Transcript EARTH PROCESSES

Composition of the atmosphere; Contains
layers based on altitude and pressure
Nitrogen @ 78%, from volcanic eruptions and
when dead plants and animals decay.
Oxygen @ 21%, produced mainly from
plants.
CO2, Argon, water vapor and other gasses
@ 1%,
water vapor is the only substance that exists
in the atmosphere as a solid, liquid and gas.
Life Science Connection
Photosynthesis and respiration are
linked to gas exchange between
organisms and the atmosphere.
Photosynthesizing plants use CO2,
water and light energy to produce
oxygen. During respiration, plants and
animals consume oxygen and release
CO2.
AIR PRESSURE
Air pressure is the measure of
the force with which the air
molecules push on a surface.
Pressure
The earth’s atmosphere is held
around the planet by gravity.
With
altitude,
pressure
decreases. So, is air pressure
greater at the surface of the
earth or at 50,000 ft?
ALTITUDE
Altitude is the height of an object
above the Earth’s surface. As
altitude increases, air pressure
decreases.
Is That A Fact !
The oxygen in the Earth’s current
atmosphere is produced by phytoplankton
(tiny, drifting sea plants) and land plants
that
release
oxygen
during
photosynthesis.
Layers of the
Atmosphere (4 layers)
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
Troposphere
The layer in which we live
and is 90% of the total mass,
contains almost all of the
Earths’ CO2, H2O vapor,
clouds, air pollution, life-forms
and weather.
Stratosphere
The atmospheric layer above the
troposphere is called the stratosphere. In
the stratosphere, the air is very thin and
contains little moisture. The lower
stratosphere
is
extremely
cold,
measuring
about
-600C.
In
the
stratosphere, the temperature rises with
increasing altitude. This occurs because
of ozone.
OZONE
Ozone is a molecule that is made up of
three oxygen atoms. Almost all of the
ozone in the atmosphere is contained in
the ozone layer of the stratosphere. Ozone
absorbs solar energy in the form of
ultraviolet radiation, warming the air. By
absorbing the ultraviolet radiation, the
ozone layer also protects life at the
Earth’s surface.
Mesosphere
Above the stratosphere is the
mesosphere. The mesosphere is the
coldest layer of the atmosphere. As on
the troposphere, The temperature
drops
with
increasing
altitude.
Temperatures can be as low as
-930C at the top of the mesosphere.
Scientists have recently discovered
large wind storms in the mesosphere
with winds reaching speeds of more
than 320 km/h.
Thermosphere
This is the uppermost layer of the
atmosphere and the temperature will
increase with altitude because the many
gasses absorb solar radiation and can
reach temperatures of 1,7000C. While
the thermosphere has very high
temperatures, it would not feel hot.
Temperature and heat are not the same
thing.
Thermosphere
(contd.)
Temperature is the measure of the
average energy of particles in motion. A
high temperature means that the particles
are moving very fast. Heat, on the other
hand, is the transfer of energy between
objects of different temperature. But in
order to transfer energy, particles must
touch
each
other.
Part
of
the
thermosphere is the Ionosphere.
IONOSPHERE
In the upper mesosphere and the lower
thermosphere, nitrogen and oxygen atoms
absorb harmful solar energy, such as Xrays and gamma rays. This absorption not
only contributes to the thermosphere’s
high temperatures but also causes the gas
particles to become electrically charged.
Electrically charged particles are called
ions: therefore, this part of the
thermosphere is called the ionosphere.
QUIZ
1. What are the two main gasses in
Earth’s atmosphere?
2. What is atmospheric pressure?
3. Name the layers of the atmosphere,
starting with the one closest to the
Earth.
4. What is the ozone layer and why is it
important to Earth?
ANSWERS
1. Nitrogen and Oxygen
2. Atmospheric pressure is the force exerted by
molecules of air on a surface.
3. Troposphere, Stratosphere, Mesosphere,
Thermosphere.
