regional gliding school the pressure of the atmosphere at any point is due to the weight of...

Regional Gliding School

The pressure of the atmosphere at any The pressure of the atmosphere at any point is due to the weight of overlying point is due to the weight of overlying air. Pressure at the surface of the earth is air. Pressure at the surface of the earth is normally measured by the mercury normally measured by the mercury barometer and is expressed in inches of barometer and is expressed in inches of mercury. The mercury barometer mercury. The mercury barometer consists of an open dish of mercury into consists of an open dish of mercury into which the open end of an evacuated which the open end of an evacuated glass tube is placed. Atmospheric glass tube is placed. Atmospheric pressure forces the mercury to rise in the pressure forces the mercury to rise in the

tube. The great the pressure thetube. The great the pressure the higher higher the column rises.the column rises.

Mercury Barometer

Mercury Dish

Glass Tube

Atmospheric Pressure

Vacuum


PressurePressureForce per unit areaForce per unit area

Inches of MercuryInches of MercuryThe unit used to measure the length of a column of mercury The unit used to measure the length of a column of mercury in the barometer ("Hg).in the barometer ("Hg).

MillibarsMillibarsThe pressure exerted on an area of 1 square cm by a force The pressure exerted on an area of 1 square cm by a force of 1000 Dynes (mb). of 1000 Dynes (mb).

KilopascalsKilopascalsEquals 10 hectopascalsEquals 10 hectopascalsOne hectopascal equals one millibars (hPa).One hectopascal equals one millibars (hPa).

Unit of Measure


ICAO - International Civil Aviation Organization

a)a) Mean sea level pressureMean sea level pressure

29.92”Hg29.92”Hg

1013.2 mb1013.2 mb

101.3 kPa101.3 kPa

c)c) Air is a perfectly Air is a perfectly

dry gasdry gas d)d) Lapse rate isLapse rate is

1.98°C/1000ft1.98°C/1000ft

b)b) Mean sea level Mean sea level temperaturetemperature

15°C15°C


Density is mass per unit volume.

Pressure and Density are directly proportional. As density increases so does pressure.


NOTE: You must use the buttons in the Confirmation Stage


A

B

C

D

15oC

1.98oC

2.0oC

29.92oC

Let's try a few review questions on Meteorology:

Question #1 - Describe the ICAO mean sea level temperature?

MeteorologyMeteorologyAtmospheric Pressure and DensityAtmospheric Pressure and Density

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Flying Scholarship Program


That answer is correct.

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ICAO - International Civil Aviation Organization

a)a) Mean sea level pressureMean sea level pressure

29.92”Hg29.92”Hg

1013.2 1013.2 mbmb

101.3 101.3 kPakPa

c)c) Air is a perfectly Air is a perfectly

dry gasdry gas

d)d) Lapse rate isLapse rate is

1.98°C/1000ft 1.98°C/1000ft

b)b) Mean sea level temperatureMean sea level temperature

15°C15°C


A

B

C

D

Inches of Mercury

Isobar

kilopascals

Both A and C


Question #2 - What are the units of measure of pressure?



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PressurePressureForce per unit areaForce per unit area

InchesInchesof of MercuryMercuryThe unit used to measure theThe unit used to measure thelength of a column of length of a column of mercury in the barometermercury in the barometer("Hg).("Hg).

MillibarsMillibarsThe pressure exerted on an area of 1 square cm by a The pressure exerted on an area of 1 square cm by a force of 1000 Dynes (mb). force of 1000 Dynes (mb).

KilopascalsKilopascalsEquals 10 hectopascalsEquals 10 hectopascals

One hectopascal equals one millibars (hPa).One hectopascal equals one millibars (hPa).

Unit of Measure


Altimeter Setting

The barometric pressure reading is used to adjust the altimeter for variations in existing atmospheric pressure or to the standard altimeter setting.

If set to the existing pressure it will read the true elevation of the airport above sea level.

It is measured in inches of mercury.


Meteorological Aspects of the Altimeter

When flying from an area of high pressure to an area of low pressure the altimeter will read higher than what the aircraft is actually flying.

HLIntended Path

Actual Path

HIGH TO A LOW, LOOK OUT BELOW


Meteorological Aspects of the Altimeter

When flying from an area of low pressure to an area of high pressure the altimeter will read lower than what the aircraft is actually flying.

LOW TO A HIGH, CLEAR BLUE SKY

HL

Intended Path

Actual Path


NOTE: You must use the buttons in the Confirmation Stage


A

B

C

D

Aerodrome

Area

Sea

Ground


Question #3 - The altimeter reads the altitude above level.



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Altimeter Setting

The barometric pressure reading is used to adjustthe altimeter for variations in existing atmosphericpressure or to the standard altimeter setting.

If set to the existing pressure it will read the trueelevation of the airport above sea level.




Question #4 - What unit of measure is the altimeter expressed in?


A

B

C

D

Inches of Mercury

Isobar

kilopascals

Both A and C


Let's try again...




Let's move on...


Altimeter Setting

The barometric pressure reading is used to adjustthe altimeter for variations in existing atmosphericpressure or to the standard altimeter setting.

If set to the existing pressure it will read the trueelevation of the airport above sea level.



Congratulations!!

You have now completed the Atmosphere Pressure and Density lesson of the Meteorology Module. Of course, this lesson is always available to you for future reference if required.

You are now ready to move along to the next Meteorology lesson you have not completed or to any other module you wish. You can advance to the Self Test Module if you feel ready to challenge the final exam.

Good Luck!


regional gliding school the pressure of the atmosphere at any point is due to the weight of...

Documents

c slide

density slide

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existing pressure

area of low pressure

area of high pressure

unit of measure slide

existing atmospheric