EARTH SCIENCE
Geology, the Environment and the Universe
Chapter 11: Atmosphere
CHAPTER
11
Table Of Contents
Section 11.1 Atmospheric Basics
Section 11.2 Properties of the Atmosphere
Section 11.3 Clouds and Precipitation
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SECTION
11.1
Atmospheric Basics
Essential Questions
• What is the gas and particle composition of the
atmosphere?
• What are the five layers of the atmosphere?
• How is energy transferred in the atmosphere?
SECTION
11.1
Atmospheric Basics
• Energy is transferred throughout Earth’s
atmosphere.
Review Vocabulary
• atmosphere: the layer of gases that surrounds
Earth
SECTION
11.1
Atmospheric Basics
New Vocabulary
troposphere
exosphere
stratosphere
radiation
mesosphere
conduction
thermosphere
convection
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
• Air is a combination of gases, such as nitrogen
and oxygen, and particles, such as dust, water
droplets, and ice crystals.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Permanent atmospheric gases
• Earth’s atmosphere
consists mainly of
nitrogen (78 percent)
and oxygen (21
percent).
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Permanent atmospheric gases
• The amounts of nitrogen and oxygen in the
atmosphere are fairly constant over time.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Variable atmospheric gases
• The concentrations of some atmospheric
gases are not as constant over time as the
concentrations of nitrogen and oxygen.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Variable atmospheric gases
• The concentration of water vapor in the
atmosphere varies with the seasons, with the
altitude of a particular mass of air, and with
the properties of the surface beneath the air.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Variable atmospheric gases
• During the past 150 years, the concentration
of atmospheric carbon dioxide has increased,
due primarily to the burning of fossil fuels.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Variable atmospheric gases
• Molecules of ozone are
formed by the addition
of an oxygen atom to
an oxygen molecule.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Variable atmospheric gases
• The ozone layer
blocks harmful
ultraviolet rays from
reaching Earth’s
surface.
SECTION
11.1
Atmospheric Basics
Atmospheric Composition
Atmospheric particles
• Earth’s atmosphere contains variable amounts
of solids in the form of tiny particles, such as
dust, salt, and ice.
SECTION
11.1
Atmospheric Basics
Atmospheric Layers
• The atmosphere is classified into five different
layers: the troposphere, stratosphere,
mesosphere, thermosphere, and exosphere.
SECTION
Atmospheric Basics
11.1
Atmospheric Layers
Troposphere
• The layer closest to Earth’s surface, the
troposphere, contains most of the mass of
the atmosphere and is where weather occurs.
• In the troposphere, air temperature decreases
as altitude increases. The tropopause is the
altitude at which the temperature stops
decreasing.
SECTION
Atmospheric Basics
11.1
Atmospheric Layers
Stratosphere
• Above the tropopause is the stratosphere, a
layer in which the air temperature mainly
increases with altitude and which contains the
ozone layer.
• At the stratopause, air temperature stops
increasing with altitude.
SECTION
Atmospheric Basics
11.1
Atmospheric Layers
Mesosphere
• Above the stratopause is the mesosphere, in
which air temperature decreases with altitude.
• Temperatures stop decreasing with altitude at
the mesopause.
SECTION
11.1
Atmospheric Basics
Atmospheric Layers
Thermosphere
• The thermosphere is the layer above the
mesopause and contains the ionosphere.
SECTION
Atmospheric Basics
11.1
Atmospheric Layers
Exosphere
• The exosphere is the outermost layer of
Earth’s atmosphere and can be thought of as
the transitional region between Earth’s
atmosphere and outer space.
SECTION
11.1
Atmospheric Basics
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SECTION
11.1
Atmospheric Basics
Visualizing the Layers of the Atmosphere
• Earth’s atmosphere is made up of five layers.
Each layer is unique in composition and
temperature.
SECTION
11.1
Atmospheric Basics
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SECTION
11.1
Atmospheric Basics
Energy Transfer in the Atmosphere
• The total energy of the particles in an object due
to their random motion is called thermal energy.
