Lunar Halo

This is one of the more peculiar sights one can see during stargazing. The first time I saw this, I swore I was imagining it, but when others saw it as well, I felt relieved. What am I speaking of? Well, a lunar halo of course!

In weather lore, these heavenly rings were taken as a sign of impending bad weather. Now, this is supported by scientific evidence. The lunar halo is formed by refraction of light off of ice in the atmosphere. This ice is the very thin, wispy cirrus clouds. These clouds are so high in the atmosphere they almost exclusively exist as ice. Cirrus clouds often precede rainy or snowy weather.

The light from the moon refracts off of the very thin ice of the cirrus cloud, it is bent to precisely 22 degrees. This bend is what makes the circle in the sky. This halo is formed in almost an identical fashion as a rainbow is. Lunar halos are more common in the winter months as the cold temperatures result in more icy clouds.

The next time you see one and think about how this night time rainbow is formed, also think about an umbrella in the next few days.