Although they are incredibly common, you may sometimes not even notice that they are there. You may be staring at the sky, the sun directly over you, and you may not even notice the halo right above your head. It could be because, on that day, the halo was white and didn’t resemble a circular rainbow. None the less, there is a halo over your head and either you’re an angel, being warned of the apocalypse, or are witnessing an amazing optical and scientific phenomenon: halos. Halos are beautiful rings of light that form around the sun or moon, depending on the time of day. Even though we know so much about halos, some people think that they are signs of the apocalypse. It’s strange how such a simple creation can cause such a stir, as it did when a place in Mexico saw a sun halo. Some people even get to witness different types of halos, and there are countless different types. Halos are both scientific and optical phenomena, and it’s no mystery why. Seeing one is amazing and baffling, but the science behind them is even more of both.The creation of halos is a lot simpler than you may have imagined. It starts up in the troposphere, which is the lowest level of the atmosphere, where there are many ice crystals. In fact, there are too many to count. The ice crystals that come in many different shapes and sizes and are all oriented in different ways. These ice crystals take sunlight or moonlight and refract or bend it. This refraction and the orientation of the ice crystals leads to a circle of light being created around the sun, moon or source of light. However, different types of ice crystals and their orientation can easily create a whole new type of halo (see “TYPES OF HALOS” for more). Appart from the classic white halo, halos can come in all sorts of colours, that is why some refer to them as circular rainbows. The beautiful colours are a byproduct of dispersion. On occasion, as the white light passes through the ice crystals it not only refracts the light but also disperses it giving it colours. It is most common for the inside edge of the halo to be red and the outside to be blue. The only thing is that the blue edge is less saturated than the red. Sometimes you can get a colourful halo and other times you can just get a simple white one. But you still whiteness beauty no matter what.Ice crystals, the main component in the creation of all types of halos, are formed in the troposphere and come in many different shapes and sizes. As an example, the 22° halo, a very simple type of halo (see “TYPES OF HALOS” for more), is created with tiny hexagonal ice crystals. More on these hexagonal ice crystals, they can ace viewed as part of an equilateral 60° prism. Now apart from their differences in shape and size, they all are oriented differently. The shift in orientation can easily change the type of halo. The crystals can be very strange at times. On cold days where the weather is below 0°, the ice crystals begin to slowly float downwards from the troposphere. Don’t get this concept mixed up with snow. Snow is made of multiple tiny ice crystals while these falling crystals are all separate. Anyways, even though the crystals are now falling, they still refract light. This is because as they fall, they start acting like prisms. As they fall, the light they refract can change one type of halo to another (see “TYPES OF HALOS” for more). Ice crystals usually have the basal plane or base plane facing parallel to the ground and it even stays parallel as it floats to the ground.Like previously mentioned, there are many different types of halos. Some are caused by differently shaped ice crystals and some are created by differently oriented ice crystals. Nonetheless, there multiple different types of halos, some incredibly complex and some incredibly simple. The most common kind of halo is called the 22° halo. It’s the smallest type of halo and very simple. It’s just a circle of light surrounding the sun. But, there is a reason it is called a 22° halo. The ice crystals used for 22° halos are made of are hexagonal are very tiny. When these crystals refract the sunlight, they create the circle around the sun like a normal halo would, but the original ray of sunlight and the refracted ray of sunlight meet at a 22° angel. This halo can still come in colours, with red edge once again being more saturated than the blue and they still form around either the sun or moon. These halos are an exact copy of normal halos, they just have a small detail that makes them different. Other kinds of halos are not as common such as sundogs. Sundogs are normal 22° halos with intense spots of light on the sides or top. There is usually 2 spots of light but there can be more. These spots of light are added to halos on cold days. They are formed from ice crystals that are falling from the sky and are oriented differently from all the others. As mentioned earlier, when ice crystals fall from the sky, the act like a prism and continue to refract light. The intense spots are a byproduct of this. No matter what colour the halo is or what type it is, nonetheless, a wonderful sight to see.