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Atmosphere
Chapter 23
Meteorology
 Study
of the atmosphere.
 Meteorologists are scientists who
study all the characteristics of the
atmosphere.
 They also study weather and
climate.
Weather
Is
the general condition of the
atmosphere at a particular
time and place.
Includes temperature, air
movements, and moisture
content.
Climate
General
weather conditions
over many years.
Meteorology

Meteorologists apply their forecasting skills
to special fields such as agriculture,
aviation, forestry, or health.
Composition of the Atmosphere
Air is a mixture of chemical elements and
compounds.
 Most abundant elements in the air are
gases: nitrogen, oxygen, and argon.
 Most abundant compounds are gases:
carbon dioxide and water vapor.

Water vapor
Added to air by evaporation.
 Most evaporation comes from the oceans,
but also includes ponds, lakes, streams,
and the soil.
 Plants give off water vapor during
transpiration.
 It is removed during evaporation:
condensations and precipitation.

ozone
Another important substance in the upper
atmosphere in a form of oxygen.
 Protects the earth from harmful ultraviolet
rays of the sun.
 Human activities have harmed the ozone
layer: CFCs-chlorofluorocarbons such as
from refrigerators and air conditioners.

Atmospheric Dust
Atmosphere contains various kinds of tiny
solid particles.
 Includes mineral particles lifted from fields
by winds.
 Volcanic dust and microscopic organisms.

Oxygen in the Atmosphere
Amount is the result of natural process.
 Animals, bacteria, & plants remove oxygen
from the air as part of their life processes.
 Forest fires, burning of fuels, &
weathering of some rocks also use up
oxygen.
 Produce during photosynthesis.

Nitrogen in the Atmosphere
Amount of nitrogen in the atmosphere is
maintained through the nitrogen cycle.
 Nitrogen moves from the air to the soil, to
plants & animals, & back again to the air.
 Nitrogen is removed from the air mainly
by the action of nitrogen-fixing bacteria.

Nitrogen fixation
Microscopic organisms live in the soil & on
the roots of certain plants. These bacteria
convert the nitrogen to a form that plants
can use.
 Ammonia nitrate

Atmospheric Pressure
Gravity pulls the gases of the atmosphere
toward the earth’s surface & holds them
there.
 Due to gravity, 99% of the total mass of
the atmospheric gases is found with in 32
km of the earth’s surface.

Atmospheric Pressure
Ration of the force of the air to the area of
the surface on which it presses.
 If you have been in an airplane or high in
the mountains, you have felt the effect of
sensation on your ears. A popping
sensation or your ears filling up with air.

Mercurial Barometer
An instrument that measures pressure.
 Atmospheric pressure presses on the
liquid mercury in a well at the base of the
barometer.
 A reading of 760 mm of mercury indicates
standard atmospheric pressure, or 1
atmosphere.
 Weather maps use millibars (mb). 1 mb is
equal to 0.001 of standard atmospheric
pressure.

Types of Barometers
Aneroid barometer is a type of barometer
that does not contain mercury. Aneroid
means “without liquid”.
 Altimeter can also measure altitude above
sea level.

Layers of the Atmosphere

4 layers are: troposphere, stratosphere,
mesosphere, and thermosphere.
Troposphere
Atmospheric layer closest to the earth’s
surface.
 In Greek it means, “change”.
 Almost all the water vapor & carbon
dioxide in the atmosphere is found here.
 Tropopause-temperature remains nearly
constant.

Stratosphere
Layer of the atmosphere that extends
upward from the tropopause to an
altitude of 50 km.
 Stratosphere is the high-temperature
zone, that marks the upper boundary.

Mesosphere
Above the stratopause & extending to an
altitude of about 80 km is this atmospheric
layer.
 Mesopause is the upper boundary that is
marked by a return to increasing
temperatures.

Thermosphere
Atmospheric layer above the mesopause.
 Temperature increases steadily with
altitude.
 Thermometer cannot accurately measure
the temperature here because the air is
thin.

Thermosphere continued
Ionosphere is the lower region of the
thermosphere, at an altitude of 80 km to
550 km.
 Exosphere os the zone of indefinite
altitude. It extends for thousands of
kilometers above the earth.

Air Pollution
Any substance that is harmful to people,
animals, plants, or property.
 Substances found in air that are
pollutants: sulfur dioxide, carbon
monoxide, lead, & hydrocarbons.
 Mains source is the burning of fossil fuels.

Air Pollution continued
Acid precipitation is another harmful side
effect of the burning of fossil fuels.
 Air pollution can become a more serious
problem as result of certain weather
conditions.
 Temperature inversion is when a layering
of warm air on top of cool air.
 Controlled by preventing air pollutants.

Section Review 23.1
1. What are the two most abundant
elements in dry air at sea level?
 2. What does a barometer measure?
 3. In which layer of the atmosphere do
weather changes occur?

Answers



1. Nitrogen & oxygen
2. atmospheric pressure
3. the troposphere
23.2 Solar Energy & the
Atmosphere

Earth’s atmosphere is heated in several
ways by the transfer of energy from the
sun.
Radiation
All of the energy that the earth receives
from the sun travels through space
between the earth & the sun.
 Includes all forms of energy that travels
through space as waves.
 Cannot see the forms called X-rays & radio
waves.

Radiation continued
Travels through space in the form of
waves at high speed.
 Wavelength is the distance from one wave
crest.
 Various types of radiation differ in the
length of their waves.
 Visible light consists of waves you see in
different colors.

