What is Density Altitude?
The concept of 'density altitude' is kind of like the concept of 'wind chill'.
Stick with me here, I'm going somewhere with this.
Cold weather is dangerous for the human body, and wind (because of increased heat loss on human skin) makes it worse. But how much worse? Is it worse to be outside in -10C temperatures with a 20 knot wind, or -15C temperatures with a 12 knot wind? The concept of 'wind chill' resolves those two values into a single easy number.
Density altitude works the same way. It's difficult and tedious to compare and contrast how an airplane will perform on a 25C day with a pressure of 29.80 at an elevation of 600 MSL, versus a 20C day with a pressure of 30.17 at an elevation of 1250 MSL. We need a way to mash all of these variables into one easy-to-use number. That number is density altitude.
So just as I can say &quot;The wind chill is -10C&quot; and it doesn't matter whether it's warm but windy or cold and calm, I can say &quot;The density altitude is 2,000&quot; and everyone will have the same idea of the expected performance of the airplane, no matter what combination of factors led to that result.
Once you start thinking of (and using!) density altitude as a simplification tool, its value becomes a lot more obvious.