4. The ozone layer is a layer of ozone molecules
in the stratosphere. The layer filters ultraviolet
radiation from the sun and prevents much of
this radiation from reaching Earth.
Energy in the Atmosphere
Energy in the Atmosphere
The Earth receives energy from the
sun by radiation. Radiation is the
transfer of energy from the sun by
electromagnetic waves. Although the
sun releases a huge amount of
energy, the Earth receives only about
two-billionths of this energy. Yet even
this small amount of energy has a
very large impact on Earth. Like
standing in the sun, you can feel the
warmth.
Conduction
This is the transfer of thermal
energy from one material to
another by direct contact.
Like walking on hot cement or
sand. Thermal energy always
moves from hot to cold.
Convection
Most thermal energy in the atmosphere
moves by convection. Convection is the
transfer of thermal energy by the
circulation or movement of a liquid or
gas. Warm air is less dense and rises as
it cools and becomes denser it sinks.
This continual process creates a circular
movement of air called convection
current.
The Greenhouse Affect
•
•
•
The gasses in the atmosphere act like the
layer of glass in the greenhouse trapping the
heat.
Thermal energy is absorbed by objects in the
greenhouse and then radiates this heat
warming the air.
Not all gasses in the atmosphere trap thermal
energy, the ones that do are called
greenhouse gasses. Some scientists believe
that global warming is a cycle of the earth but
is being accelerated by the burning of fossil
fuels.
Global Warming
In recent decades, many scientists have
become concerned that an increase in
greenhouse gasses, particularly carbon
dioxide, may be causing an increase in the
greenhouse effect. These scientists have
hypothesized that a rise in carbon dioxide
as a result of human activity has led to an
increased global temperature. A rise in
average global temperatures is called
global warming.
QUIZ
1. What is radiation?
2. What is a convection current?
1.Energy transferred as electromagnetic
waves.
2.The continual, circular movement of
warm and cool particles in a liquid or
gas.
Why Air Moves
Wind is created by differences in air
pressure. The greater the pressure
difference is, the faster the wind
moves. This difference in air
pressure is generally caused by the
unequal heating of the Earth. For
example, the air at the equator is
warmer and less dense. This warm
less dense air rises.
Why Air Moves (contd.)
As it rises, it creates an area of low
pressure. At the poles, however, the air is
colder and more dense. Colder, more
dense air is heavier and sinks. This cold,
sinking air creates areas of high pressure.
Pressure differences in the atmosphere at
the equator and at the poles cause air to
move. Because air moves from areas of
high pressure to areas of low pressure,
winds generally move from the poles to
the equator.
PRESSURE BELTS
As warm air rises over the equator, it
begins to cool. Eventually, it stops rising
and begins moving towards the poles. At
about 300 north and 300 south latitude,
some of the cool air begins to sink. This
cool, sinking air causes a high pressure
belt near 300 north and 300 south latitude.
At the poles, cold air sinks. As this air
moves away from the poles and along the
Earth’s surface, it begins to warm.
PRESSURE BELTS
(contd.)
As the air warms, the pressure drops,
creating a low-pressure belt around
600 north and 600 south latitude. The
circular patterns caused by the rising
and sinking of air are called
convection cells.
Coriolis Effect
The movement of the wind is
affected by the rotation of the
earth and causes the air
currents to travel in a curved
pattern.
Coriolis Effect (contd.)
Winds don’t blow directly north or
south. The movement of wind is
affected by the rotation of the Earth.
The Earth’s rotation causes the wind
to travel in a curved path rather than
a straight line. The curving of moving
objects, such as wind, by the Earth’s
rotation is called the Coriolis effect.
Coriolis Effect (contd.)
Because of the Coriolis effect, the
winds in the Northern Hemisphere
curve to the right, and those in the
Southern Hemisphere curve to the
left.
WEiRD SCIENCE
In addition to affecting the ocean and
atmosphere currents, the Coriolis effect
can also be observed in river systems.
Rivers in the Northern Hemisphere erode
their right banks more than their left banks.
