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Chapter 17 Notes: The Atmosphere

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Title: Chapter 17 Notes: The Atmosphere


1
Chapter 17 Notes The Atmosphere
2
What is the Atmosphere?
  • The atmosphere can be defined as the portion of
    planet earth that contains gas.
  • Weather can be defined as the current state of
    the atmosphere at any given time or place.
  • Climate can be defined as the average weather
    conditions of a given area.

3
What is the Composition of the Earth's Atmosphere?
  • About 99 of air is Nitrogen and Oxygen.
  • About 0.93 of air is Argon.
  • About 0.039 of air is Carbon Dioxide.
  • Water vapor is also an important component of the
    atmosphere.
  • One form of oxygen in the atmosphere is ozone.
    Ozone protects living organisms from harmful
    ultraviolet radiation from the sun.

4
Ozone
5
How does air pressure and temperature change with
altitude?
  • As altitude (height above sea level) increases,
    air pressure decreases.
  • Air pressure is simply the pressure created by
    the weight of air above it.
  • More air pressure creates more kinetic energy,
    and a higher temperature.
  • As a general rule, the higher the altitude, the
    lower the air pressure will become, the lower the
    air pressure, the colder the temperature.

6
Air Pressure
7
How does air pressure and temperature change with
altitude?
  • However, not all of the earth's layers of the
    atmosphere get colder with height.
  • The earth's atmosphere can be divided into four
    layers based on changing temperatures.
  • The first layer which starts at the earth's
    surface and goes up to about the height of 5-10
    miles, is called the troposphere.
  • The troposphere gets colder with height.

8
Troposphere
9
How does air pressure and temperature change with
altitude?
  • Then there is an area of change between layers
    called the tropopause.
  • The next layer is called the stratosphere.
  • The stratosphere remains a constant temperature
    until about 15 miles above sea level, where it
    reaches the ozone layer.
  • Once the stratosphere reaches the ozone layer it
    heats up until it reaches the next layer, which
    is the mesosphere.

10
Troposphere and Stratosphere
11
Troposphere and Stratosphere
12
How does air pressure and temperature change with
altitude?
  • The mesosphere begins about 30 miles high.
  • The mesosphere gets colder with height.
  • The last and final layer is the thermosphere
    which begins about 50-60 miles high.
  • Includes the ionosphere and exosphere.
  • Only a small percentage of the atmosphere's mass
    is in the thermosphere.
  • Increased solar radiation causes the temperature
    in the thermosphere to increase.

13
Mesosphere and Thermosphere
14
Layers of the Atmosphere
15
Aurora Borealis is Produced in the Thermosphere
16
What causes the seasons of the earth?
  • The earth rotates on its axis every day.
  • The earth revolves around the sun every year.
  • The earth's axis is not perpendicular to the
    orbit or the path that it takes around the sun.
  • The earth has a tilted axis.
  • The earth is tilted 23.5 degrees from a line that
    is perpendicular to the earth's orbit around the
    sun.

17
Earth's Tilted Axis
18
What causes the earth's seasons?
  • It is this 23.5 degree tilted axis that causes
    the earth to experience seasonal changes in the
    weather across the earth.
  • In places like the equator, the sun's full force
    is experienced nearly year round.
  • In places like the north and south pole, daylight
    and darkness can last for months at a time.
  • Places in between have four distinct seasons.

19
Earth's Tilted Axis and the Seasons
20
When are the solstices and equinoxes?
  • In the Northern Hemisphere, the summer solstice
    or longest day of the year is on June 21 or 22.
  • In the Northern Hemisphere, the winter solstice
    or shortest day of the year is on December 21 or
    22.
  • September 22 or 23 is the autumnal equinox.
  • March 21 or 22 is the spring equinox.

21
The Seasons
22
Heat in the Atmosphere
  • The definition of heat is the thermal energy that
    is transferred from one object to another.
  • The definition of temperature is a measure of the
    average kinetic energy of the atoms or molecules
    of a substance.
  • Heat always flows from areas of high temperatures
    to areas of low temperatures.

23
Energy Transfer as Heat
  • There are three different ways that thermal
    energy or heat can be transferred.
  • Conduction the transfer of heat through matter
    by molecular activity. The energy of molecules
    is transferred by collisions from one molecule to
    another.
  • The transfer of heat through metal objects is a
    good example of conduction.

24
Conduction
25
Energy Transfer as Heat
  • Convection The transfer of heat by mass
    movement or circulation within a substance.
  • Convection usually occurs in fluids, like the
    oceans and air, where the atoms and molecules are
    free to move around.
  • The earth's mantle is also believed to move by
    convection currents.

26
Convection
27
Convection
28
Energy Transfer as Heat
  • Radiation The transfer of energy (heat) through
    space by electromagnetic waves.
  • Unlike conduction or convection, radiation does
    not need a substance to travel through.
  • Radiation can travel through a vacuum or empty
    space without a medium or any substance
    containing matter.
  • The Suns warmth reaches Earth by radiation.

29
Radiation
30
Radiation
31
What happens to Solar Radiation that comes into
the Atmosphere?
  • Some solar radiation gets absorbed by atmospheric
    gases and the earth's surface.
  • Some solar radiation is transmitted through
    transparent objects like water and air.
  • When solar radiation is transmitted through
    objects, sometimes it is scattered.
  • Some solar radiation is reflected off of clouds
    and the surface of the earth.

32
Earth's Radiation Budget
33
What are some factors that affect temperatures on
the earth?
  • Factors that affect the temperature of the earth
    include factors such as latitude, proximity to
    land and water, altitude, cloud cover, and wind
    and ocean currents.
  • Water moderates temperature changes. If a
    geographic location lies close to a large body of
    water, the region will experience cooler summers
    and warmer winters compared to regions located
    farther away from a large body of water.

34
Factors influencing Temperatures
  • When cloud cover is high, the sun's solar
    radiation is reflected back into space, causing
    cooler daytime temperatures.
  • At night, the cloud cover reflects the radiation
    of the earth under the clouds back to the earth.
    This keeps the nighttime temperatures a little
    warmer.

35
What are Isotherms?
  • Isotherms are lines drawn on a map connecting
    areas of equal temperatures.
  • They are similar to contour lines, but instead of
    connecting lines of equal elevation they are
    connecting areas of equal temperatures.
  • They are useful for determining weather patterns
    and factors affecting temperature.

36
Isotherms
37
Isotherms
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