Engineering
When the Sky Fights Fire
Quick fact
Aerial firefighting aircraft deliver water or fire retardant to slow a wildfire's advance, not to extinguish it outright. The red mist often seen is a slurry of water, ammonium phosphate salts, and coloring agents that coat vegetation, reducing its flammability even after the water evaporates.
Why this is interesting
You've seen planes drop red clouds over wildfires, but what's really in that mist, and how do pilots know exactly where to aim when the ground is an inferno?