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 3.9 micron data from the GOES-16 East and GOES-18 West satellites on the January 2025 Southern California fires.
 We download the reprojected data from UW SSEC's [RealEarth program](https://realearth.ssec.wisc.edu/).
 Each image is 128x128 pixels, centered at (34.1, -118.4). Each pixel is 1.0 km.
-The fires sometimes disappear from view due to cloud cover.
+The satellites measure the temperatures of the topmost infrared-opaque region in the atmosphere, 
+which may exaggerate the extent of fires from heated smoke, or hide the extent from cloud cover.
+You can see how quickly the fires initially grow — up to a square mile every minute at first — fueled by dry vegetation and strong winds. 
+This shows the extreme difficulty of containment.
 
 The code combines the two satellites' data for increased resolution.
 It currently measures the areas of hotspots.