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Topic: Pressure altitude

Related Topics

Standard atmosphere

Density altitude

Standard conditions for temperature and pressure

Flight level

Atmospheric pressure

Altimeter

Pressure

International Standard Atmosphere

Density of air

Barometric formula

Pressure system

Altitude

Bar (unit)

Mean sea level

Airspeed

	Altitude and altimeters
		The movement of the pressure sensing capsule is transferred and magnified, via a mechanical linkage or piezo-quartz component, to a dial pointer or pointers, or a digital display, which indicate the altitude reading.
		The transponder obtains altitude data from a special altitude encoding altimeter or from a blind encoder; the latter being an electronic device which obtains current atmospheric pressure from the static pressure line and the reference pressure used is preset at 1013.2 hPa.
		Density altitude is roughly 120 feet greater than pressure altitude for each 1 °C that the temperature exceeds ISA for that level, and 120 feet less for each 1 °C that the outside air temperature is less than ISA.
	www.auf.asn.au /groundschool/umodule3.html (4116 words)

	Altitude - Wikipedia, the free encyclopedia
		Altitude is the elevation of an object from a known level or datum.
		It is the fall in pressure that leads to a shortage of oxygen (hypoxia) in humans on ascent to high altitude.
		Pressure altitude divided by 100 feet is referred to as the flight level; so when the altimeter reads 18,000 ft on the standard pressure setting the aircraft is said to be at "Flight level 180".
	en.wikipedia.org /wiki/Altitude (797 words)

	Pressure altitude - Wikipedia, the free encyclopedia
		It is primarily used in aircraft performance calculations, and in high-altitude flight (Class A airspace in the United States, which is controlled airspace at or above 18,000 feet).
		The relation between static pressure and pressure altitude is defined in terms of the properties of the International Standard Atmosphere (ISA).
		Measured or estimated Pressure at the Altitude of interest in inches of mercury (inHg).
	en.wikipedia.org /wiki/Pressure_altitude (155 words)

	MTP Altitude Discussion
		Allthough pressure altitude is a type of geopotential height, I discuss it separately because of it's importance in atmospheric research.
		Pressure altitude is used so that aircraft, which use static pressure to determine altitude, can agree upon what "altitude" they are flying at without having to continually update their altimeters with local pressure corrections.
		Pressure altitude is also useful to scientists involved with radiative transfer through the atmosphere since the absorption is normally expressed in terms of pressure (and other parameters such as temperature, frequency, and humidity).
	mtp.jpl.nasa.gov /notes/altitude/altitude.html (2857 words)

	Equations - Air Density and Density Altitude
		The density altitude is the altitude at which the density of the International Standard Atmosphere (ISA) is the same as the density of the air being evaluated.
		Density altitude has been a convenient yardstick for pilots to compare the performance of aircraft at various altitudes, but it is in fact the air density that is the fundamentally important quantity, and density altitude is simply one way to express the air density.
		The definition of density altitude is the altitude at which the density of the 1976 International Standard Atmosphere is the same as the density of the air being evaluated.
	wahiduddin.net /calc/density_altitude.htm (4137 words)

	Density Altitude (Site not responding. Last check: 2007-10-20)
		Since density varies directly with pressure, and inversely with temperature, a given pressure altitude may exist for a wide range of temperature by allowing the density to vary.
		Regardless of the actual altitude at which the airplane is operating, its performance will be as though it were operating at an altitude equal to the existing density altitude.
		Density altitude can be computed by applying the pressure altitude and outside air temperature at flight level to a navigation computer.
	avstop.com /AC/FlightTraingHandbook/DensityAltitude.html (360 words)

	Altitude Sickness \| AHealthyMe.com
		Altitude sickness is a general term encompassing a spectrum of disorders that occur at higher altitudes.
		Since the severity of symptoms varies with altitude, it is important to understand the range of the different altitudes that may be involved.
		High altitude is defined as height greater than 8,000 feet (2,438m); medium altitude is defined as height between 5,000 and 8,000 feet (1,524-2,438m); and extreme altitude is defined as height greater than 19,000 feet (5,791 m).
	www.ahealthyme.com /topic/topic13676 (1194 words)

	informationsphere.com: Air Pressure
		Pressure is a force, or weight, exerted on a surface per unit area, and is measured in Pascals (Pa).
		The pressure exerted by a kilogram mass on the Earth's surface is approximately 10 Pa. The pressure exerted by the whole atmosphere on the Earthís surface is approximately 100,000 Pa.
		Because pressure decreases with altitude, pressure observed at various stations must be adjusted to the same level, usually sea level.
	www.informationsphere.com /html/239.htm (288 words)