Because the Mississippi River and the
Yukon River flow roughly north-south in
sections, they are good examples of this
effect.
Types of Winds
Two main types wind; both
types are caused by uneven
heating of the Earth. Local
Winds and Global Winds.
Wind is moving air.
Local Winds
Local Winds can blow from any
direction and usually only travel
short distances. These are affected
by the geography of an area. The
land will heat up faster than water
and cools faster at night creating
high and low pressures and a
breeze.
Global winds
Global winds are part of a
pattern of winds that circulate
and moves across the earth.
Trade winds
Trade winds, are in both
hemispheres, these are winds
that blow from 300 latitude
towards the equator and curve
due to the Coriolis effect.
WESTERLIES
The westerlies are wind belts found in both
the Northern and Southern Hemispheres
between 300 and 600 latitude. The
westerlies flow towards the poles in the
opposite direction of the trade winds. The
westerlies helped early traders return to
Europe.
Jet Streams
Jet Streams are narrow belts
of high speed air that blow in
the upper troposphere and
lower stratosphere at speeds
up to 500km/hr.
QUIZ
1. What is wind?
2. How does air temperature over landmasses
and adjacent bodies of water change between
night and day?
3. What is the Coriolis effect?
1. Air that flows between air masses of different pressures
and temperatures.
2. During the day, the air is cooler over water. At night, the
air is cooler over land.
3. The deflection of moving objects due to Earth’s rotation.
Types of Air Pollution
Primary pollution; These are
pollutants that are put directly
into the air by humans or
natural activity. Like exhausts
from vehicles and volcanic
eruptions.
Types of Air Pollution
(contd.)
Secondary pollution; is formed from
chemical reactions that occur when
primary pollutants come in contact with
other primary pollutants or with naturally
occurring substances like water vapor.
Many secondary pollutants are formed
when a primary pollutant reacts with
sunlight.
Human-caused air Pollution
Human-caused air pollution comes from
a variety of sources. The major source of
air pollution today is transportation. Cars
contribute about 60% of the humancaused air pollution in the United States.
The oxides that come from car exhaust,
such as nitrogen oxide, contribute to
smog and acid rain. Oxides are chemical
compounds that contain oxygen and
other elements.
INDUSTRIAL AIR
POLLUTION
Many industrial plants and electric
power plants burn fossil fuels to get
their energy. But burning fossil fuels
causes large amounts of oxides to be
released into the air. In fact, the
burning of fossil fuels in industrial and
electric power plants is responsible
for 96% of the sulfur oxides released
into the atmosphere.
INDOOR AIR POLLUTION
Air pollution is not limited to the outdoors.
Sometimes the air inside a home or
building is even worse than the air outside.
The air inside a building can be polluted by
the compounds found in new carpets,
paints and building materials can also add
to IAP, especially if the windows and doors
are tightly sealed.
The Air Pollution Problem
Air pollution is both a local and global
concern. Local air pollution such as smog,
generally affects large cities. Air pollution
becomes a global concern when local
pollution moves away from its source.
Winds can move pollutants from one place
to another, sometimes reducing the
amount of pollution in a source area but
increasing it in another place.
Acid Precipitation
Precipitation that contains acids from air
pollution is called acid precipitation.
When fossil fuels are burned, they release
oxides of sulfur and nitrogen into the
atmosphere. When these oxides combine
with water droplets in the atmosphere,
they form sulfuric acid and nitric acid,
which
fall
as
precipitation.
Acid
precipitation has many negative effects on
the environment.
The Clean Air Act
The Clean Air Act helps to control
industrial pollution by requiring
that scrubbers are used to
remove pollutants from coal
burning plants. It also controls the
amount of pollutant allowed from
each source.
QUIZ
1. Classify each of the following as either a
primary or a secondary pollutant.
2. What are the three sources of air
pollution.
1.Primary pollutants are tobacco, smoke
and chalk dust. Secondary pollutants are
smog and acid rain.
2.Motor vehicles, industries, electric power
plants.