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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: 74087" data-attributes="member: 1521"><p>Well let's look at it carefully. </p><p>Say altitude is checked. Pressure disappears. You enter actual altitude, and the program uses a std pressure for that altitude in it's calcs.</p><p>What if actual pressure is higher or lower than std at that altitude? How you gonna enter that deviation? </p><p>In order to calc air density correctly you'd have to determine and enter "pressure altitude" from a CALIBRATED Krestel. I guess GPS(for actual altitude) would be best for calibrating a Krestel while observing absolute pressure from a source known to be correct.</p><p>It just seems weird and confusing.</p><p></p><p>Anyone using actual altitude from GPS or maps would likely observe corrected pressure as reported locally that day. That pressure would often be near 29.92"hg regardless of altitude, and if different(say 28.7"), there needs to be a way for them to enter this. Maybe in the form of a correction like -1.22"hg. This, to be applied to Std pressure at altitude, for the day.</p><p>It's not something I would use, but that or pressure altitude are the only ways I can picture using altitude instead of absolute pressure.</p><p>Just thought I'd throw that out there.</p></blockquote><p></p>
[QUOTE="Mikecr, post: 74087, member: 1521"] Well let's look at it carefully. Say altitude is checked. Pressure disappears. You enter actual altitude, and the program uses a std pressure for that altitude in it's calcs. What if actual pressure is higher or lower than std at that altitude? How you gonna enter that deviation? In order to calc air density correctly you'd have to determine and enter "pressure altitude" from a CALIBRATED Krestel. I guess GPS(for actual altitude) would be best for calibrating a Krestel while observing absolute pressure from a source known to be correct. It just seems weird and confusing. Anyone using actual altitude from GPS or maps would likely observe corrected pressure as reported locally that day. That pressure would often be near 29.92"hg regardless of altitude, and if different(say 28.7"), there needs to be a way for them to enter this. Maybe in the form of a correction like -1.22"hg. This, to be applied to Std pressure at altitude, for the day. It's not something I would use, but that or pressure altitude are the only ways I can picture using altitude instead of absolute pressure. Just thought I'd throw that out there. [/QUOTE]
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Rifles, Reloading, Optics, Equipment
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Altitude vs. Barometric pressure
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