Chapter 1: The Atmosphere

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Chapter 1 Key Terms

Absolute Zero

The temperature at which all molecular motion ceases (0 degrees Kelvin)

Aerosols

Particulates (very small liquid or solid particles) that are suspended in the atmosphere.

Atmosphere

The envelope of gases that surrounds the earth.

Carbon Dioxide

A trace gas that absorbs terrestrial radiation.

Density

Mass per unit volume.

Gas Law

The ratio of pressure to the product of temperature and density is always the same (P/DT = 1).

International Standard Atmosphere (ISA)

A model atmosphere based on average vertical distributions of pressure, temperature, and density as prescribed by international agreement.

Ionosphere

A deep layer of charged particles (ions and free electrons) that extends from the lower mesosphere upward through the thermosphere.

Kinetic Energy

The energy that exists by virtue of motion.

Mesopause

The upper limit of the mesosphere and the boundary between the mesosphere and thermosphere; slightly more than 280,000 feet MSL.

Mesosphere

A layer of the atmosphere where temperature decreases with height. The mesosphere is located immediately above the stratopause, between about 160,000 and 280,000 feet.

Nitrogen

Makes up 78% of the atmosphere. Nitrogen does not contribute to weather-producing processes under ordinary atmospheric conditions, although exceptions occur when it is subjected to very high temperatures.

Oxides of Nitrogen

Nitrogen combines with oxygen under extremely high temperatures to form these air pollutants.

Oxygen

21% of the atmosphere and its most important role is to support life. Concentration decreases with altitude. Supports combustion and contributes to both the formation and the destruction of air pollutants through chemical combinations with other gases.

Ozone

An unstable form of oxygen; greatest naturally occurring concentrations are in the stratosphere (ozone layer); abosrbs damaging ultraviolet solar radiation; prolonged exposure to high concentrations causes respiratory problems and causes some materials to deteriorate.

Ozone Hole

The region of the ozone layer that has a lower-than-normal concentration of ozone.

Ozone Layer

A layer of ozone found in the lower stratosphere near 80,000 feet MSL. Characterized by a relatively high concentration of ozone, this layer absorbs damaging UV radiation and is the cause of the increase of temperature with height in the stratosphere.

Particulates

Very small liquid or solid particles in the atmosphere. When suspended in the atmosphere, they are called aerosols.

Pressure

The force exerted by the moving molecules of the gas on a given area.

Standard Atmosphere (ISA)

An average atmosphere based on the following characteristics:
-A surface temperature of 15 deg C (59 deg F) and a surface pressure of 1013.25 mb (29.92 in. Hg.) at sea level,
-A lapse rate in the troposphere of approx. 2 deg C per 1,000 ft,
-A tropopause of approx. 36,000 ft with a temperature of -56.5 deg C.
-An isothermal lapse rate in the stratosphere to an altitude of approx. 80,000 ft.

Stratopause

Occurring at an altitude of about 160,000 ft MSL, the stratopause is the top of the stratosphere.

Stratosphere

The atmospheric layer above the tropopause, average altitude of base and top are 36,000 ft and 160,000 ft. In the ISA, the average, mid-latitude stratosphere is characterized by an isothermal lapse rate at the bottom of the layer, with an increase of temperature above.

Temperature

In general, the degree of hotness or coldness as measured on some definite temperature scale by means of any of various types of thermometers. Also, a measure of the direction of heat flow; and a measure of the mean kinetic energy of the molecules.

Thermosphere

The outer layer of the atmosphere that is directly adjacent to the mesosphere and where the temperature increases with an increase in altitude. The base of the thermosphere is about 280,000 ft.

Tropopause

The boundary between the troposphere and stratosphere, usually characterized by an abrupt change of lapse rate. In the ISA, the height of the tropopause is about 36,000 ft MSL. The height of the tropopause varies with season, latitude, and the presence or absence of local weather disturbances.

Troposphere

That portion of the atmosphere between the earth's surface and approximately 36,000 ft MSL. The average troposphere is characterized by decreasing temperature with height, and is the atmospheric layer where the great majority of clouds occur.

Water vapor

The gaseous form of water. Varies from trace amounts to 4% within our atmosphere.

What gases make up the earth's atmosphere?

78% Nitrogen, 21% Oxygen, and 1% other gases.

True or False: Carbon dioxide absorbs terrestrial radiation.

True

What are carbon dioxide and ozone also known as?

Trace gases

What are some ways to reduce pressure?

By cooling, by reducing mass, or by increasing volume.

When the density within a vessel is kept constant, how would you reduce its pressure?

By lowering the temperature.

When the temperature and volume of a vessel remain the same, how would you reduce its pressure?

The pressure could only be reduced by removing gas.

When the temperature and mass of the molecules in a vessel remain the same, how can we lower the pressure?

By increasing the volume of the vessel.

What is the distance in nautical miles from pole to equator?

5,397 n.m.

What is the circumference of the earth?

21,625 n.m.

What is the radius of the earth?

3,438 n.m.

Why is water vapor an important gas for weather production?

Because it can also exist as a liquid (water) and as a solid (ice). These contribute to fog, clouds, precipitation, and icing.

Where is the greatest concentration of ozone located?

Between 50,000 and 100,000 ft (within the stratosphere).

Why are particulates important?