SECTION
Atmospheric Basics
11.1
Energy Transfer in the Atmosphere
Radiation
• Radiation is the transfer of thermal energy
by electromagnetic waves.
• Thermal energy is transferred from the Sun
to Earth by radiation.
SECTION
Atmospheric Basics
11.1
Energy Transfer in the Atmosphere
Radiation
• Incoming solar radiation is either reflected back
into space or absorbed by Earth’s atmosphere
or its surface.
SECTION
Atmospheric Basics
11.1
Energy Transfer in the Atmosphere
Radiation
• The rate of absorption for any particular area
varies depending on the physical
characteristics of the area and the amount of
solar radiation it receives.
SECTION
Atmospheric Basics
11.1
Energy Transfer in the Atmosphere
Conduction
• Conduction is the transfer of thermal energy
between objects when their atoms or
molecules collide.
SECTION
Atmospheric Basics
11.1
Energy Transfer in the Atmosphere
Convection
• Convection is the transfer of thermal energy
by the movement of heated material from one
place to another.
SECTION
11.1
Atmospheric Basics
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SECTION
Section Check
11.1
Oxygen is the most abundant gas in
Earth’s atmosphere.
a. true
b. false
SECTION
11.1
Section Check
What causes weather on Earth?
a. heat from Earth’s interior
b. heat from the Sun
c. Earth’s magnetic field
d. Earth’s gravity field
SECTION
11.1
Section Check
By which criterion are layers of Earth’s
atmosphere defined?
a. by how temperature changes with height
b. by how pressure changes with height
c. by the types of clouds that form
d. by the types of precipitation that occur
Use with Chapter 11
Section 11.1
Energy transfer throughout the atmosphere
1)What is the source of all energy in the atmosphere?
2)List the three methods by which energy is transferred
throughout the atmosphere.
3)What role does radiation play in warming the atmosphere?
4)How does conduction transfer energy throughout the
atmosphere?
5)How does convection work with conduction to transfer energy
throughout
the atmosphere?
6)Infer how the transfer of energy in the atmosphere would be
different without convection.
7) Describe how air moves and changes in convection currents
in the atmosphere.
SECTION
11.2
Properties of the Atmosphere
Essential Questions
• What are the three main properties of the
atmosphere and how do they interact?
• Why do atmospheric properties change with
changes in altitude?
Review Vocabulary
• density: the mass per unit volume of a material
SECTION
11.2
Properties of the Atmosphere
• Atmospheric properties such as temperature, air
pressure, and humidity describe weather
conditions.
New Vocabulary
temperature inversion
relative humidity
humidity
dew point
saturation
latent heat
SECTION
11.2
Properties of the Atmosphere
Temperature
• Particles have more kinetic energy when they
are moving faster, so the higher the temperature
of a material, the faster the particles are moving.
SECTION
11.2
Properties of the Atmosphere
Temperature
Measuring temperature
• Temperature can be
measured in degrees
Fahrenheit, degrees
Celsius, or in kelvins.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
• Air pressure is the pressure exerted on a
surface by the weight of the atmosphere above
the surface.
• The units for pressure are N/m2.
• Air pressure is often measured in units of
millibars (mb), where 1 mb equals 100 N/m2.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Density of air
• The density and
pressure of the
layers of the
atmosphere
decrease as
altitude increases.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Pressure-temperature-density relationship
• In the atmosphere,
the temperature,
pressure, and
density of air are
related to each
other.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Pressure-temperature-density relationship
• Temperature, pressure, and density are all
related to one another.
• If temperature increases, but density is
constant, the pressure increases.
• If the temperature increases and the pressure
is constant, the density decreases.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Temperature inversion
• A temperature
inversion is an increase
in temperature with
height in an atmospheric
layer.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Temperature inversion
• If the land does not radiate thermal energy to
the lower layers of the atmosphere, such as
on a cold, clear, winter night when the air is
calm, the lower layers of air become cooler
than the air above them.
