Sure thing, let’s keep it tight. Air pressure and humidity change the density of the air. Higher density means the bullet faces more drag, so it slows down more and falls a bit sooner. Roughly, a 1% increase in air density can drop the range by about 1–2 %. Humidity adds moisture to the air, which makes it slightly lighter, so a high‑humidity day can give you a small lift—maybe a centimeter or two on a long shot. The trick is to use the standard drag coefficient for the bullet and plug in the local air density: ρ = P/(R T) – that’s how you turn those numbers into a precise range correction.