Well-Known Member
Nov 3, 2008
I have a question with regards refraction with large objects close to the line of sight.

I have a hilly location where I wish to shoot out to about 1500 yards, but there is a hill located about half way to the target area. The top of this hill will be very close to the line of sight to where the target will be located.

Can this cause any sighting error due to refraction? Has anyone ever experienced this?


Well-Known Member
Jan 20, 2004
Blackfoot, Idaho
Interesting question.......

I would suspect that is you would focus your scope on the tip top of that hill you will be able to more clearly see the mirage at that point. Then focus at the 1500 yard distance with the same point of aim. That should tell you something.

I would suppose that watching the mirage would reveal what the wind is doing on that hill. There may be more wind deflection, as in updrafts than refraction.

To my favorite long range target area (rocks) its a 4 hour walk, round trip, from the shooting spot. Thus I've set no wind flags. But there is no hill in the middle.

There are considerable up drafts when the wind is blowing, at any speed, as the mountain faces directly into the prevailing winds. There are small canyons parallel to the wind which funnel wind up and I've noticed that when shooting at the top of a canyon vs not, I have to reduce the elevation adjustment to compensate from shooting a 100 yds away from that wind funnel.

Good luck.