel to the horizon. The variety of halo types is a result of the specific conditions in the atmosphere and the interactions between light and ice crystals. Observing and identifying these different halo types can offer insights into the atmospheric conditions at play during their formation and provide a deeper appreciation for the complexity of optical phenomena in the sky.

Optical Phenomena

In addition to halos, other optical phenomena such as sun pillars, light pillars, and iridescence can also be observed in the sky. Sun pillars appear as vertical shafts of light extending from the sun, while light pillars create a similar effect with artificial light sources on the ground. Iridescence, on the other hand, presents as vibrant, shifting colors in clouds or other atmospheric elements. These effects are all caused by the interaction of light with atmospheric particles, including ice crystals, water droplets, and dust particles. Understanding the various optical phenomena in the sky provides valuable insights into the physics of light and atmospheric dynamics, enhancing our appreciation for the natural wonders that surround us.

Scientific Explanation

Halos around the sun or moon are not supernatural occurrences but are rather the result of well-understood principles of optics and meteorology. By studying the behavior of light in the atmosphere and the properties of atmospheric particles, scientists can accurately predict and explain the formation of halos and other optical phenomena. Through scientific research and observation, meteorologists and atmospheric scientists have developed models to simulate the complex interactions that give rise to these optical effects. These models help elucidate the intricate processes occurring in the atmosphere and contribute to our understanding of how light behaves under different atmospheric conditions. The scientific explanation behind halos and other optical phenomena highlights the beauty of nature’s precision and the elegance of the physical laws governing our world.


Next time you see a halo around the sun or moon, take a moment to appreciate the beauty of this natural optical phenomenon and remember the fascinating science behind it. The intricate dance of light and ice crystals in the atmosphere creates a spectacle that captivates our senses and ignites our curiosity about the natural world. By delving into the scientific principles that underpin these phenomena, we gain a deeper understanding of the wonders that unfold above us daily. Let the sight of a halo serve as a reminder of the interconnectedness of light, atmosphere, and Earth, providing a glimpse into the captivating complexities of the natural world.

Nate Douglas

Nate has worked as a nutritionist for over 14 years. He holds a Master's Degree in dietetics from the University of Texas. His passions include working out, traveling and podcasting.