Shooting against the thermals

A

andyd1179

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I have seen a number of threads about shooting in the wind which is not my problem, as I feel confident in this area. I have just come back from the World Championships that were held in Milan, Italy were I was able to shoot shoulder to shoulder with DJ, David and Craig which are great guys. The biggest problem I had was shooting in the thermals. Here in the UK, this is something that we don’t have. But I would like to have an understanding on how to read the thermals. I guess that this can only be done by what you see the through the scope.
When the flags dropped I would take the shot but the round would go high into the eight, this would be due to the thermals.
The question is what should I be looking for to get the round to go were I want it to go when there are thermals and what should I be looking for through the scope?
Any help much appreciated, AndyD UKBR22
 
Good question Andy. Not sure anyone knows the real answer.
I find it's best to shoot when the wind is rising/increasing and not falling/decreasing.
Fred K
 
Re-Fred Message

I thought it might be a hard question to answer but when your up against the clock and the thermals are playing around with you, it's no fun. but i thought someone might have looked at this area in some detail as i guess in the USA this is something that might come up on a regular basis.

thanks Fred
 
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Flags and Tails dead calm then a thermal is not your problem.
However it could be temperature gradients that are causing some of your problems.
With that being said I would guess that temperature gradients at the Championships would be a minor player and I would look else where.
 
Andy:

We don't have much of a problem with thermals (mirage) in my part of our country. We're right up against the Canadian border. But, I've shot down in Louisiana and South Texas, so know something thermals bending light waves.

The rule is: Never shoot in a boil. That is when the mirage is bubbling straight up. The image that you see during a boil is higher than where the target actually is. A shoot then, of course will go high: (Unless you aim low)

Wait until the mirage is running in agreement with your wind flags. And, be aware that the image you now see is displaced in the direction the wind is blowing. To me the best thing about mirage is that it is a rough indicator of wind speed. It goes away when the wind is above 7 MPH.

Joe Haller :)
 
Re-Joe message

thanks Joe, its an interesting area that i have never seen covered in a topic. So I guess when you see the ripple effect above were you wan to shoot then it's better so shoot low. I know that if you have the time then wait for the wind to come back but thats not always possible when your against the clock, which is what happen to me at the WBC. I guess also the quality of the optics come into this as well as they would show different events happening maybe.

thanks for your comment Joe, be interesting to see if anyone has ideas on this. Cheers, Andy
 
Thermal & Mirage are not the same.
If you shoot a shot and return to battery and not 12:00 on the 8 ring then it is not Mirage unless your scope is sighted in to hit at 12:00 on the 8 ring?
Example: I am going across a target holding at 4:00 on the ten ring for a wind that is blowing from 2:00 at 4 mph. After each shot when I return to battery my crosshairs are were they were before the shot. Then the wind stops. I now move my cross hairs to the x and shoot. If my shot goes high on the 8 ring than it is not Thermals or Mirage that put it there!
It is Equipment (including ammo) or Shooter. Could be a temp gradient but that would be rare in this example.
 
re-last

Getting slightly confuse and i am sure that it was thermals that were the problem at WBC. Its ashame DJ, Craig and David dont come in this one as they would be able to tell you it was. i can understand what both you are saying but its two different ideas on two different things maybe Joe can expand on this a bit.

Andy
 
Take a few minutes to read about Mirage:
http://en.wikipedia.org/wiki/Mirage#Cause
Then try Thermal.
http://en.wikipedia.org/wiki/Thermal
(Apples and Oranges)

These are not in depth But Do provide some insight on your questions.

Next see what might apply to your situation.
This is not Rocket Science!
Both are related to shooting the “Conditions”,
Now with that being said forget thermal but do understand that Mirage is ever present.
One thing I would like to mention is that if you think you can just aim a little low when you think a Mirage is playing havoc with your score then you might want to reevaluate your understanding on what it takes to shoot in the “Conditions”.
The Wind is Not Your Friend! And I think I am done ‘Beating this dead horse’.
 
I stand corrected . . .

A thermal is a column of rising air.

A mirage or light refraction is caused by light passing through areas or layers of cold and warm air.

So by definition, my explanation was wrong.

As the sun heats the ground on the range, the heat rises.

As light from the target passes through the air to our eye, it bends as it goes through areas of different temperatures.

So, mirage is a visible indicator of thermal air movement.

In a previous century when I was shooting prone smallbore matches, we would set our spotting scopes a little out of focus so we could see the mirage half way down range, rather than at the target, where thermals and the resulting mirage would have no effect on bullet drift.

Joe :)
 
Andy,

What power scope are you using?? I didn’t see much mirage through my 45x and compared to here I’d call Italy very mild.

Look at the fullbore (long range prone) side of things, they need to deal with it a lot more than us and in the past I’ve see some good articles explaining the mechanics of it.

Peter
 
Mirage or Thermal

Andy,

I had a chat to your team mate Carl Boswell about this in Milan after unlimited 50 meters (& he beat both of us). He said that he could see the waves through his scope & as they were rising from say left to right upwards he would aim low & left & the shot would move up in the same direction as thermals? Not sure what DJ & co were doing but they were also doing something right, maybe when DJ comes over to the UK for training this can be one of the things he teaches you guys..Let us know if you find the answer :rolleyes:
 
Re last two messages

Glad you guys came on this thread a i thought i was asking a silly question:confused:
the scope I have Peter is a Nikko 10x50x60 and it did seem show you a mirage or thermals happaning when the wind died which normally i would aim and hit what i wanted to hit, but in Milan this did not happen so just trying to get a better understaing of this area. we would never get anything like this in the UK, just dont have the weather for it! but would like to know how technically how to deal with such things and i think Doug and Joe imput has helped a bit. But i guess it is going to be a case of wait for the wind or take a chance in conditions like that.

Andy
 
Fred K said:
Good question Andy. Not sure anyone knows the real answer.
I find it's best to shoot when the wind is rising/increasing and not falling/decreasing.
Fred K
Click to expand...


That's strange, all the Creedmoor shooters I know prefer exactly the reverse. Is this common among the .22 bench crowd? Is there even a rule of thumb for this?

Brent

PS. Thermals do not, in my opinion, blow your bullet upwards so much as the heat waves (diffraction of light, aka mirage) creates an illusion of where the bullet is and that makes you shoot high. You are aiming where the bulls-eye ain't.
 
Exactly the reverse . . .

I have read a few statements on this board that said,"never shoot in a let-up". Well: It seemed right to me. I have always tried to shoot when the tails of my flags were at the same angle and steady.

Been using one of Gene Biggs Wind Probes for the past three years, and ONE wind flag. Last year I deceided to try "shooting in a "let-up", because that wind probe gives such a clear indication of the let-up. I touch the shot off just before the "dixie cups" reach the center mark.

I found it works good for me. Now I am one of those rare rimfire benchrest shooters who "Shoot in a Let-Up".

Joe :)
 
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