Geometric vs. Barometric Altitude - Revision history

WikiSysop at 02:09, 23 January 2024

2024-01-23T02:09:31Z

2018-05-21T23:43:55Z

2018-05-21T23:28:18Z

2018-05-21T23:13:25Z

Created page with "http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/"

New page

http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/

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 Barometric altitude measurement relies on a "standard" atmospheric model. However, in practice there are many factors which affect atmospheric pressure. As skydivers, we see this all the time when we zero our altimeter in the morning, but by the afternoon it is a few hundred feet off. Because of this, a barometric altitude measurement rarely agrees perfectly with a geometric measurement. The following article discusses these differences in detail, and includes some real-world measurements which tell us how big the difference can be:
-[http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/ GPS versus Barometric Altitude: The Definitive Answer]
+[https://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/ GPS versus Barometric Altitude: The Definitive Answer]
 The bottom line is that geometric and barometric measurements can commonly differ by 5-10%. For skydivers, this means that at a geometric altitude of 10,000 feet, your barometric altimeter might read 9,500 feet. That is, when your FlySight tells you you're at 10,000 feet, you may look at your altimeter and see an altitude of 9,500 feet. This is perfectly normal.

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 ==Geometric Measurement==
-Geometric altitude measurement is typically performed using GPS, although there are other methods which would give the same result. A geometric altitude measurement tells you exactly how far you are from the ground. This is the measurement you would expect to get if you had a very long ruler.
+Geometric altitude measurement is typically performed using GPS, although there are other methods which would give the same result. A geometric altitude measurement tells you exactly how far you are from the ground. This is the measurement you would expect to get if you had a very long ruler. In practice, making geometric altitude measurements requires specialized electronic equipment like a GPS.
 ==Barometric Measurement==
-In barometric altitude measurement, we start with a measurement of air pressure.
+As we increase our altitude, atmospheric pressure decreases. We can plot this change as follows:
-http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/
+[[File:Pressure_vs_Altitude.png|center|500px]]

← Older revision		Revision as of 23:28, 21 May 2018
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		+	There are two main ways of determining altitude: geometric measurement and barometric measurement.
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		+	==Geometric Measurement==
		+
		+	Geometric altitude measurement is typically performed using GPS, although there are other methods which would give the same result. A geometric altitude measurement tells you exactly how far you are from the ground. This is the measurement you would expect to get if you had a very long ruler.
		+
		+	==Barometric Measurement==
		+
		+	In barometric altitude measurement, we start with a measurement of air pressure.
		+
	http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/		http://www.xcmag.com/2011/07/gps-versus-barometric-altitude-the-definitive-answer/