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Did you come!5 nice birthday gifts that men will love

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Wikipedia related words

If there is no explanation, there is no corresponding item on Wikipedia.


(I.e.(Kiatsu,English: air pressure[1]) Isgas OfpressureThat is.When we simply say "atmospheric pressure"Atmospheric pressure(Taikiatsu,English: atmospheric pressure[1],atmospherePressure) in many cases.

(I.e.Is also a unit of measurement.JapaneseMeasurement LawThen,pressureLegalunitIt is defined as (described later).

Gas pressure

The pressure of the gas istemperature,volumeAffected by.For example, the gas remains in a constant volume (corresponding to the state of being confined in a container).heatingThen, the atmospheric pressure is almost the same as the temperatureProportionalAnd rise.The relationship between atmospheric pressure, volume, and temperature isBoyle's law,Charles' Law,Boyle-Charles' lawIt is indicated by.

The pressure of the gas isMixed gasIn the case of, the pressure of each of the constituent gases (Partial pressure) Is the total.

Atmospheric pressure

空 気AlsomaterialBecausemassIs subject to the gravity of the earth.On the contraryCompressive stressIn addition, the atmosphere is in a state of mechanical equilibrium due to the balance between gravity and this.地球Of the atmosphere coveringFloorBySea surfaceThen, the area is 1 cm2Approximately 1kgf permercuryApproximately 76 cm in pillar,WedIn the case of, it is equivalent to about 10m).thisAtmospheric pressureOr simply(I.e.That is.The higher the place, the lower the height of the air column above it, and the lower the air pressure.The pressure of 1 at atmospheric pressure on the sea surfaceunitAlso used as.

At seawater vaporevaporationByUpdraftOf the air wheredensityThe same, such as a slight decrease in air pressure and a slight decrease in atmospheric pressure.Above sea levelheightHowever, the atmospheric pressure changes little by little, and the level of atmospheric pressure constantly changes.The mountains and valleys of this barometric pressure(I.e.,(I.e.Called.When there is a difference in air pressure, high-pressure air flows into the low-pressure region.This isWindIt is the main cause.

For measuring barometric pressurebarometer,Radio sonde(See also Article 1-2 of the Meteorological Service Act and Article 1-3 of the Meteorological Service Act).

Weather informationSo, the unit of atmospheric pressure used to beCGS unit system OfMillibar (mb),Torr (Torr) orMillimeters of mercury (mmHg) was used, but nowInternational unit system (SI)Hectopascal (hPa) is used.

Fluctuations in atmospheric pressure

Atmospheric pressureheight,latitudeIt also changes depending on.The standard atmospheric pressure (1 atm) is 1013.25 hPa above sea level, but since atmospheric pressure is a pressure that indicates the weight of the air above, it decreases as you go higher.The ratio of altitude rise to pressure drop is 10 hPa for a rise of about 1.2 m at low altitude, which is calculated to be about 0.7 atm at the summit of Mt. Fuji, about 5,500 atm at an altitude of 0.5 m, and about 0.3 atm at the summit of Everest. Become.[Question]However, since the air density differs depending on the altitude (depending on the atmospheric pressure), the ratio of the atmospheric pressure decrease to the altitude increase is not constant.As the altitude rises, the ratio of altitude rise to pressure drop becomes gradual.Utilizing the change in atmospheric pressure due to such altitudeAltimeterIs also made.

Also, the atmosphereSun lightSuch asheatAs a result, when heated locally, the volume increases and the density decreases.The expanded light air is pushed up by the surrounding heavy air, creating an updraft.Conversely, when the atmosphere cools, the volume decreases, the density increases, and it settles.DowndraftGive birth.

Depending on the latitude, the heat that the atmosphere and the surface receive from the sunEnergy densityIs different.equatorialCompared to the surroundings, where the atmosphere is warm and hot throughout the year,Polar regionsThe surroundings are always cold.Due to the temperature difference of the atmosphere due to such latitude, peculiar ascending and descending currents occur just below the equator and in the polar regions.Tropical convergence zone,Extreme high pressure zoneTo form.Due to the pressure difference, the wind blows from the high pressure area to the low pressure area,Trade wind,Westerlies,Far East windWill be.They are,Hadley circulation(With the Intertropical Convergence ZoneSubtropical high pressure zonewhile),Ferrel cell(With the subtropical high pressure zoneHigh latitude low pressure zonewhile),Polar vortexIt is called (between the high latitude low pressure zone and the extremely high pressure zone).Such a large-scale circulation of the atmosphere,Atmospheric circulationCalled.Also,oceanとLandCompared with seawaterHeat capacityDue to its size, the ocean has less temperature change than the land.Therefore, in a situation where sunlight is strong, the land is often hotter than the ocean, and a low pressure system is arranged on the land and a high pressure system is arranged on the ocean, and a wind blows from the ocean to the land.The opposite is true in situations where the land is cooled.This willSea breeze,monsoonOccurs.

