There's also a standard humidity level of 78% and a barometric pressure of 29.53 inches, but those have a far smaller effect than elevation and temperature.
Is it really possible to distinguish altitude and barometric pressure effects?
Altitude is often estimated from relative air pressure is it not?
Granted temperature tends to fall with altitude and so might humidity (humidity is often relative humidity and measured with a "sling") so air density has many inputs on a given day. Then too there are gravity effects with distance from a center of mass but aren't those trivial, even for big gun naval gun fire, for external ballistics? Weather reports and such are usually reported as sea level equivalent to be useful across a reporting area.
What effect, apart from barometric pressure, might elevation that is altitude by itself have?
