If you've caught a sunrise or sunset in Minnesota over the past couple days, you might have noticed a red, hazy view.
The reason – as is usually the case – is fire.
The National Weather Service Twin Cities said fires in Idaho, Montana and the British Columbia area are creating smoke. And those smoke plumes are drifting east, covering parts of the northern Midwest.
Here's a map the service posted:
You can see the source of the fires, and which areas are the smokiest. For example, western North Dakota has "heavy" coverage, while Minnesota is either "medium" or "light."
Why does smoke make a sunrise or sunset look red?
This blog post from Cliff Mass has a good explanation. Basically, the smoke particles break up the wavelengths of the sun's light. This tends to disperse the shorter purple and blue wavelengths, more than the longer red-orange ones.