Transcript The Earth`s Atmosphere

The Earth’s Atmosphere
6.6 The student will investigate and
understand the properties of air and the
structure and dynamics of the Earth’s
atmosphere.
SOL 6.6a
Air is a mixture of gaseous elements
and compounds.
• The atmosphere is a mixture of many gases,
dust and more additional materials than you can
imagine.
Elements
• Approximately 78% of the air is nitrogen. (N2)
• Approximately 21% of the air is oxygen. (O2)
• Argon and other gases make up about 1%
Argon and other gases make up
the remaining 1% of our air.
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Argon
Carbon Dioxide
Neon
Helium
Methane
Krypton
Hydrogen
0.93 %
0.036 %
0.0018 %
0.00052 %
0.00015 %
0.00011 %
0.00005 %
Air contains gaseous compounds.
• Carbon and oxygen combine to form CO2
• Nitrogen and oxygen form nitrogen dioxide
NO2
• Hydrogen and oxygen combine to form
H2O ( water vapor ).
Argon and other gases 1%
Oxygen
21%
Nitrogen
78%
Air contains many other ingredients!
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Millions of tons of particles and polluting gases…
Particles from volcanoes
Salt grains from ocean spray
Dust from meteors
Sand from desert storms
Soot from fires
Rubber vaporized from car tires
Pollen from plants, bacteria, spores from fungi
Chemicals from fertilizers and pesticides
Dust and other human wastes
Carbon monoxide (CO) Emissions from vehicles
Photochemical Smog
• Smog is a thick, brownish haze formed
when certain gases in the air react with
sunlight.
• Major sources of smog are the gases
emitted by automobiles and trucks.
• These gases, (hydrocarbons and nitrogen
oxides, react in the sunlight, forming
ozone (O3). The major, toxic chemical
found in Smog.
Acid rain
• Another type of pollution caused by power
plants and factories, that burn coal and oil
• These fuels produce nitrogen oxides and
sulfur oxides when burned.
• Nitric acid and sulfuric acid are created
when these gases react with water vapor.
• These acids return to Earth, dissolved in
precipitation, as acid rain. (ph may be 4.0)
Properties of Air
• Air has mass – air is made up of atoms, and
molecules.
• Air has volume - takes up space.
• Air has density – mass/volume
• Air has pressure – the weight of a column of air
pushing down on a surface or area
Air Pressure
• Air pressure is measured with a barometer. The
barometer may be a mercury barometer or an
aneroid barometer.
Altitude and air pressure
• Air pressure decreases with altitude –
there is less air pressure on the top of a
mountain that at sea level.
• The density of air also decreases with
altitude. (More difficult to breathe at high
altitudes)
Layers of the Atmosphere
The four main layers of the atmosphere are
classified according to changes in
temperature.
These layers are the Troposphere, the
Stratosphere, the Mesosphere, and the
Thermosphere.
Troposphere
• The layer of the atmosphere closest to the
Earth’s surface
• We live in the troposphere
• Nearly all of the Earth’s weather occurs in this
layer
• Contains 80 % of the atmosphere’s mass
• Contains 99 % of the atmosphere’s water
• Tropopause separates this layer from the
stratosphere
Troposphere continued
• The height of the troposphere varies from 16km to 19km above the
equator and 9km to 10km above the North and South poles.
• The temperature at the bottom of this layer (The Earth’s surface)
averages 15° Celsius (59° Fahrenheit)
• As the altitude increases in the troposphere the temperature
decreases. On average each 1km increase in altitude results in a
temperature drop of 6.5° Celsius, until it remains constant at about
-60° Celsius.
• Water at the top of the troposphere forms thin, feathery, clouds of
ice.
• The Tropopause separates this layer from the stratosphere
The Troposphere affects our
weather.
• Temperature variations within this layer help
create our weather.
• Colder, denser air sinks, forcing warmer, less
dense air to rise. Rising air expands and cools.
Water vapor may condense and form clouds and
possibly precipitation.
• Sinking air is compressed and warms. In this
warmer air, clouds may vaporize or fail to form,
resulting in fair weather.
Stratosphere
• The stratosphere begins at the top of the
troposphere.
• The stratosphere begins at about 10km (6
miles) above the Earth’s surface at the poles.
• The stratosphere begins at about 19km (12
miles) above the Earth’s surface at the Equator.
• The upper boundary, the stratopause, reaches
up to about 48km to 50km (30 miles).
Stratosphere continued,
• The temperature in the lower level is
steady at approximately - 55° Celsius to
-60° Celsius (- 167° Fahrenheit).
