skycoach 0 #1 March 24, 2003 Just had a Tandem student ask me the following question and I do not have an answer: How much does the barometric pressure change per thousand feet. We do know there are variables like temperature and humdity but is there an average.[email]Allen.Flynn@EmersonProcess.com and Bob.Albers@EmersonProcess.com Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #2 March 24, 2003 THIS should do ya ____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
quade 4 #3 March 24, 2003 The basic rule of thumb is that a 1000 foot altitude change equalls a change in pressure by about 1 inch of mercury. This is close enough for jazz in almost any application up to about 18,000 MSL -- the point at which there is about 1/2 the sea level pressure.quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
quade 4 #4 March 24, 2003 QuoteTHIS should do ya Accurate though it may be, that chart gives -ME- a headache. It took me a couple of seconds just to figure out that the LOWEST altitudes were at the TOP of the chart. yeacch! Who the heck laid out that thing?!?quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
darkwing 5 #5 March 24, 2003 it is an exponential law... P = Po exp(-mgy/kT) where Po = the pressure at ground level m = the average mass of an "air" molecule g = acceleration due to gravity y = height k=Boltzman's constant T = temperature All in SI units of course... -- Jeff My Skydiving History Quote Share this post Link to post Share on other sites
SkydiveMonkey 0 #6 March 24, 2003 Guess it's cos the pressure is highest. I'm guessing this wasn't desgined for skydivers ____________________ Say no to subliminal messages Quote Share this post Link to post Share on other sites
quade 4 #7 March 24, 2003 Quote P = Po exp(-mgy/kT) Oh yeah, that's exactly what I'd say to a tandem student. On the other hand . . . a student or commercial pilot might actually get an answer like that out of me if he wanted more detail than the simple rule of thumb I gave earlier. The rule of thumb works well enough to get you through checkrides and most FAA tests.quade - The World's Most Boring Skydiver Quote Share this post Link to post Share on other sites
airgord 1 #8 March 25, 2003 My flight instructor used to tell me "high to low, look out below" not really pertinent to the post but I just felt like throwing it out. Cheers. Quote Share this post Link to post Share on other sites
