Now, in the map menu, click on “Vertically Integrated Smoke.” Instead of measuring smoke around 8 meters off the ground, it’s modeling what a 25-kilometer-high column of air looks like in a given place in the US. (Think of it as the smoke that you can see in the sky, versus the near surface smoke being the stuff you’re actually breathing.) As you can see, on this scale, smoke now covers most of the country.
To map this out, HRRR considers the infrared intensity of those fires and projects how much smoke a fire is producing. That smoke starts off in the eddies of what atmospheric scientists call the boundary layer. “It’s the layer through which you feel the bumps when you land in an airplane in the late afternoon anywhere in the country,” says Benjamin. “But then some of that air gets mixed further up above the boundary layer,