SECTION
11.2
Properties of the Atmosphere
Air Pressure
Temperature inversion
• A temperature inversion can lead to fog or
low-level clouds.
• In some cities, a temperature inversion can
worsen air-pollution problems.
SECTION
Properties of the Atmosphere
11.2
Air Pressure
Wind
• The movement of air is commonly known as
wind.
• In the lower atmosphere, air generally moves
from regions of higher density and pressure to
regions of lower density and pressure.
SECTION
Properties of the Atmosphere
11.2
Air Pressure
Wind
• Near Earth’s surface, wind is constantly slowed
by the friction that results from contact with
surfaces including trees, buildings and hills.
• Higher up from Earth’s surface, air encounters
less friction and wind speeds increase.
SECTION
11.2
Properties of the Atmosphere
Humidity
• Humidity is the amount of water vapor in the
atmosphere at a given location on Earth’s
surface.
SECTION
11.2
Properties of the Atmosphere
Humidity
Relative humidity
• Saturation occurs when the amount of water
vapor in a volume of air has reached the
maximum amount possible for that
temperature.
SECTION
11.2
Properties of the Atmosphere
Humidity
Relative humidity
• The amount of water vapor in a volume of air
relative to the amount of water vapor needed
for that volume of air to reach saturation is
called relative humidity.
SECTION
11.2
Properties of the Atmosphere
Humidity
Relative humidity
• The dew point is the temperature to which
air must be cooled at constant pressure to
reach saturation.
SECTION
11.2
Properties of the Atmosphere
Humidity
Relative humidity
• The extra thermal energy contained in water
vapor compared to liquid water is called
latent heat.
SECTION
11.2
Properties of the Atmosphere
Humidity
Condensation level
• A process in which temperature changes
without the addition or removal of thermal
energy from a system is called an adiabatic
process.
• Adiabatic heating occurs when air is
compressed, and adiabatic cooling occurs
when air expands.
SECTION
11.2
Properties of the Atmosphere
Humidity
Condensation level
• At equilibrium,
evaporation and
condensation
occur at equal
rates, so the
amount of water in
the liquid form
remains constant.
SECTION
11.2
Properties of the Atmosphere
Humidity
Condensation level
• Condensation occurs
at the lifted
condensation level
(LCL). Air above the
LCL is saturated and
thus cools more
slowly than air below
the LCL.
SECTION
Section Check
11.2
What is the relative humidity of a parcel
of air that has reached its dew point?
a. 25 percent
b. 50 percent
c. 75 percent
d. 100 percent
SECTION
Section Check
11.2
A sealed container holds only air. If the
temperature of the air inside the
container is increased, which other
property of the air also increases?
a. volume
b. density
c. pressure
d. mass
SECTION
11.2
Section Check
During which changes of state does
water release latent heat?
a. condensing and freezing
b. evaporating and melting
c. evaporating and freezing
d. condensing and melting
SECTION
11.3
Clouds and Precipitation
Essential Questions
• What is the difference between stable and
unstable air?
• How do low, middle, high, and vertical
development clouds differ?
• How does precipitation form?
SECTION
11.3
Clouds and Precipitation
• Clouds vary in shape, size, height of formation,
and type of precipitation.
Review Vocabulary
• condensation: process in which water vapor
changes to a liquid
SECTION
Clouds and Precipitation
11.3
New Vocabulary
condensation nucleus
cirrus
orographic lifting
precipitation
cumulus
coalescence
stratus
SECTION
11.3
Clouds and Precipitation
Cloud Formation
• As a warm air mass rises, it expands and cools
adiabatically.
• The cooling of an air mass as it rises can cause
water vapor in the air mass to condense.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
• A condensation nucleus
is a small particle in the
atmosphere around which
water droplets can form.
• When the number of these
droplets is large enough, a
cloud is visible.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric stability
• As an air mass rises, it cools. However, the air
mass will continue to rise as long as it is
warmer than the surrounding air.
