Atmosphere. Our atmosphere Earth’s atmosphere = the layer of gases that surround the planet Very thin layer, relative to size of planet Atmosphere: Absorbs.
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Slide 1
Atmosphere
Slide 2
Our atmosphere Earths atmosphere = the layer of gases that
surround the planet Very thin layer, relative to size of planet
Atmosphere: Absorbs solar radiation Burns up meteors Transports and
recycles water and other chemicals Moderates climate
Slide 3
Atmospheric composition 78% nitrogen 21% oxygen 1% argon traces
of other permanent gases and variable small amounts of: water vapor
carbon dioxide methane pollutants etc.
Slide 4
Layers of the Atmosphere The atmosphere has four layers:
Thermosphere Mesosphere Stratosphere Troposphere
Slide 5
Layers of the Atmosphere The four layers of the atmosphere
include: 1. the troposphere, where we live; 2. the stratosphere,
which contains the ozone layer; 3. the mesosphere, where meteors
burn; and 4. the thermosphere, where satellites orbit Earth.
Slide 6
Layers of the Atmosphere The atmosphere is divided into layers
based on temperature changes.
Slide 7
5.2 The exosphere and ionosphere Communication on Earth depends
on satellites. Satellites transmit information used for television
shows, radio broadcasts, data and photos used in weather reports,
and long distance telephone calls.
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Atmospheric layers Atmosphere consists of several layers:
Troposphere = bottom layer, at Earths surface; 11 km high;
temperature decreases with altitude Stratosphere = next layer up
(1150 km); temperature increases with altitude; contains ozone
layer Mesosphere = third layer up (5090 km); temperature decreases
with altitude Thermosphere = top layer (90500 km); very thin air;
mostly lightweight elements; very hot; ionic radiation
Slide 9
Atmospheric layers Temperature and other characteristics vary
with altitude. Tropopause marks boundary between troposphere and
stratosphere. Layers dont mix. Ozone layer
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Not really a layer, but a region of higher-than-normal ozone
concentrations (which are still very low) ~1730 km altitude Absorbs
ultraviolet (UV) radiation from sun, protecting organisms on
surface from radiation damage
Slide 11
Atmospheric properties Atmospheric pressure = weight per unit
area of air being pulled down by gravity (is less at higher
altitudes) Relative humidity = ratio of water vapor air contains
relative to how much it could contain at that temperature
Temperature = air is warmed by the sun; temperature varies with
altitude, location, time of day
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Pressure, density, and altitude Gravity pulls most air
molecules close to Earths surface, so air density is greatest near
the surface. Atmospheric pressure is the greatest near the surface
because most molecules are above.
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The suns energy heats the atmosphere and does so differentially
at different latitudes.
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The sun and Earths tilt create seasons
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The sun drives weather in the troposphere Solar heating
establishes convective circulation, circular currents in which warm
air rises and cool air falls.
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Composition of Atmosphere (Mixture of gases, solids, and
liquids) Early atmosphere was much different than today Volcanoes
produced nitrogen and carbon dioxide, but little oxygen More than 2
billion years ago, early organisms began producing oxygen
Eventually, oxygen formed an ozone layer that protected Earth from
harmful rays Green plants and diverse life forms developed
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Atmospheric Gases (Mixture of gases, solids, and liquids)
Nitrogen - 78% Oxygen - 21% Water Vapor 0 to 4% Used for clouds and
precipitation Carbon Dioxide -.037% Keeps Earth warm and is used by
plants to make food Argon -.93% Traces of neon, helium, methane,
krypton, xenon, hydrogen, and ozone
Slide 18
Atmospheric Gases (Mixture of gases, solids, and liquids)
Atmosphere is changing with the introduction of pollutants;
increasing human energy use is increasing the amount of carbon
dioxide Pollutants mix with oxygen and other chemicals to form smog
Aerosols include solids such as dust, salt, and pollen Liquids
include water droplets and droplets from volcanoes
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Lower Layers of Atmosphere Troposphere: lowest layer extends up
to 10km; contains 99% of the water vapor and 75% of the atmospheric
gases The troposphere is the first layer above the surface and
contains most clouds and half of the Earth's atmosphere.troposphere
Weather occurs in this layer. Most of the layers heat is from Earth
Temperature cools about 6.5 degrees Celsius per kilometer of
altitude.
