I you’re hunting into the wind, the dog runs a across it “windshield wiper” style. This covers the most ground w/ his nose & least with his legs. If the wind is blowing across your beat (a cross wind), the dog punches out & back more or less. Again he’s running perpendicular to the wind thus maximizing his efficiency. Most dogs figure this out on their own with experience.
Many handlers think the dog should run “windshield wiper” regardless of the wind but think about it, if the dog is running straight into the wind (cross wind), the only scent he’ll find is what’s directly in front of him. If he then turns & runs with the wind, he can’t smell anything w/ his tail so that whole cast is wasted effort.
Generally speaking, you want your dog to run perpendicular to the wind as much as possible. This maximizes the amount of ground he covers w/ his nose for each step. Make sense?