Because they intercept solar and terrestrial radiation, provide surfaces for condensation of water vapor, reduce visibility, and can even foul engines (in the worst cases).

T/F: The greater the average kinetic energy, the lower the temperature.

FALSE: The greater the average kinetic energy, the GREATER the temperature.

What is absolute zero on the Kelvin scale?

0 degrees Kelvin - the point where all molecular motion ceases.

T/F: In general, density decreases with height.

True

T/F: Density can also be critically low near the ground because of very high surface temperatures.

True

What are the three standard atmospheric pressure values at sea level?

14.7 lbs/sq in
1013.25 mb
29.92 in. Hg.

What are two notable features of pressure curve?

1) Pressure always decreases with altitude.
2) Rapid decrease in pressure just above the ground and the very gradual decrease at the higher levels.

In the lower troposphere, how much altitude is gained for every one inch decrease of mercury?

Pressure decreases about one inch of mercury for each 1,000 feet of altitude gain.

In the lower troposphere, pressure decreases about _____ mb for each 1,000 feet of altitude gain.

34 mb

What is the Gas Law?

The ratio of pressure to the product of density and temperature is always the same. (P/DT = R)

At least half of the earth's atmosphere is located below _______ feet.

18,000 feet

At least 75% of the earth's atmosphere is located below _______ feet.

36,000 feet

At least 90% of the earth's atmosphere is located below _______ feet.

53,000 feet

Which atmospheric layer is located from sea level to 36,000 feet?

Troposphere

Which atmospheric layer is located from 36,000 feet to 160,000 feet?

Stratosphere

Which atmospheric layer is located from 160,000 feet to 280,000 feet?

Mesosphere

Which atmospheric layer is the highest layer, with temperatures increasing with altitude?

Thermosphere

What are the four atmospheric layers we discussed in this chapter?

Troposphere, stratosphere, mesosphere, thermosphere.

What is the tropopause and where is it located?

The tropopause is the upper boundary of the troposphere and is located at 36,000 feet MSL.

What is the stratopause and where is it located?

The stratopause is the upper boundary of the stratosphere and is located at 160,000 feet MSL.

What is the mesopause and where is it located?

The mesopause is the upper boundary of the mesosphere and is located at 280,000 feet MSL.

Where is the ozonosphere located?

In the lower stratosphere.

T/F: Temperature maximums near stratopause are due to the absorption of solar radiation by the ozone.

True

What is the ionosphere?

A deep layer of charged particles (ions and free electrons) that extends from the lower mesosphere upward through the thermosphere.

In what atmospheric layer is most of our atmosphere contained?

The troposphere

In the ISA troposphere, how many degrees Celsius does the temperature decrease for each 1,000 feet of altitude gained?

2 degrees Celsius

T/F: The great majority of the clouds and weather occurs in the stratosphere.

FALSE - The great majority of the clouds and weather occurs in the TROPOSPHERE.

What is the temperature value at the tropopause?

-58 degrees Celsius

What is the temperature value at the stratopause?

0 degrees Celsius

Why is oxygen recommended at lower altitudes at night (vs higher altitudes in the day)?

Because night vision is affected by a decreased oxygen supply (hypoxia).

Most clouds and weather occur in what atmospheric layer?

The troposphere because about 75% of the mass of our atmosphere is contained below 36,000 feet MSL.

In the ISA, the tropopause is found at what altitude?

36,000 feet MSL

What is the ISA tropopause temperature?

-58 degrees celsius

You are flying an ER-2 at 65,000 feet. In which atmospheric layer(s) are you located?

The stratosphere because it is located above 36,000 feet MSL and below 160,000 feet MSL.

If you were to fly directly from the pole to equator at a ground speed of 300 knots, how long would it take?

About 18 hours (Divide the distance of 5,397 nm by the speed of 300 knots).

You have just taken off from an airport located at sea level. Conditions are exactly as prescribed by the ISA. What will be your outside air temperature (OAT) at 1,000 feet?

13 degrees Celsius

You have just taken off from an airport located at sea level. Conditions are exactly as prescribed by the ISA. What will be your outside air temperature (OAT) at 1,500 feet?

12 degrees Celsius

You have just taken off from an airport located at sea level. Conditions are exactly as prescribed by the ISA. What will be your outside air temperature (OAT) at 32,000 feet?

-49 degrees Celsius

A dry gas is in a closed vessel. What happens to the pressure of the gas if the density remains the same and the temperature goes up?

The pressure would increase as the kinetic energy increases.

A dry gas is in a closed vessel. How do you keep the pressure inside a vessel constant when you increase the temperature?

You would have to decrease the density by reducing the mass (allowing gas to escape).

A dry gas is in a closed vessel. How do you decrease the pressure and keep the density constant?

Decrease the temperature to lower the kinetic energy of the molecules which, in turn, lowers the pressure.

What are the typical symptoms of hypoxia?

Air hunger, fatigue, nausea, headache, dizziness, hot and cold flashes, tingling, visual impairment, and euphoria.

How long can one typically operate without supplementary oxygen at 15,000 feet MSL?

About 30 minutes

How long can one typically operate without supplementary oxygen at 20,000 feet MSL?

About 15 minutes

How long can one typically operate without supplementary oxygen at 30,000 feet MSL?

About 1 minute

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