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Topic: Standard atmosphere

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Atmospheric pressure

Torr

Standard conditions for temperature and pressure

Barometer

Pressure altitude

Standard temperature and pressure

Pascal

Density altitude

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	The Standard Atmosphere
		A considerable part of the discrepancy is due to the release of latent heat as warm, humid air is convected from the lower levels to higher ones: when the air cools to the point where condensation of water vapor into cloud droplets occurs, the latent heat is released to become “sensible heat”.
		Because the lower atmosphere is continually overturned by convection, it's called the troposphere.
		These upper layers contribute little to atmospheric refraction, partly because they are much less dense than the troposphere, and partly because any line of sight from the ground crosses the upper layers at angles farther from grazing.
	mintaka.sdsu.edu /GF/explain/thermal/std_atm.html (521 words)

	The Atmosphere
		The standard atmosphere is a hypothetical model that lists average (mean) conditions for atmospheric composition, pressure, temperature, and several other parameters in a motionless, stable atmosphere from sea level to an altitude of 1,000 kilometers (about 621 miles) and without considering the variations that occur with the seasons.
		The standard atmosphere is useful when the vertical distribution of pressure, temperature, density, and speed of sound is required such as when calibrating aircraft altimeters and determining aircraft and rocket performance and design.
		Since the standard atmosphere does not indicate true conditions at a particular time and place, it is important for a pilot to contact a local airport for local atmospheric conditions.
	www.centennialofflight.gov /essay/Theories_of_Flight/atmosphere/TH1.htm (1485 words)

	Atmospheric pressure Summary
		He correctly surmised that the atmospheric pressure upon the mercury in the bowl kept the tube from draining completely, and the vacant area at the top of the tube was a vacuum.
		Standard atmospheric pressure or "the standard atmosphere" (1 atm) is defined as 101.325 kilopascals (kPa) or 760 mmHg.
		Atmospheric pressure is often measured with a mercury barometer, and a height of approximately 760 mm (30 inches) of mercury is often used to teach, make visible, and illustrate (and measure) atmospheric pressure.
	www.bookrags.com /Atmospheric_pressure (2330 words)

	Newsletter
		An atmosphere which has a relative humidity of 65 per cent and temperature of 20° C. In tropical and sub-tropical countries, an alternative standard temperature of 27° C may be used.
		A textile material is in standard condition (or 'conditioned') for physical testing when, after having been dried to approximately constant weight in an atmosphere with a relative humidity not higher than 10 per cent, it has been kept in the standard atmosphere for testing until it has reached equilibrium.
		Equilibrium with the standard atmosphere for testing may be deemed to have been reached when successive weighings, carried out at intervals of not less than two hours, of the textile materials freely exposed to the moving air differ by less than 0.25 per cent.
	www.premier-1.com /itn/tech_update2_19.html (2166 words)

	Aircraft Performance
		A standard decrease in density as altitude increases
		The standard atmosphere definition provides a means for instrument and aircraft manufacturers to specify the performance of their products in a uniform way.
		This equivalent altitude in the Standard Atmosphere is the DENSITY ALTITUDE.
	webusers.warwick.net /~u1007204/gs/perf.html (1996 words)

	chapt2
		The standard atmosphere.- For purposes of pressure altimeter calibrations, aircraft and rocket performance and their design, and so forth, knowledge of the vertical distribution of such quantities as pressure, temperature, density, and speed of sound is required.
		In the troposphere (from sea level to 10 to 20 km in the standard atmosphere), it is seen that the temperature decreases linearly with altitude.
		Although in the standard atmosphere the air is motionless with respect to the Earth, it is known that the air mass through which an airplane flies is constantly in a state of motion with respect to the surface of the Earth.
	history.nasa.gov /SP-367/chapt2.htm (3182 words)

	AMS Glossary
		A hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc.
		The current standard atmosphere is that adopted in 1976 and is a slight modification of one adopted in 1952 by the International Civil Aeronautical Organization (ICAO), which, in turn, supplanted the NACA Standard Atmosphere (or U.S. Standard Atmosphere) prepared in 1925.
		With respect to radio propagation, that hypothetical atmosphere in which standard propagation exists, that is, one in which the index of refraction decreases with height at a rate of 12 N- units per 1000 ft.
	amsglossary.allenpress.com /glossary/search?id=standard-atmosphere1 (703 words)

