Science > Physics > Adjusting Pressure Reading at Airport to My Elevation
| Topic: |
Science > Physics |
| User: |
"W. Watson" |
| Date: |
29 Mar 2007 02:18:26 PM |
| Object: |
Adjusting Pressure Reading at Airport to My Elevation |
Is there a simple way to compute my air pressure at 2700' to the reading
from the airport at 3100'?
--
Wayne Watson (Nevada City, CA)
Web Page: <home.earthlink.net/~mtnviews>
.
|
|
| User: "Greg Neill" |
|
| Title: Re: Adjusting Pressure Reading at Airport to My Elevation |
29 Mar 2007 02:48:46 PM |
|
|
"W. Watson" <wolf_tracks@invalid.com> wrote in message
news:6iUOh.4125$Kd3.143@newssvr27.news.prodigy.net...
Is there a simple way to compute my air pressure at 2700' to the reading
from the airport at 3100'?
This might help:
Pa = Air pressure at airport
ha = Elevation at airport in feet
Ph = Pressure at desired height
hh = Elevation at desired height in feet
k = 3.616 x 10^-5 ft^-1 is a constant that depends to some extent
upon air temperature, but may be constant
enough depending upon your required
precision.
Then
Ph = Pa*exp(-k*(hh - ha))
.
|
|
|
|
| User: "Mike Fontenot" |
|
| Title: Re: Adjusting Pressure Reading at Airport to My Elevation |
29 Mar 2007 04:06:20 PM |
|
|
"W. Watson" wrote:
Is there a simple way to compute my air pressure at 2700' to the reading
from the airport at 3100'?
I asked (and answered this question) quite a few years ago, when I was
an active pilot and needed the answer for reasons (now forgotten)
related to flying. It was so long ago that I don't remember the
answer. But as I recall, it requires assuming that there are no
"dynamics" (i.e., unsteady air motion) involved, and some assumption
about the variation of temperature with altitude. Pilots use
this relationship (unconsciously) when they read their altimeter to
determine their altitude, after obtaining an "altimeter setting" (via
radio communication) from someone on the ground. That person on the
ground merely adjusts his own
altimeter to read his (known) elevation, and then reads the (calculated)
sea-level pressure on a little window in the altimeter. Again, that
calculation assumes a specific variation of temperature with altitude.
The pilot then dials that same sea-level pressure reading into his own
altimeter. Ordinarily, this procedure is accurate enough to keep pilots
from running into any terrain, but it CAN be significantly in error when
the actual temperature variation with altitude is extremely unusual.
(For the more routine use of altimeters to provide separation between
aircraft assigned to different altitudes, this effect doesn't cause a
problem, since all the aircraft at (approximately) the same location
will have the same error due to the temperature variation).
Mike Fontenot
.
|
|
|
|
| User: "Sam Wormley" |
|
| Title: Re: Adjusting Pressure Reading at Airport to My Elevation |
29 Mar 2007 03:25:47 PM |
|
|
W. Watson wrote:
Is there a simple way to compute my air pressure at 2700' to the reading
from the airport at 3100'?
Is not the pressure reported by any airport adjusted as if it was
at mean sea level (MSL)?
.
|
|
|
| User: "" |
|
| Title: Re: Adjusting Pressure Reading at Airport to My Elevation |
29 Mar 2007 04:15:02 PM |
|
|
Sam Wormley <swormley1@mchsi.com> wrote:
W. Watson wrote:
Is there a simple way to compute my air pressure at 2700' to the reading
from the airport at 3100'?
Is not the pressure reported by any airport adjusted as if it was
at mean sea level (MSL)?
Yes, it is.
--
Jim Pennino
Remove .spam.sux to reply.
.
|
|
|
|
|
|
Related Articles |
Intriguing Reading
Ed Witten Seen Reading Lee Smolin's "The Trouble With Physics": NSF Quadruples LQG's Funding, Slashes ST's Funding, and Every University Gets Three LQG Theorists To Talk Amongst Themselves & Give One Another Tenure!
Reading Aristotle- De Generatione et Corruptione
Suggested Reading: Berlinski, "Newton's Gift", Simon & Schuster, (2000)
Re: Top 10 things I've learned reading sci.phys
Worth reading
Reading Aristotle
Structure and Interpretation of Classical Mechanics -- reading group
| Reading Aristotle- Analytica Priora
Ed Witten was seen reading Woit's THE NOT EVEN WRONG while simultaneuosly walking down Nassau Street in an inertial frame, followed by his 137 postdocs, who were chanting in unison, as measured by a stationy observer standing outside of PJ's Pancakes
New: mind reading computers
Reading for turbulent supefluid ether people
Re: Top 10 things I've learned reading sci.phys
What we know, future scientist will ever know, our limitations, an article worth reading even if it don't help you :-)
Re: Top 10 things I've learned reading sci.phys
|
|
|
