A 22-degree circular halo spotted today, caused by sunlight refracting through ice crystals in the thin cloud layer.

A bright ring surrounds the sun, which is blocked by an overhanging street sign.

A full 22-degree circular halo spotted today, caused by sunlight refracting through ice crystals in the thin cloud layer. (It was around 65F at ground level.)

These halos are about the same width as a 1x photo on my phone (and most point-and-shoot cameras I’ve had), so I used the wide angle mode to catch the whole thing and then crop it down. I bumped up the saturation a little, but otherwise it’s unprocessed.

A bright circle in the sky surrounds the silhouette of a stop sign blocking the sun. Below it, a bike path winds into the distance and electrical towers stretch upward.

A bright circle in the sky surrounds the silhouette of a stop sign blocking the sun. Below it, a bike path winds into the distance and electrical towers stretch upward.

It turns out having a wide angle lens on your phone is really helpful for catching sun halos!

Update: Someone on Flickr blamed this effect on aircraft emissions. No, these have been around long before aircraft. They’re caused by light refracting through ice crystals, which can be near the surface or high in the upper atmosphere. They get even more elaborate in places where it’s colder near the surface and more ice crystals can be suspended in the air – diamond dust in places where people are skiing, for instance – and super-elaborate in places like the arctic and Antarctica, which can support lots of ice crystals (and the south pole doesn’t have a lot of airplanes flying over it). More info: Atmospheric Optics: Ice Halos

There haven’t exactly been a lot of airplanes flying around here over the last few weeks, either – including the day I took this photo.

A bright sundog next to a glass-sided building.

A bright sundog next to a glass-sided building. The sun is off to the left out of frame. The sundog had a bit more color and more of the spectrum in it as seen through my polarized sunglasses, so I kind of wish I’d taken a shot through one of the lenses, but at least you can see how bright it was.

I haven’t adjusted the color on this image at all -– except for cropping, it’s straight out of my phone.