	Pressure Cooking
		In the pressure cookers of today, it is nearly impossible to blow up your kitchen, due mostly to the addition of safety valves that open and release excess steam if the pressure gets too high.
		After the pressure is released, remove the lid, bring the contents to a boil and reduce the liquid naturally.
		If the pressure cooker recipe instructions try to give total cooking time (from cold burner to finished cooking) then you might have to cook a little longer to achieve full pressure [authors note: this is because water boils at a lower temperature at high altitudes and lower heat = less pressure].
	www.dvo.com /newsletter/monthly/2004/july/tabletalk.html (1695 words)

	The Antarctic Sun: Physio-altitude
		Pressure altitude, while it exists near polar coastal areas, is even more pronounced on the polar plateau, where the physical altitude is well above sea level.
		A commonly mistaken explanation of pressure altitude is that it is the result of the centrifugal forces of the Earth’s spin that draws the atmosphere toward the equator to form an “equatorial bulge.”
		The average pressure over a one-week period in mid-summer at the South Pole ranges from about 670 to 675 mb, resulting in physiological altitudes of 11,034 to 10,790 feet and about 35 percent less oxygen than at sea level.
	antarcticsun.usap.gov /oldissues2002-2003/Sun020203/altitude.html (1022 words)

	Earth Atmosphere Model - Imperial Units
		Thus the air temperature is highest near the surface and decreases as altitude increases.
		In the troposphere, the temperature decreases linearly and the pressure decreases exponentially.
		In the lower stratosphere the temperature is constant and the pressure decreases exponentially.
	www.grc.nasa.gov /WWW/K-12/airplane/atmos.html (613 words)

	Pressure with Height: pressure decreases with increasing altitude
		Pressure with Height: pressure decreases with increasing altitude
		Since more than half of the atmosphere's molecules are located below an altitude of 5.5 km, atmospheric pressure decreases roughly 50% (to around 500 mb) within the lowest 5.5 km.
		Above 5.5 km, the pressure continues to decrease, but at an increasingly slower rate (to about 1 mb at 50 km).
	ww2010.atmos.uiuc.edu /(Gh)/guides/mtr/fw/prs/hght.rxml (145 words)

	High Altitude Cooking
		The boiling point is the temperature at which the pressure of the water vapor equals atmospheric pressure and the bubbles of water vapor are able to break through the surface and escape into the air.
		Although many sea-level cookie recipes yield acceptable results at high altitudes, they often can be improved by a slight increase in baking temperature; a slight decrease in baking powder or soda, fat and/or sugar; and/or a slight increase in liquid ingredients and flour.
		Although the cell structure of biscuits and muffin-type quick breads is firm enough to withstand the increased internal pressure at high altitudes without adjustment, a bitter or alkaline flavor may result from inadequate neutralization of baking soda or powder.
	www.coopext.colostate.edu /chaffee/highaltitude.html (999 words)

	NOVA Online \| Everest \| Atmospheric Pressure
		Pioneering scientists discovered atmospheric pressure (also known as barometric or air pressure) in the 17th century, and determined a startling new fact—that air actually has weight.
		Evangelista Torricelli, one of the first to discover atmospheric pressure, once said, "We live submerged at the bottom of an ocean of the element air." The Earth's gravitational field is pulling on air, and this pull, or "pressure" of air, is called atmospheric pressure.
		In fact, meteorologists monitor atmospheric pressure at the Earth's surface in order to determine whether the pressure is rising or falling, which helps to predict weather patterns.
	www.pbs.org /wgbh/nova/everest/exposure/pressure.html (571 words)

