Water vapor and minute bits of dust, salt and clay-silicate particles swirl about in the mixture. The atmosphere has four vertical layers that radiate from Earth and vary by temperature and composition. Proceeding from the ground outward, they are the troposphere, stratosphere, mesosphere and thermosphere. All of the optical phenomena halos, sun dogs, sun pillars, coronas and rainbows are produced at specific levels in the troposphere, which extends from the surface up to about 12 kilometers, eight miles or 42,000 feet depending on which measuring stick you pick. Here, the temperature decreases rapidly with altitude averaging 59 F at the surface and a right chilly -69 F at 11 km.
Commercial jets fly in the upper reaches of the troposphere.
High-level cirrus clouds form in extremely cold air where water vapor condenses on tiny dust and salt particles to form ice crystals. The crystals can randomly float in a cloud or can fall in layered groups as the shapes interact with air currents and fall through the troposphere. The colors trapped in white light Halos, sundogs and sun pillars are produced when light passes through or reflects off hexagonal plates or columns. Each hexagonal ice crystal acts like a tiny prism. When white light from the sun or moon passes through the crystals, it bends or refracts.