I've seen people build tunnels or chutes like PP said, too. I've also seen little roof extensions with little walls coming right around off the pop door. You could build something like that, but put it at an angle with a little deck under it. Or just make it coming off to the side of the coop (instead of straight out) and then your ramp coming up to it. So build a little square "room" right off your pop door with enough room for your chickens to get around it and just make the opening along the side of your coop instead of straight on-- that should deter the wind. I'd put a little roof on it- doesn't have to cover the entire thing. Think of it as an enclosed porch-- just change the entrance to the side or put it at an angle. Whatever you think will work best. I hope that makes sense, but I think your problem is easily fixable!