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EARTH PROCESSES – PowerPoint PPT presentation

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Composition of the atmosphere Contains layers
based on altitude and pressure Nitrogen _at_ 78,
from volcanic eruptions and when dead plants and
animals decay. Oxygen _at_ 21, produced mainly from
plants. CO2, Argon, water vapor and other gasses
_at_ 1, water vapor is the only substance that
exists in the atmosphere as a solid, liquid and
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.

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  • Air pressure is the measure of the force with
    which the air molecules push on a surface.

The earths 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 is the height of an object above the
    Earths surface. As altitude increases, air
    pressure decreases.

Is That A Fact !
  • The oxygen in the Earths 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

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  • 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.

  • 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 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 Earths surface.

  • 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.

  • 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.

  • In the upper mesosphere and the lower
    thermosphere, nitrogen and oxygen atoms absorb
    harmful solar energy, such as X-rays and gamma
    rays. This absorption not only contributes to the
    thermospheres 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.

  • What are the two main gasses in Earths
  • What is atmospheric pressure?
  • Name the layers of the atmosphere, starting with
    the one closest to the Earth.
  • What is the ozone layer and why is it important
    to Earth?

  1. Nitrogen and Oxygen
  2. Atmospheric pressure is the force exerted by
    molecules of air on a surface.
  3. Troposphere, Stratosphere, Mesosphere,
  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.

  • 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.

  • 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.

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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.

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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

  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.

  • 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
    Earths surface, it begins to warm.

  • 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

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 dont blow directly north or south. The
    movement of wind is affected by the rotation of
    the Earth. The Earths 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 Earths 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.

  • 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

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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.

  • 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.

  1. What is wind?
  2. How does air temperature over landmasses and
    adjacent bodies of water change between night and
  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 Earths

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.

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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 human-caused 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.

  • 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.

  • 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

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.

  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
  2. Motor vehicles, industries, electric power plants.