	Personal Cabin Pressure Altitude Monitor and Warning System
		Because the partial pressure of oxygen is reduced as altitude increases, hypoxia is a concern to flight crews when flying above 10,000 feet cabin pressure altitude.
		With the selection of a different pressure transducer and modification to the software, the device could be used to track the pressure, depth, and time profiles in human-tended underwater habitats and hyperbaric chambers.
		The flight units were tested in the laboratory, in an altitude chamber where normal ascent and rapid decompression profiles were flown, and in various pressurized and nonpressurized aircraft.
	rtreport.ksc.nasa.gov /techreports/2001report/500/516.html (900 words)

	Bomb - Wikipedia, the free encyclopedia
		This is especially important with airburst nuclear weapons, and in the case that the aircraft releases the bomb at low altitude.
		The explosion of the bomb has to be triggered by a detonator or a fuse.
		Detonators are triggered by clocks, remote controls like cell phones or some kind of sensor, such as pressure (altitude), radar, vibration or contact.
	en.wikipedia.org /wiki/Bomb (1620 words)

	Vapor Pressure and Altitude (Site not responding. Last check: 2007-10-20)
		The vapor pressure of a substance, is a property of the substance, and does not depend upon the atmospheric pressure, which in turn depends upon the altitude (among other things, of course).
		The boiling point of a substance is that temperature at which the vapor pressure equals to the applied pressure.
		The boiling point of a substance will depend upon the altitude, because the applied pressure is less and less, the higher the elevation.
	www.newton.dep.anl.gov /askasci/chem00/chem00717.htm (217 words)

	Altitude and Pressure
		As water is heated, its steam pressure rises, until it reaches the pressure of the surrounding air.
		This is because they were sealed at low altitude where the air pressure was high, and their internal pressure is thus the pressure of the air where they were sealed.
		At high altitudes, the pressure inside the bag is still the same as sea level air pressure, but the air pressure outside the bag is lower.
	www.newton.dep.anl.gov /askasci/phy00/phy00162.htm (585 words)

	Pressure and Altitude Sensors (Site not responding. Last check: 2007-10-20)
		Because of the change in the altitude reading as the watch temperature varies, it is important to keep track of the calibration temperature (i.e.
		As opposed to setting the correct altitude while the watch is at room temp (~ 65 degF) then putting it on, which will cause the altitude reading to change by about -60 ft when the watch temperature goes up to 80 degF on your hand.
		Once calibrated, I've found that altitude readings taken at the same watch temperature are quite accurate (within 20 ft), while readings taken at different watch temperatures can be corrected by adding in the correction factor (+40ft/+10degF) - Some performance data and graph are available.
	www.vinaka.com /nigel/casio (367 words)

	Upcoming Programs Colorado State University Cooperative Extension Tri River Area
		The weigh moves (rocks, jiggles or wiggles) to release excess pressure but the heat source must be controlled so the weight does not continually release steam by spewing.
		When pressure is released too frequently or constantly, liquid is pulled from the jars inside.
		Pressure canners are made from materials strong enough to withstand pressure.
	www.coopext.colostate.edu /TRA/cfs/food/pressure.html (2639 words)

	SSuits
		Historically speaking, the remote ancestors of today's high altitude full pressure suit are to be found in the full coverage, dry diving outfits of turn-of-the-century commercial salvage divers, with their ported brass helmets and valve fittings.
		The US Army's program to develop high altitude pressure suits is purported to have been substantially motivated by a requirement to protect James Doolittle's B-25 Mitchell crews during their planned high altitude Tokyo air raid in 1941.
		Henry's partial pressure suit operated by imposing mechanical pressure on the body directly, compressing the abdomen and limbs in the manner of a G-suit through the use of inflatable bladders in the abdominal area and pneumatic tubes (capstans) running along the limbs.
	webs.lanset.com /aeolusaero/Articles/SSuits.htm (5014 words)

	Gemini Space Suit Encyclopedia Article @ LaunchBase.com (Launch Base) (Site not responding. Last check: 2007-10-20)
		During the mission, Lovell was the first person to take his pressure suit off, which was achieved with great difficulty due to Lovell's size.
		Unfortunately, the Apollo 1 accident, which killed astronauts Grissom, White, and Roger Chaffee resulted in NASA cancelling the "Block I" program and starting with the flight of Apollo 7, testing the spacecraft in its "Block II" configuration, which included the new A7L spacesuit worn by its crew.
		Since Apollo, the Gemini spacesuit was looked at for the Manned Orbiting Laboratory program, but it has since been used as the baseline for all high-altitude pressure suits worn by U.S. Air Force, and later by NASA as its current ACES pressure suit.
	www.launchbase.com /encyclopedia/Gemini_Space_suit (551 words)

