Barometric Pressure on Shooter App

[Zeke-BE]

So all I know is using elevation/ temp and plugging that in and use the reading after that! Reading other places they are suggesting only barometric pressure. Some stuff is not clear to me on my app. If I plug that in does it affect what I already have with elevation that is plugged in or do I hit 0 and put in barometric pressure??

Any advise or help would be great!!!

[dse]

If you check pressure is absolute then it cancels out the other information. I use the reading from my 1600B and has been spot on.

[lancetkenyon]

DSE nailed it. I use actual barometric pressure readings from my 1600B &/or Kestrel.

[300RUM]

This might help explain how barometric pressure is used and the differences in ways that barometric is measured and / or reported. It is from the directions to Applied Ballistics, another ballistics application.

 

 

Atmospheric inputs have historically been the least understood and caused the most trouble for shooters running ballistics programs, in particular the pressure inputs. The following discussion elaborates on the correct way to manage these variables. Basically there are two options for describing pressure to a ballistics program; 1) Enter the barometric (aka corrected) pressure and altitude, or 2) Enter the Station pressure where you are. Some definitions are in order regarding barometric and station pressure.
Barometric pressure is also known as sea level corrected pressure, and is what the weather station and airports report because it's useful for pilots and making weather assessments. Barometric pressure is not the actual air pressure where you are, rather it's a number that's corrected to sea level. In order to determine the actual air pressure where you are (which is what the ballistics program cares about), you have to account for the effects of altitude. However if you have a handheld weather meter like a Kestrel, you can measure Station Pressure directly which is the actual air pressure where you are. This is the preferred method of inputting pressure data because it's one less input and relies on only one measurement instead of two.
A common error is to mistake station pressure for barometric or vice versa. The consequence of this error is that the wrong air density gets applied which degrades the accuracy of trajectory predictions. This error is increasingly more severe the higher up you are above sea level.
Refer to the image on the right for proper set-up of the atmospheric pressure inputs. Note the reference altitude is set to 0 ft in the Kestrel which indicates it's displaying uncorrected station pressure, and the Pressure is Absolute box is checked in the program indicating it's using station pressure.

To further clarify the output from the Kestrel, here is an excerpt from the Kestrel user's manual:

"Some final notes - If you wish to know the actual or station pressure for your location (such as for engine tuning), simply set the reference altitude on the BARO screen to “0”. In this case, the Kestrel Meter will not make any adjustment and will display the measured value. (Engine tuning and ballistics software sometimes refer to atmospheric or station pressure as “absolute pressure.” These applications are concerned with the actual air density, as opposed to pressure gradients relating to weather, so barometric pressure is less useful."

[Zeke-BE]

So what about printing off cheat sheets to tape on your rifle for quick glances. Since your not there to get an accurate reading I always look at google earth and find out my hunting elevation and plug that in for a quick cheat sheet. Does that sound right?? I understand when you have a long shot, and angel lets say 20 degrees you better make sure everything in your app is correct.

[Big Browns]

If your only shooting out to 500 yards your paper should be close enough. When you are shooting 500-1000 yards you will definitely need to have a more accurate system if you want to consistently make one shot kills!

[DesertBull]

IPhone 6 and newer has a built in barometer

[Zeke-BE]

If your only shooting out to 500 yards your paper should be close enough. When you are shooting 500-1000 yards you will definitely need to have a more accurate system if you want to consistently make one shot kills!

 

Agreed!! If its farther than that you should have time to set up and log everything in. You don't want to rush a 700 yard shot.

[300RUM]

These days I have Applied Ballistics on my phone. It can use the phone to measure angle to target. A kestrel feeds environmental data by bluetooth and I have a laser range finder. It is all very handy and if all the data is entered correctly, very accurate. I still print a trajectory card for every hunt. Technology is great but if you depend on it something as simple as a dead battery will ruin your day. My scopes have MIL calibrated reticles and the rifles have ACI's mounted on them. I carry a set of cards that give me trajectory and wind compensation, data for ranging with the MIL reticle, tips for estimating wind, etc.