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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Altitude vs. Barometric pressure
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<blockquote data-quote="Mikecr" data-source="post: 74112" data-attributes="member: 1521"><p>Thats right. </p><p>Say your nearest weather report calls for sunny skies, 80deg, with a barometric pressure(not station) of 30.55, and the wooden Tikki outside the diner you just ate at had 4000ft carved on it.</p><p>Your internally calculated pressure alt for 4000' is 25.84 and you have an resultant RO of .830. But being really sunny &amp; nice out, pressure is actually alittle higher. </p><p>30.55-29.92= 0.63"hg higher.</p><p></p><p>With this correction of .63 entered and added to std pressure at altitude you get 26.47 and apply it to reach actual air density as though it were absolute pressure and altitude had been set to zero. Result is Ro=.850</p><p>This higher Ro follows a new/adjusted pressure altitude of 3,353' if calculated in reverse. Again, due to the pressure being high today.</p><p></p><p>That's all internal though, as the hunter just entered 80deg, 4000ft, and .63" of pressure correction from std(if using altitude and barometric pressure -29.92).</p><p>Your program figured out std pressure at altitude and added a pressure correction as though at sea level. Then, using this new pressure continued it's air density calcs.</p><p></p><p>How this would be interfaced is totally beyond me. But it would prevent human error, as you have locked them out of setting pressure if using altitude, but still allowing a correction to it as appropriate.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 74112, member: 1521"] Thats right. Say your nearest weather report calls for sunny skies, 80deg, with a barometric pressure(not station) of 30.55, and the wooden Tikki outside the diner you just ate at had 4000ft carved on it. Your internally calculated pressure alt for 4000' is 25.84 and you have an resultant RO of .830. But being really sunny & nice out, pressure is actually alittle higher. 30.55-29.92= 0.63"hg higher. With this correction of .63 entered and added to std pressure at altitude you get 26.47 and apply it to reach actual air density as though it were absolute pressure and altitude had been set to zero. Result is Ro=.850 This higher Ro follows a new/adjusted pressure altitude of 3,353' if calculated in reverse. Again, due to the pressure being high today. That's all internal though, as the hunter just entered 80deg, 4000ft, and .63" of pressure correction from std(if using altitude and barometric pressure -29.92). Your program figured out std pressure at altitude and added a pressure correction as though at sea level. Then, using this new pressure continued it's air density calcs. How this would be interfaced is totally beyond me. But it would prevent human error, as you have locked them out of setting pressure if using altitude, but still allowing a correction to it as appropriate. [/QUOTE]
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Altitude vs. Barometric pressure
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