Radiation continued
Wavelengths shorter than visible include
ultraviolet rays, z-rays, & gamma rays.
 Longer wavelengths include infrared waves &
radio waves.
 Electromagnetic waves make up all forms of
radiation.

Radiation continued
Electromagnetic spectrum is a complete
range of wavelengths.
 Most energy reaching the earth from the
sun is in the form of electromagnetic
waves.

Skin Cancer

The amount of ultraviolet radiation that
does reach the earth’s surface causes
sunburn on skin that is exposed to direct
sunlight too long.
Scattering
Clouds, dust, and gas molecules in the
atmosphere affect the path of radiation
from the sun.
 Means that water droplets and dust
suspended in the atmosphere reflect and
bend the rays.

Reflection
20 % of solar energy is absorbed by
atmosphere.
 30 % is scattered back into space or is
reflected from clouds or earth’s surface.
 50 % is absorbed by the surface.
 Chart on page 465 shows reflection and
absorption by different surfaces.

Albedo
The fraction of solar radiation reflected by
a particular surface is albedo.
 Albedo of the moon is .07 %.
 What percent of the total solar energy
reaching the moon is reflected?

Absorption & Infrared Energy
The warmth of the sun you feel is infrared
rays.
 Infrared rays produced by materials on the
earth’s surface is mostly absorbed by
water vapor and carbon dioxide.

Greenhouse Effect
Process by which the atmosphere traps
infrared rays over the earth’s surface.
 Increased carbon dioxide levels have
caused the earth to be a warmer planet.
 Global warmin

Variations in Temperature
Factors causing changes in temperature
are:
 Latitude
 Elevation

Conduction and Convection
Conduction is when molecules in a
substance move faster as they are heated.
 Type of energy transfer in which vibrating
molecules pass heat along to other
vibrating molecules by direct contact.
 Convection is the energy transfer of heat
through the movement of heated material.

Section 23.2 Review
1. What type of solar radiation causes
sunburn?
Answer: ultrviolet

2. Why is the atmospheric pressure lower
beneath a mass of warm air than beneath
a mass of cold air?
Answer:
Because warm air is less dense than cold air
and thus presses down on the earth with
less force than an equal volume of cold air.

23.3 Winds

Because the earth receives more solar
energy at the equator than at the poles,
there is a belt of low air pressure at the
equator.
Global Winds
Circulation of the atmosphere as well as
the oceans is affected at the rotation of
the earth on its axis.
 Rotation of the earth causes surface winds
in the Northern Hemisphere to deflect to
the right and those in the Southern
Hemisphere to the left. This motion is
called the Coriolis effect.

Convection Cells
This is the air flowing from the equator
completes three looping patterns of flow.
 Northern and Southern Hemispheres each
have three convection cells.

Trade Winds
Winds in both hemispheres flowing toward
the equator between 30 degrees and 0
degrees latitude.
 Trade winds flowing from the northeast
are called northeast trades.
 Trade winds in the Southern Hemisphere
are called southern trades.

Doldrums

This is a trade wind system of the
Northern and Southern Hemispheres meet
at the equator in this narrow zone.
Horse latitudes
This is the subtropical high-pressure belt.
 The surface winds here are weak and
changeable. The name horse latitudes
was given to this region.

Westerlies
Flow of winds in both Northern and
Southern Hemispheres.
 Northern Hemisphere, the westerlies are
southwest winds.
 Southern Hemisphere, the westerlies are
northwest winds.
 Located in the belt between the 40 degree
& 60 degree latitude.

Polar Easterlies
Third wind belt near the poles.
 Poleward of the belt of westerlies, at
about 60 degree latitude, is a belt of low
pressure.
 Subpolar lows result from warm air
moving poleward from subtropical high is
lifted by cold polar air moving toward the
equator.

Polar easterlies
Surface winds created by the polar high
pressure are deflected by the Coriolis
effect.
 Strongest coming off the Antarctica.

Jet Streams
Bands of high-speed winds exist in the
upper troposphere & lower stratosphere
over both the Northern & Southern
hemisphere. Known as upper westerly
winds.
 Pressure differs because of the
temperature of polar air & middle-latitude
air differs so greatly.
 Cold polar air is much denser than the
warmer air of the middle latitudes.

Polar Jet Stream
Resulting pressure differences of the air
from the cold dense air produces the polar
jet stream.
 Polar jet streams are important because
they control the path of storms & have an
effect on the airline routes.

Breeze
Gentle winds that extend over distances of
less than 100 km are called breezes.
 These winds are our local winds that are
not apart of global wind belts.

Land & Sea Breezes
Warmer air above the land rises, and the
cool air above the water moves in to
replace it.
 Cool wind moving from water to land is
called a sea breeze.
 Overnight the land cools more rapidly than
the water does, and the sea breeze is
replaced by a land breeze.
 Land breeze flows from the cooler land to
the warmer water.

Mountain & Valley Breeze

In mountain regions during the daylight
hours, a gentle valley breeze blows up the
slopes.

Then, cooler air descends from the
mountain peaks, creating a mountain
breeze.
Section 23.3 Review

1. What are the results of the Coriolis
effect on wind flow?

Answer: Winds veer to the right in the
Northern Hemisphere and to the left in the
Southern Hemisphere.
Review cont
2. What surface wind belt flows in the
middle latitudes?

Answer: Westerlies
Review cont
3. On a camping trip on the Oregon
coast, you decide to hike to the ocean, but
you are not sure of the direction. The
time is 4:00 P. M. How might the breeze
help you find the ocean? Why?

Answer: If you walk against the breeze,
you can find the ocean. The cool sea
breeze, blowing from the water to land,
begins in the afternoon.