Barometric Pressure? Altitude?

[engineer40]

I bought a wind meter / anemometer recently. The marketing material says it gives me Wind Speed, Temp, Station Pressure, Barometric Pressure, Altitude, and Density Altitude. Sweet, I think that's all I'll need for a ballistics calculator.

I became disappointed when I read through the directions and you need to know either the barometric pressure OR your altitude from an external source.

After spending some more time reading it seems like this may be common and all anemometers need outside data input? Is that really the case?

Thank you.

 

[Greyfox]

I bought a wind meter / anemometer recently. The marketing material says it gives me Wind Speed, Temp, Station Pressure, Barometric Pressure, Altitude, and Density Altitude. Sweet, I think that's all I'll need for a ballistics calculator.

I became disappointed when I read through the directions and you need to know either the barometric pressure OR your altitude from an external source.

After spending some more time reading it seems like this may be common and all anemometers need outside data input? Is that really the case?

Thank you.

My G7 rangefinder which has density/altitude does not require calibration. The ballistic outputs match exactly those using my Kestral/Shooter system.

 

[Carpe Beerem]

Can you set the baro pressure first and then set the altitude to zero? That might trick it to giving you station pressure.

 

[Michael Eichele]

I set my altitude to zero feet. Then it gives me the real pressure at my location regardless of my altitude. Then I set my ballistic calculator altitude field to zero feet and input the station pressure into the pressure field.

 

[engineer40]

My G7 rangefinder which has density/altitude does not require calibration. The ballistic outputs match exactly those using my Kestral/Shooter system.

Thanks Greyfox! Hopefully a G7 is in my future at some point.

 

[engineer40]

Can you set the baro pressure first and then set the altitude to zero? That might trick it to giving you station pressure.

I can. But then I still need to know my real baro pressure first correct? And I would need to get that from an outside data source.

Is that common? What is the best way to know the real barometric pressure when you are in the field?

I set my altitude to zero feet. Then it gives me the real pressure at my location regardless of my altitude. Then I set my ballistic calculator altitude field to zero feet and input the station pressure into the pressure field.

Thanks Michael.
That almost sounds too easy. The instructions for my anemometer definitely state that I need to know either my altitude or barometric pressure and calibrate the device first. Then it says after I do that I can set my altitude to 0ft and it will display my Station Pressure.


Thanks for the replies. I am definitely interested in knowing how to work my device better. But the other half of this post is so I understand the atmospheric conditions better regardless of which anemometer or ballistics software I am using. Thanks again!

 

[TexSavage]

40, do you have a GPS unit that will give you the altitude you are at, enter that, and then it should calibrate. Curious as to the unit you purchased, I have had some of the same confusion and I am curious if what I have done is correct. I normally reset my elevation based on what my GPS says at where I am hunting and that elevation changes less than 200 feet per location, so the effect is very small moving from one place to another. Hope this thread produces some information that's helpful to many of us that have some confusion.

 

[engineer40]

40, do you have a GPS unit that will give you the altitude you are at, enter that, and then it should calibrate. Curious as to the unit you purchased, I have had some of the same confusion and I am curious if what I have done is correct. I normally reset my elevation based on what my GPS says at where I am hunting and that elevation changes less than 200 feet per location, so the effect is very small moving from one place to another. Hope this thread produces some information that's helpful to many of us that have some confusion.

While researching this, purchasing a GPS to find my true altitude is the direction I keep thinking I'll need to go. However I don't know if barometric pressure and altitude are so directly related that if I input my true altitude will the device be able to give me my true barometric pressure or is it just an educated guess?

When I say "my device" it is a Caldwell Crosswind Professional Wind Meter. But I'm also asking to learn more about how these devices work in general. Like if I had a Kestral, would I also need to calibrate it?

Am I making a mountain out of a mole hill with this stuff?

It seems like I read and read... and depending on what website I'm on, the verbiage people are using seems to contradict itself.

Thanks all.

