I’m coming around to the idea that the grains of moisture is more impactful on horsepower than the DA number. I have run good mph for the car at 3200 feet DA, but dry air and been disappointed at 400-500 DA with damp air. Cloudless sky is hard to beat. Thinking logically, the increase in air pressure from 100 feet to 3000 is relatively small. The increase in volume due to temperature is relatively small. Going from 10% humidity to 80% is huge.
Wet air can be compensated for with timing. The biggest thing that will affect a naturally aspirated car is barometric pressure. As actual altitude goes up barometers go down. Also storm fronts can have a great affect on ACTUAL barometer readings. Not what you get on TV weather which is ALWAYS a corrected barometer reading. This is a big factor in calculating DA's. For instance where Brad runs his car the barometer is usually high 29's to over 30. Out here where I am we do back flips if the baro reading reaches 28.00! Why NHRA factors altitiude tracks and changes indexes for the various classes. Those only adjust for the physical altitude not the weather.