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Upper Layers of Atmosphere Mesosphere extends from the top of
the stratosphere to about 85 km above Earth Coldest layer with
little ozone Meteors or rock fragments burn up in the
mesosphere.mesosphere Ionosphere here layer of charged
particles
Slide 21
Upper Layers of Atmosphere Thermosphere thickest atmospheric
layer found between 85 km and 500 km above Earths surface The
thermosphere is a layer with auroras, known for its high
temperatures.thermosphere Warms as it filters out X-rays and gamma
rays from the Sun Ionosphere here, too help carry radio waves.
Slide 22
The Ionosphere (= Thermosphere) Above mesosphere; density so
low the Space Shuttle and ISS orbit here, with little drag
Temperature can be very high; 4,000F. But no significant heat
because density is so low. Heated by ionization by UV from the sun,
and the solar wind.
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Upper Layers of Atmosphere Exosphere - The atmosphere merges
into space in the extremely thin exosphere. This is the upper limit
of our atmosphere.exosphere Outer layer where space shuttle
orbits.
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Atmospheric Pressure Molecules closer to the surface are more
densely packed (at higher pressure) together than those higher in
the atmosphere because of the mass of gases pressing down on them
from higher in the atmosphere
Slide 26
Temperature in atmospheric layers The troposphere is warmed
primarily by the Earths surface; temperature decreases as altitude
increases in this layer. Temperatures increase as altitude
increases in the stratosphere, particularly in the upper portion
ozone Temperatures decrease with altitude in the mesosphere
Thermosphere and exosphere are the first to receive Suns rays, so
they are very hot
Slide 27
The Ozone Layer About 19 km to 48 km above Earth in the
stratosphere (90%) and troposphere (10%). Layer of 3-atom molecules
that protects the Earth from the Suns harmful ultraviolet radiation
Life depends on the ozone! Pollutants called chlorofluorocarbons
(CFCs) are destroying the ozone CFCs are used in refrigerators, air
conditioners, aerosol sprays, and foam packaging ~ if products
leak, CFCs enter atmosphere Ozone layers has a large hole over
Antarctica and a smaller one over the North Pole
Slide 28
The Ozone Layer above your head, lies an atmospheric layer
called the ozone layer. Within the stratosphere, about 19 km to 48
km Ozone is made of oxygen. Although you cannot see the ozone
layer, your life depends on it.
Slide 29
The Ozone Layer An ozone molecule is made up of three oxygen
atoms bound together. The ozone layer contains a high concentration
of ozone and shields you from the Sun's harmful energy. Ozone
absorbs most of the ultraviolet radiation that enters the
atmosphere. Ultraviolet radiation is one of the many types of
energy that come to Earth from the Sun.
Slide 30
CFCs Evidence exists that some air pollutants are destroying
the ozone layer. Blame has fallen on chlorofluorocarbons (CFCs),
chemical compounds used in some refrigerators, air conditioners,
and aerosol sprays, and in the production of some foam packaging.
When a chlorine atom from a chlorofluorocarbon molecule comes near
a molecule of ozone, the ozone molecule breaks apart. One of the
oxygen atoms combines with the chlorine atom, and the rest form a
regular, two- atom molecule.
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CFCs
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These compounds don't absorb ultraviolet radiation the way
ozone can. In addition, the original chlorine atom can continue to
break apart thousands of ozone molecules. The result is that more
ultraviolet radiation reaches Earth's surface. Chlorofluorocarbon
molecules destroy ozone. By October, the ozone concentration
reaches its lowest values and then begins to increase again. By
December, the ozone hole disappears.
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The Ozone Hole The destruction of ozone molecules by CFCs seems
to cause a seasonal reduction in ozone over Antarctica called the
ozone hole. Every year beginning in late August or early September
the amount of ozone in the atmosphere over Antarctica begins to
decrease.