Events related to atmospheric pressure

In addition, many daily events and life phenomena are adapted and used under atmospheric pressure.

Atmospheric pressure as a unit

As mentioned above, atmospheric pressure at sea level is pressure (especially atmospheric pressure andWater pressure) Is also used as a unit.The atmospheric pressure on the sea surface is defined as "1 atmospheric pressure".The original definition of "atmospheric pressure" as a unit is "atmospheric pressure at sea level", but atmospheric pressure varies depending on the location and weather conditions.Therefore, as a standard value of atmospheric pressure at sea levelStandard atmospheric pressureWas defined, and this value was defined as 1 atm.

Standard atmospheric pressure is1954The 10thInternational Weights and Measures General Assembly Exactly 101 325 in (CGPM) Pascal It was set as (Pa).This was originally 760 Millimeters of mercury (mmHg) is converted to Pascal and rounded down to the nearest whole number.

Atmospheric pressure is nowInternational unit system It is not defined in (SI).But JapanMeasurement LawIs defined as the statutory unit of measure[2]..The definition in the Measurement Law is 1954 101 Pascal, the same as in the 325 CGPM.[3].

Unit symbol

Atmospheric pressure unit symbol means atmosphere atmosphere Derived from ATM Is[4].

Relationship between atmospheric pressure, millimeter of mercury, and torr

Millimeters of mercuryとTorrHas exactly the same definition in the measurement law system, and both are accurate 101 325/760 Pa Is[5][6]. this isStandard atmospheric pressure Of1⁄760It means that.It corresponds to about 133.322 Pa.

Also, 1 atmosphere is 1 bar The number is close to (1atm = exactly 1.01325) bar) Is 1.325% different.


  1. ^ a b Ministry of Education,Japan Meteorological SocietyChapter "Academic glossary Meteorology ”Japan Society for the Promotion of Science, 1987, revised edition.ISBN 4-8181-8703-8.
  2. ^ Measurement Law Appendix XNUMX Pressure column, barometric pressure
  3. ^ Measurement Unit Ordinance Appendix XNUMX Item No. 2, Pressure, Atmospheric pressure column "Pascal or Newton XNUMX times per square meter"
  4. ^ Measurement unit rule Appendix 2 Pressure (second column), barometric pressure column, "atm"
  5. ^ Measurement Unit Ordinance Appendix XNUMXItem No. 12, Blood pressure measurement, Millimeter of mercury, "XNUMX, XNUMX minutes per square meter of Pascal or Newton"
  6. ^ Measurement Unit Ordinance Appendix XNUMXItem No. 11, Measurement of pressure in the living body, Torr, "Pascal or Newton, XNUMX minutes of XNUMX per square meter"

Related item

外部 リンク

Unit of pressure
Pascal(SIunit)barEngineering atmospheric pressure(I.e.Torrpsi
1 Pa≡ 1 N/m2= 10−5 bar≈ 10.2×10-6 at≈ 9.87×10-6 ATM≈ 7.5×10-3 Torr≈ 145×10-6 psi
1 bar= 100000 Pa≡ 106 dyn/cm2≈ 1.02 at≈ 0.987 atm≈ 750 Torr≈ 14.504 psi
1 at= 98066.5 Pa= 0.980665 bar≡ 1 kgf / cm2≈ 0.968 atm≈ 736 Torr≈ 14.223 psi
1 atm= 101325 Pa= 1.01325 bar≈ 1.033 at≡ p0= 760 Torr≈ 14.696 psi
1 Torr≈ 133.322 Pa≈ 1.333 × 10−3 bar≈ 1.360 × 10−3 at≈ 1.316 × 10−3 ATM≡ 1 mmHg≈ 19.337 × 10−3 psi
1 psi≈ 6894.757 Pa≈ 68.948×10-3 bar≈ 70.307 × 10−3 at≈ 68.046 × 10−3 ATM≈ 51.7149 Torr≡ 1 lbf/in2


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