• When an air mass sinks back to its original
position and resists rising, it is considered
stable.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric stability
• The stability of air masses determines the
type of clouds that form and the associated
weather patterns.
• Stable air has a tendency to resist movement.
Unstable air does not resist vertical
displacement.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric stability
• When the temperature of a
mass of air is greater than
the temperature of the
surrounding air, the air mass
rises. When the temperature
of the surrounding air is
greater than that of the air
mass, it sinks.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric lifting
• Clouds can form when moist air rises,
expands, and cools enough for water vapor to
condense.
• Clouds can also form when air is forced
upward or lifted by mechanical processes.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric lifting
• Orographic lifting
occurs when an air
mass is forced to
rise over a
topographic barrier.
SECTION
11.3
Clouds and Precipitation
Cloud Formation
Atmospheric lifting
• Air can be lifted by convergence, which occurs
when air moves into the same area from
different directions and some of the air is
forced upward.
• This process is even more pronounced when
air masses at different temperatures collide.
SECTION
11.3
Clouds and Precipitation
Types of Clouds
• Clouds are generally
classified by the
altitudes at which they
form and by their
shapes.
SECTION
Clouds and Precipitation
11.3
Types of Clouds
Low clouds
• Cumulus clouds are puffy, lumpy-looking
clouds that usually occur below 2000 m.
• Another type of cloud that forms at heights
below 2000 m is a stratus, a layered
sheetlike cloud that covers much or all of the
sky in a given area.
SECTION
11.3
Clouds and Precipitation
Types of Clouds
Middle clouds
• Altocumulus and altostratus clouds form at
altitudes between 2000 m and 6000 m and
are made up of ice crystals and water
droplets.
SECTION
11.3
Clouds and Precipitation
Types of Clouds
High clouds
• High clouds, made up of ice crystals, form at
heights above 6000 m where temperatures
are below freezing. Some, such as cirrus
clouds, often have a wispy, indistinct
appearance.
SECTION
11.3
Clouds and Precipitation
Types of Clouds
Vertical development clouds
• If the air that makes up a cumulus cloud is
unstable, the cloud will continue to grow
upward through middle altitudes as a towering
cumulonimbus. If conditions are right, it can
reach the tropopause.
SECTION
11.3
Clouds and Precipitation
Precipitation
• All forms of water that fall from clouds to the
ground are precipitation.
• Rain, snow, sleet, and hail are the four main
types of precipitation.
SECTION
11.3
Clouds and Precipitation
Precipitation
Coalescence
• Coalescence occurs when cloud droplets
collide and join together to form a larger
droplet.
• When the droplets become too heavy to
remain suspended in the cloud, they fall to
Earth as precipitation.
SECTION
11.3
Clouds and Precipitation
Precipitation
Snow, sleet, and hail
• The type of precipitation that reaches Earth
depends on the vertical variation of
temperature in the atmosphere.
SECTION
11.3
Clouds and Precipitation
Precipitation
The water cycle
• Water moves
from Earth to the
atmosphere and
back to Earth in
the water cycle.
SECTION
Section Check
11.3
Which adjective best describes cirrus
clouds?
a. dark
b. bulbous
c. wispy
d. tall
SECTION
Section Check
11.3
At which setting will orographic lifting
occur?
a. a mountain range
b. a flat plain
c. a large forest
d. a sandy desert
SECTION
11.3
Section Check
What is an unstable atmosphere?
Answer: An unstable atmosphere refers to a
condition in which rising parcels of air continue to
rise high into the atmosphere. For this to happen,
temperature in the surrounding atmosphere must
decrease with height at a faster rate than the rising
air mass cools adiabatically.
CHAPTER
Atmosphere
11
Resources
Earth Science Online
Study Guide
Chapter Assessment Questions
Standardized Test Practice
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SECTION
Atmospheric Basics
11.1
Study Guide
• Energy is transferred throughout Earth’s
atmosphere.
• Earth’s atmosphere is composed of several
gases, primarily nitrogen and oxygen, and also
contains small particles.
