Mirage and wind

[Sisco]

Saw this on a web page. You distance and desert shooters: Thoughts and opinions? Valid or not?

[Matt.Cross]

Yeah, I'd say that's pretty accurate...

[Sisco]

Thanks Matt. 

[98Z5V]

Very valid.  Very useful, too.  That's what we primarily use to check wind between shooting position and target. 

If you're seeing mirage, and it disappears, (either the wind just completely died, or) it's over 12 mph.  Winds above 12 wash the mirage right out.  If that happens, you read it at an angle from your target.

Measure mirage at a 45-degree angle (away from target), determine the wind speed, multiply by 1.4. 

Measure mirage at a 60-degree angle (away from target), determine the wind speed, multiply by 2.0.

Edited March 30, 2018 by 98Z5V

[Armed Eye Doc]

3 minutes ago, 98Z5V said:

Very valid.  Very useful, too.  That's what we primarily use to check wind between shooting position and target. 

If you're seeing mirage, and it disappears, (either the wind just completely died, or) it's over 12 mph.  Winds above 12 wash the mirage right out.  If that happens, you read it at an angle from your target.

Measure mirage at a 45-degree angle (away from target), determine the wind speed, multiply by 1.4. 

Measure mirage at a 60-degree angle (away from target), determine the wind speed, multiply by 2.0.

That sounds like trigonometry to me.

[edgecrusher]

1 hour ago, Armed Eye Doc said:

That sounds like trigonometry to me.

Good thing I close my eyes when I shoot!

[Rsquared]

35 minutes ago, edgecrusher said:

Good thing I close my eyes when I shoot!

You too? I thought that I was alone on that island.

[98Z5V]

5 hours ago, Armed Eye Doc said:

That sounds like trigonometry to me.

We'll get into that shiit on the High Angle days.  Field expedient ways to determine angle to target, using Angle Degree Indicators/Angle Cosine Indicators mounted to a rifle, and cheating...  We'll straight CHEAT with the laser range finder. It computes that shiit for us...  

[98Z5V]

At the Spring Shoot, the angle we were shooting down was 9 degrees.  Didn't make too much of a difference.  While Matt and JB Matt were sighting in, I hiked up further, and got an angle downward of 14 degrees - that was something to need to account for.  I also found a good place to shoot from,  so I brought them halfway up - from where they were to where I scouted the steeper angle.

The biggest problem was that we had the target pretty far from the base of the hill - that changed the angle.  We get it close to the hill base, and it'll be steeper, with more need to account for that.

Brush up on your Pythagorean theorem, because that's exactly what you'll need to solve this problem, and put rounds on target.

[98Z5V]

It won't turn into Trig until we're accounting for bullet flight time over distance, and the Earth's rotation...  THAT shiit is DEEP!  That's Coriolis Effect.

Great visualization of it, shooting west, then shooting east.

We will be shooting almost due west, during the Fall Shoot Long Range day.

Edited March 30, 2018 by 98Z5V