I spent a good bit of last week checking on the NOAA GOES visible satellite loops to see if I could spot the Station Fire. I wasn’t able to, but I know it’s possible. The video below is from the University Corporation for Atmospheric Research, and it shows the 2007 fires in Baja very nicely. That image is supposed to be from GOES-West, which is the satellite that provides the visible, infrared, and water vapor imagery for the Western half of the US. The resolution looks a little better than what I’m used to seeing from the GOES satellites though, so I’m suspicious. Although it’s very obvious here that we’re looking a smoke and not clouds, the giveaway would be the point source for the smoke. Clouds won’t behave quite like that.
ChopperChick posted some more great photos from the Station Fire, but there were 2 particularly cool ones. On the left is the image from the Terra Satellite’s MODIS. Although the Terra Satellite is pretty awesome in it’s own right, it’s not very helpful from an aviation weather perspective. (It’s a useful tool for studying climactic change, and you can view the fire response imagery here.) Check out the 2 intense white splotches just left of the center of the image. Unlike the smoke trails cast off by most of the fires, there’s something different going on there. If you zoom in, you can see the thick, brown smoke at the base, and the white parts…those would be cumulus clouds. Specifically, pyrocumulus, and that’s what’s shown on the right.
I remember seeing these for the first time on the way out to do a stage check when I was finishing my private pilot ticket. This was right about the same time that the Salmon River fires were burning in the central mountains of Idaho (another MODIS image, below). Clear skies everywhere, except that over the mountains to the north, there were 2 massive cumulus clouds piling up. We even saw some lightning up in the tops of one of the clouds.
Like all cumulus clouds, pyrocumulus form because a moist air mass is lifted aloft and cools. In this case, the fire provides the lifting mechanism and the moisture comes (at least in part) from the burning vegetable matter. The weather around pyrocumulus clouds is also what you’d expect from cumulonimbus or towering cumulus: turbulence, updrafts, downdrafts, and IMC and icing in the cloud.