	At-Altitude Arithmetic
		Thus, the pressure at this altitude would increase by 1 at-attitude-atm every 27.9 feet (8.5 m) of descent/ascent (as opposed to every 33 feet (10.1 m) of sea water) at sea level.
		So, to maintain approximately the same pressure ratios as the U.S. Navy tables (or equivalent sea level derived tables) for determining decompression obligations, one needs to determine the actual number of "atmospheres pressure" at altitude and convert this to a sea level salt-water depth.
		Since, at altitude, the actual amount of water column that "defines" one at-altitude-atmosphere is less than 33 feet (10.1 m) of sea water, an ascent in a high altitude mountain lake must be slower than an ascent from the corresponding depth at sea level to maintain the same rate of pressure change with time.
	www.mindspring.com /~divegeek/altitude.htm (2092 words)

	AtmosModeler Simulator - Version 1.2a
		The stagnation temperature is the temperature of the airflow at a stagnation point, such as the leading edge of the wing or nose of the aircraft.
		The speed of sound depends on the type of gas in the atmosphere (nitrogen and oxygen for the Earth and carbon dioxide for Mars) and on the square root of the temperature of the gas.
		The dynamic pressure depends on the gas density and the square of the velocity and is an important design constraint on aircraft structures.
	www.grc.nasa.gov /WWW/K-12/airplane/atmosi.html (828 words)

	Colorado State University Cooperative Extension Resource Center
		If the atmospheric pressure is less, the temperature required for water to boil is less (Table 1).
		Because of the lower boiling point of water at high altitude, increase the processing time 1 minute for each 1,000 feet above sea level if the time is 20 minutes or less.
		Above that, decreased atmospheric pressure may result in excessive rising, which stretches the cell structure of the cake, making the texture coarse, or breaks the cells, causing the cake to fall.
	www.cerc.colostate.edu /titles/P41.html (1008 words)

	Altitude-Pressure Cabinets on ThomasNet.com
		Temperature, Humidity, Altitude, Vibration, Thermal Stock, ESS Chambers, Controlled Environment Rooms, Conditioned...
		Company Profile: Designer & manufacturer of standard & custom environmental test chambers for altitude, temperature, humidity, salt spray, thermal vacuum.
		Chamber Capabilites: Temperature, Humidity, Vacuum, Pressure, Altitude, Light & Vibration.
	www.thomasnet.com /products/altitudepressure-cabinets-9390204-1.html (303 words)

	Lab T3. Variation of Atmospheric Pressure with Altitude
		You can feel the pressure change in you ears as you ride the elevator, so it is not surprising that it can be measured with some precision.
		You can read the current air pressure (barometric pressure) in the 1140 Lab, in cm Hg, with the mercury barometer on the wall (Ask the TA where it is).
		The pressure change due to an adiabatic volume change depends on whether the gas in question is monatomic, like helium or neon, or diatomic, like the main components or air, oxygen and nitrogen.
	www.colorado.edu /physics/phys1140/phys1140_f98/Experiments/O2/O2.html (2197 words)

	Ears and Altitude
		It is the middle ear that causes discomfort during air travel, because it is an air pocket inside the head that is vulnerable to changes in air pressure.
		This is especially true when the airplane is landing, going from low atmospheric pressure down closer to earth where the air pressure is higher.
		Even after landing you can continue the pressure equalizing techniques, and you may find decongestants and nasal sprays to be helpful.
	www.entnet.org /healthinfo/ears/altitude.cfm (940 words)

	Pikes Peak 02
		Since the rate of pressure decrease is directly proportional to the density, there must be slower rate of decreasing pressure the higher up you go.
		In general during a high pressure it will feel like you are running at a lower altitude and during a low pressure it will feel like you are running at a higher altitude.
		ESLP is the station pressure increased (by an amount based on the principles discussed above) to a value that equates it to a common reference altitude, chosen to be sea level.
	www.skyrunner.com /story/pikespeako2.htm (3069 words)

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