• The upper layer is warmer, reaching
approximately -2° Celsius (28° Fahrenheit)
• Ozone in this upper region, absorbs
harmful, ultraviolet radiation from the sun.
Ozone in the stratosphere
• Ozone (O3) absorbs this light and
converts it into heat. This is why the upper
region of this layer is warmer.
• About 80 to 90% of the ozone in the
atmosphere is found in the stratosphere.
Ozone data:
compliments of a sixth
grade student
• Ozone can aggravate asthma
• Ozone can cause reduced lung function,
inflame chronic lung disease and cause
permanent damage to lungs
• Prevention of exposure includes reducing
outdoor activities
Stratosphere and weather
• Strong, complex winds, known as the jet
stream are located in the boundaries
between the stratosphere and the
troposphere.
Stratosphere and weather
• The stratosphere is extremely dry, nearly
cloudless, and weather does not occur
there. Ice clouds however, do form above
the polar regions in the winter time.
Stratosphere and weather
• Weather balloons rise into the
stratosphere before they burst, allowing
their instrument packages to fall back to
Earth.
Mesosphere Location
• The mesosphere begins at an altitude of
about 48 to 50 km (30 miles) above the
Earth’s surface, and extends to about 80
km (50 miles), upward.
Mesosphere temperatures
• A drop in temperature above the
stratosphere, marks the beginning of the
mesosphere.
• Temperatures decrease as you go higher
in the mesosphere, reaching -90° to -109°
Celsius
(-165° Fahrenheit).
Mesosphere
• The mesosphere protects the Earth from
meteorites, chunks of rock and metal from
space, as they usually burn up upon
entering this layer.
• “Shooting stars,” or meteors, leave a trail
of burning gases that are often seen in this
part of the atmosphere.
Thermosphere
• The thermosphere begins at the mesopause, the
uppermost boundary of the mesosphere at
about 80 km (50 miles) and continues into space
• It has no definite outer edge. Gas atoms and
molecules there are so far apart that the air
blends gradually with outer space, (1000+
kilometers or 620+ miles, above the Earth).
Thermosphere Continued
• The air at the upper boundary of the
mesosphere is very thin. Imagine one
cubic meter of air at sea level, being
expanded to 100,000 cubic meters at the
mesopause.
• The air in the thermosphere is even
thinner.
Thermosphere Composition
• Molecules of nitrogen (N2) and atoms of
Oxygen (O) make up most of the lower
parts.
• At about 200km (125 miles) Oxygen atoms
begin to outnumber nitrogen molecules.
• Above 1000Km (620 miles) the
thermosphere contains mainly Hydrogen
and Helium.
Thermosphere Temperature
• The thermo in thermosphere means
“heat.”
• Air temperatures rise steadily with altitude.
• The temperature rises from about -90°C
(-130°F) at an altitude of 80 Km, to more
than 1200°C (2200°F) at about 350Km
(220 miles).
Thermosphere absorbs heat
• The upper region of the thermosphere, the
exosphere, absorbs more radiation from
the sun.
• Changes in solar activity cause the
temperatures in the thermosphere to vary
more than any other layer.
Heat is not transferred
• High temperatures result from rapid
movement of the atoms and molecules.
• Because the atoms and molecules are
spaced so far apart, their movement is not
recorded on ordinary thermometers.
(Temperature would appear to be well
below 0° Celsius).
When is 2200° Fahrenheit cool?
• You would not feel warm in the
thermosphere.
• Satellites and other spacecraft also stay
cool in this layer because the air is too thin
to transfer much heat.
Thermosphere divided in two…
• The thermosphere is divided into two parts
• The lower layer, the Ionsphere, begins at
about 80 Km above the Earth’s surface,
and continues up to about 550 Km.
• Energy from the sun causes gas
molecules to be come electrically charged
particles called Ions.
Ionosphere
• Radio waves bounce of the ions and then
bounce back to the Earth’s surface,
allowing us to communicate.
Ionosphere
• The Northern Lights, (aurora borealis) also
occur in the Ionosphere.
• Particles from the sun enter the
ionosphere near the North Pole, striking
Oxygen and Nitrogen atoms, causing them
to glow.
Exosphere
• Exo- means “outer,” so the exosphere is
the outer layer of the Thermosphere.
• The exosphere extends from about 550
km above the Earth’s surface, outward for
1000’s of km to outer space.
Satellites in the Exosphere
• Satellites traveling in the exosphere are
used for transmitting signals used for cell
phones, television, tracking the weather
and carrying telescopes to look into space.