• Earth’s atmosphere consists of five layers that
differ in their compositions and temperatures.
SECTION
Atmospheric Basics
11.1
Study Guide
• Solar energy reaches Earth’s surface in the form
of visible light and infrared waves.
• Solar energy absorbed by Earth’s surface is
transferred as thermal energy throughout the
atmosphere.
SECTION
11.2
Properties of the Atmosphere
Study Guide
• Atmospheric properties, such as temperature,
air pressure, and humidity describe weather
conditions.
• At the same pressure, warmer air is less dense
than cooler air.
• Air moves from regions of high pressure to
regions of low pressure.
SECTION
11.2
Properties of the Atmosphere
Study Guide
• The dew point of air depends on the amount of
water vapor the air contains.
• Latent heat is released when water vapor
condenses and when water freezes.
SECTION
Clouds and Precipitation
11.3
Study Guide
• Clouds vary in shape, size, height of formation,
and type of precipitation.
• Clouds are formed as warm, moist air is forced
upward, expands, and cools.
• An air mass is stable if it tends to return to its
original height after it starts rising.
SECTION
Clouds and Precipitation
11.3
Study Guide
• Cloud droplets form when water vapor is cooled
to the dew point and condenses on
condensation nuclei.
• Clouds are classified by their shapes and the
altitudes at which they form.
• Cloud droplets collide and coalesce into larger
droplets that can fall to Earth as rain, snow,
sleet, or hail.
CHAPTER
Atmosphere
11
Chapter Assessment
In which layer of Earth’s atmosphere does
most of Earth’s weather occur?
a. troposphere
b. stratosphere
c. mesosphere
d. thermosphere
CHAPTER
Atmosphere
11
Chapter Assessment
How is energy moved during the process
of convection?
a. by electromagnetic waves
b. by colliding particles
c. by flowing matter
d. by electric currents
CHAPTER
Atmosphere
11
Chapter Assessment
Which cloud type is often associated with
strong thunderstorms?
a. cirrocumulus
b. altostratus
c. cirrostratus
d. cumulonimbus
CHAPTER
Atmosphere
11
Chapter Assessment
About how much of Earth’s incident solar
radiation is absorbed by Earth’s surface?
a. 20 percent
b. 30 percent
c. 50 percent
d. 60 percent
CHAPTER
11
Atmosphere
Chapter Assessment
An air mass starts to rise, becomes saturated,
and continues to rise. How does the rate at
which this air mass cools change as it rises?
CHAPTER
11
Atmosphere
Chapter Assessment
Possible answer: The air mass first cools at the
dry adiabatic lapse rate, which is about 10C per
1000 meters. After the air reaches its dew point
and becomes saturated, it cools more slowly at the
moist adiabatic lapse rate, which ranges from
about 4C per 1000 meters to about 9C per 1000
meters.
CHAPTER
Atmosphere
11
Standardized Test Practice
Which layer of Earth’s atmosphere includes
the ozone layer?
a. troposphere
b. stratosphere
c. mesosphere
d. thermosphere
CHAPTER
Atmosphere
11
Standardized Test Practice
Which is a measure of the average kinetic
energy of molecules in air?
a. pressure
b. temperature
c. density
d. humidity
CHAPTER
Atmosphere
11
Standardized Test Practice
Examine the graph showing air’s capacity for
water vapor at various temperatures. In which
temperature interval does the water vapor
capacity increase the least?
a. –20C to –10C
b. –10C to 0C
c. 20C to 30C
d. 30C to 40C
CHAPTER
Atmosphere
11
Standardized Test Practice
Which circumstance describes a temperature
inversion?
a. warmer air overlies cooler air
b. cooler air overlies warmer air
c. humidity increases with height
d. humidity decreases with height
CHAPTER
11
Atmosphere
Standardized Test Practice
How is wind related to air pressure?
Answer: Wind is the movement of air from a
region of high air pressure to a region of low air
pressure. Wind is strong if a large pressure
change exists through a short distance. Wind is
light if the air moves in response to a weak
pressure gradient.