	Aerospaceweb.org \| Ask Us - Speed of Sound & Standard Atmosphere
		In addition, the speed of sound is based on an approximation of the atmosphere called the standard atmosphere.
		By comparison, the standard atmosphere that we use on our site is the 1976 version in which the temperature at sea level is assumed to be 59°F (15°C).
		Since atmospheric properties will vary at any given location on the Earth at any given time, it was necessary to develop an atmospheric model that approximates the conditions with sufficient accuracy to represent the actual atmosphere across the planet.
	www.aerospaceweb.org /question/atmosphere/q0160.shtml (766 words)

	Aeronautics - Characteristics of the Flight Atmosphere (PRESSURE) - Level 2
		However, changes in atmospheric pressure occur for aviators not only as they fly into or out of high- and low-pressure cells but also as they climb or descend in their airplanes.
		The standard atmosphere is based on average conditions at 40° north latitude where the average pressure is 29.92 inches of mercury and the average temperature is 59° Fahrenheit (F) or 15° Celsius (C).
		Atmospheric temperature is based on the amount of heat absorbed or reflected by the Earth's surface.
	www.allstar.fiu.edu /aerojava/flight23.htm (723 words)

	Atmosphere, Pressure, Forces
		Mobility, capacity for expansion and capacity for compression are the principal properties of the atmosphere.
		Since the weight of the atmosphere decreases with altitude, it follows that the atmospheric pressure reading at a station at 5000 feet elevation will be less than that at a station at 1000 feet and still less than that at a station at sea level.
		To have a consistent record of the distribution of atmospheric pressure, it is necessary to reduce the station pressures to a common level.
	www.allstar.fiu.edu /aero/fltenv2.htm (3425 words)

	Mars Atmosphere Model - English Units
		The Martian atmosphere is an extremely thin sheet of gas, principally carbon dioxide, that extends from the surface of Mars to the edge of space.
		The density of the atmosphere depends on both the temperature and the pressure through the equation of state and also decreases with increasing altitude.
		In the upper atmosphere the temperature decreases linearly and the pressure decreases exponentially.
	exploration.grc.nasa.gov /education/rocket/atmosmre.html (566 words)

	Project 3
		This standard is important in discussing my topic because all three states of water exist in the atmosphere and in the process of cloud formation.
		This standard is important because students will learn of certain forms of precipitation that exist in the atmosphere and on Earth when clouds are present.
		This standard shows how students will learn the water cycle process and understand it's importance in the atmosphere and how clouds are formed and give-off precipitation.
	www.umd.umich.edu /sep/students/harrismn/harrismn_peres.html (1965 words)

	Pressure
		Since the static fluid pressure is dependent only upon density and depth, choosing a liquid of standard density like mercury or water allows you to express the pressure in units of height or depth, e.g., mmHg or inches of water.
		The mercury barometer is the standard instrument for atmospheric pressure measurement in weather reporting.
		For weather applications, the standard atmospheric pressure is often called 1 bar or 1000 millibars.
	hyperphysics.phy-astr.gsu.edu /hbase/pman.html (538 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.
		The 1976 International Standard Atmosphere is mostly described in metric SI units, and I have chosen to use those same units (in general).
		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 (4207 words)

	Standard conditions for temperature and pressure - Wikipedia, the free encyclopedia
		In industry and commerce, it is necessary to define the standard reference conditions of temperature and pressure when expressing a gas volume or a volumetric flow rate because the volume of a gas varies with the temperature and pressure of the gas.
		In aeronautics and fluid dynamics the term "International Standard Atmosphere" is often used to denote the variation of the principal thermodynamic variables (pressure, temperature, density, etc.) of the atmosphere with altitude at mid latitudes.
		During those same years, the most commonly used standard reference conditions for people using the Imperial or customary USA system of units was 60 °F (520 °R) and 14.696 psia (i.e., 1 atmosphere of absolute pressure) because it was almost universally used by the oil and gas industries worldwide.
	en.wikipedia.org /wiki/Standard_temperature_and_pressure (1755 words)

	July Newsletter '98
		Since all airplane performance is compared and evaluated in the environment of the standard atmosphere, all of the airplane's performance instrumentation is calibrated for the standard atmosphere.
		Pressure altitude is the altitude in the standard atmosphere, corresponding to a particular pressure level.
		The airplane altimeter is essentially a sensitive barometer calibrated to indicate altitude in the standard atmosphere.
	airports.pilotage.com /events/fresno/fres0798.htm (1060 words)

	The Earth's Atmosphere
		The original atmosphere may have been similar to the composition of the solar nebula and close to the present composition of the Gas Giant planets, though this depends on the details of how the planets condensed from the solar nebula.
		That atmosphere was lost to space, and replaced by compounds outgassed from the crust or (in some more recent theories) much of the atmosphere may have come instead from the impacts of comets and other planetesimals rich in volatile materials.
		The atmosphere of the Earth may be divided into several distinct layers, as the following figure indicates.
	csep10.phys.utk.edu /astr161/lect/earth/atmosphere.html (655 words)