 

[cohunter14]

One cheap (free) thing you could do is just download the Trimble GPS Hunt app on your smartphone. It will show you exactly where you are on a topo map, which would give you the altitude. The cool thing about the app is that it works even if you don't have cell service. Just make sure you view the map of the area where you are hunting before you lose service and it will have it pre-loaded onto your phone. Heck of a lot cheaper than buying a GPS!

The other thing to keep in mind is that you can probably pre-load the altitude into the wind meter ahead of time, so you don't have to do it while prepping for a shot. Assuming you are not varying by thousands of feet in a given day, that should work just fine.

 

[geo4061]

The Kestrel comes from the factory set to give you and use station pressure for it's shooting solution. You can change the settings. This will give you altitude and barometric. Just be sure to change it back to station pressure when you want a shooting solution.

 

[Michael Eichele]

If you know you're at 5128' elevation and set your meter with that, the meter will give you pressure corrected to sea level. You then have to enter that into your calculator along with altitude. If you want to simplify, set your altitude to zero. Then it will always give you station pressure which is all you ever need.

 

[Bravo 4]

40, do as Michael says and just use station pressure and leave the altitude at zero.
These devices (unlike GPS) use the pressure to determine altitude. At the mountain warfare school we used a device the worked on pressure and every time we made it to a point on the map that was surveyed to a certain altitude we had to recalibrate it for that altitude. Pain in the butt! Plus the pressure can change throughout the day and when fronts move in and out, this will change the altitude on such devices where you are at even though you never moved. So simplify it and use station pressure.

Also the idea of using a Topo phone app is a good one. I use one and now hardly ever use a GPS.

 

[engineer40]

I set my altitude to zero feet. Then it gives me the real pressure at my location regardless of my altitude. Then I set my ballistic calculator altitude field to zero feet and input the station pressure into the pressure field.

If you know you're at 5128' elevation and set your meter with that, the meter will give you pressure corrected to sea level. You then have to enter that into your calculator along with altitude. If you want to simplify, set your altitude to zero. Then it will always give you station pressure which is all you ever need.

You were absolutely correct Michael. It only took me another 5-6 hours of reading to figure it out. I kept getting confused because the instructions of the device talk you through calibrating the device from either known Baro Pressure or known Altitude BEFORE setting the Altitude to 0ft so it gives you the Station Pressure. Which just like you said, Station Pressure is what you want anyways.

At the end of the day, the solution was so incredibly easy I can't believe I read about it and couldn't figure it out for so long.

Just go into Pressure calibration mode and set the Altitude to 0ft and the device outputs the Station Pressure. You don't need to calibrate anything.

I won't need to calibrate it because I don't actually care about my Altitude or the Barometric Pressure. I only care about and will use the Station Pressure (Absolute Pressure) in the ballistics software.

I'm sure this confuses many people who purchase this device. Their instructions are horrible.

 

[engineer40]

You were absolutely correct Michael. It only took me another 5-6 hours of reading to figure it out. I kept getting confused because the instructions of the device talk you through calibrating the device from either known Baro Pressure or known Altitude BEFORE setting the Altitude to 0ft so it gives you the Station Pressure. Which just like you said, Station Pressure is what you want anyways.

At the end of the day, the solution was so incredibly easy I can't believe I read about it and couldn't figure it out for so long.

Just go into Pressure calibration mode and set the Altitude to 0ft and the device outputs the Station Pressure. You don't need to calibrate anything.

I won't need to calibrate it because I don't actually care about my Altitude or the Barometric Pressure. I only care about and will use the Station Pressure (Absolute Pressure) in the ballistics software.

I'm sure this confuses many people who purchase this device. Their instructions are horrible.

OK, I take back everything I just said. Finally after weeks of emailing Caldwell's customer support (4 times now), they just responded to me. They said the Station Pressure is just an estimate. The only 2 things the meter actually measures are wind speed and temperature.

Ironic that I noticed the verbiage on their Amazon add also changed within the last week and they took some of their marketing claims down. But if you go to their actual website they still make all of the false claims.


So let me ask you guys this. If I set my Altitude to 0ft and I'm driving down the road and go up a large hill the Station Pressure definitely changes like you expect it to. If I go down a hill then the station pressure changes the opposite way just like you expect. How is it doing that if it's not actually measuring pressure?