I think it would be relevant to the raising or falling of the barometric pressure.And the direct perpendicularly arc free straight line to the equator.

Okay, Badger girl is technically correct if we are talking about a word with no gravity and only air resistance.

But since I do most of my bowhunting on EARTH, where we have both gravity AND air resistance, then I'm sticking with my assertion that both air resistance AND gravity affect the flight path of the arrow.

I'm thinking about this more and more.

Question...

"IF" we use a square with levelers (with bubbles)for plumb and level......HOW can the arrow not be parralel to level ground (on ahorizontal plane) AND the string not be "Plumb" to said ground (level ground)?

Does it have something to do with the arrow at full draw NOT being "level"? (v. the bow not being drawn)

During the equinox you would be exactly right.

Of course one must take meridian arc into this equation.

how could you still hunt earth, its got horrible LOCATION compared to mars.

I think you're thinking about this slightly backwards. The image posted here of the EYEtoPEEPtoSIGHTtoTARGET line is very deceiving.

The line of sight is quite simply, from your EYE to the TARGET. The peep and pin is aligned on that line to ensure your arrow intersects the line at the target. Thats why we have to sight in our bows for different yardages, because the arrow flys in a parabolic curve.

Consider how you anchor your bow. What you do is fix the relationship between your eye, and the nock/string intersection. (not exactly if you use a kisser button, but to close to notice a difference). You then rotate your bow up or down about that fixated point, that changes the angle of the arrow in relation to the line of sight.

I hope this helps...

Jeff, if your at full draw and aiming at a 20 yard target your arrow will not be level to earth, it will be point high/nock low. Your arrow does not leave the bow level when shooting at targets down range, remember the arch,

So if you draw a straight line from your nocking point, down your arrow that straight line would go straight over the target not intersect with it. (when at full draw).

Then how do you explain setting one up with a level and a square? If it's perpendicular/plumb to the string......it's Perpendicular/plumb to the ground. Ifyou're using a bubble level to set your arrow......what's it "level" to?

Also......This has nothing to do with the original question......but wouldn't the location of the target at 20 yds determine whther or not your arrow was "level" with the 20yd spot? Or....are you saying that ther eis nowhere you could put your target and have your arrow be "level"?

The arrows elevation on the bow at rest is set in readings that are 90 degrees to the string. The string however would not be perpendicular to the ground if you were shooting at a target 20 yards out shoulder high. The arrow would also not be parellel to the ground.