	AtmosModeler Simulator - Version 1.2a (Site not responding. Last check: 2007-10-10)
		It uses mathematical models of the standard atmosphere of the Earth and Mars.
		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)

	Standard atmosphere - Wikipedia, the free encyclopedia
		The standard Atmospheric pressure -- a reference value at sea-level
		The US Standard Atmosphere -- a series of models that define values for pressure, density, and temperature over a range of altitudes
		The International Standard Atmosphere (ISA) -- an international standard model, defining typical atmospheric properties with altitude, at mid-latitude.
	en.wikipedia.org /wiki/Standard_atmosphere (113 words)

	[No title] (Site not responding. Last check: 2007-10-10)
		The atmosphere boundary layer thickness is the "depth" or "height" of the (atmosphere) planetary boundary layer.
		Atmosphere_Xward_stress is a stress which tends to accelerate the atmosphere in direction X. The specification of a physical process by the phrase due_to_process means that the quantity named is a single term in a sum of terms which together compose the general quantity named by omitting the phrase.
		Atmosphere water vapor content is sometimes referred to as "precipitable water", although this term does not imply the water could all be precipitated.
	www.cgd.ucar.edu /cms/eaton/cf-metadata/standard_name.xml (13414 words)

	Earth Atmosphere Model - Metric Units (Site not responding. Last check: 2007-10-10)
		The Earth's atmosphere is an extremely thin sheet of air extending from the surface of the Earth to the edge of space.
		The model was developed from atmospheric measurements that were averaged and curve fit to produce the given equations.
		This is the atmosphere model used in the FoilSim simulator.
	www.grc.nasa.gov /WWW/K-12/airplane/atmosmet.html (591 words)

	Lesson 1 Page (Site not responding. Last check: 2007-10-10)
		The standard atmosphere is an idealize atmosphere used as a reference the vertical variations in temperature, pressure and density.
		The standard atmosphere is used in determining altitude from pressure altimeters.
		You must keep in mind that while the standard atmosphere is very useful as a reference tool for aviation, there are large variations from the standard atmosphere on any given day and region.
	profhorn.meteor.wisc.edu /wxwise/wxpilot/lesson1/lesson1b.html (314 words)

	Arnold Publishing - Civil Jet Aircraft Design - Atmosphere and Airspeeds
		In this standard, height above sea-level is measured as the true (tape-line) distance (the geometric altitude) assuming constant gravitational acceleration (g) with height (i.e.
		The standard defines the sea-level (quoted as SL and meaning zero altitude) air temperature as 288.15°K (15°C) and then assumes a linear variation with height up to 11 km (about 36089 ft) to a temperature of 216.65°K. This region is called the 'troposphere'.
		In the lower regions The atmosphere in the lower regions is assumed to follow normal gas laws.
	www.apnet.com /companions/034074152X/appendices/data-d/default.htm (1087 words)

	International Standard Atmosphere
		Pressure, temperature, density, viscosity and speed of sound variation for the international standard atmosphere (ISA) can be calculated for a range of altitudes from sea level upward.
		In the lower region, the troposphere, the atmosphere has a lapse rate (L) of 6.5K/Km.
		Based on the above equations, an application is available which shows atmospheric properties for a specific altitude.
	www.ae.su.oz.au /aero/atmos/atmos.html (639 words)

	Standard Atmospheres (Site not responding. Last check: 2007-10-10)
		The U.S. Standard Atmosphere, 1976 (USSA1976) [1] consists of two parts, the lower atmosphere below 86 km altitude and the upper atmosphere from 86 km to 1000 km altitude.
		The lower atmosphere is further separated into seven regions expressed in geopotential height H (m').
		The unofficial Australian standard atmosphere, 2000 (UASA2000) is the same as USSA1976, except for the upper atmosphere.
	www.sworld.com.au /steven/space/atmosphere (400 words)

	US Std Atmosphere
		US Standard Atmosphere 1976 is an average, piece-wise continuous, mid-latitude temperature profile of the earth's atmosphere.
		It is defined as having a temperature of 288.15 K at mean sea level (0 km geopotential height = 1013.25 hPa) with various lapse rates which change at seven specified geopotential heights.
		In this equation, we use the letter "s" to denote standard atmosphere values, and the subscript i denotes the level from which the integration is being initiated.
	mtp.jpl.nasa.gov /notes/altitude/StdAtmos1976.html (301 words)

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