Transcript The Atmosphere and Space

The Atmosphere
and Space
Chapter 7
Outline
• 1. The Atmosphere
• 1.1 The composition of the atmosphere
• 1.2 Atmospheric Circulation
• 1.3 The Greenhouse Effect
• 1.5 Energy Resources
• 2. The Effect of the Sun and the Moon on
the Earth
• 2.1 Solar Radiation
• 2.2 The Earth-Moon System
1. The Atmosphere
• Atmosphere: the layer of air surrounding the
Earth.
The gases of the atmosphere
Ensures stable climate
Gases for cellular
respiration
Blocks harmful rays
Gases for photosynthesis
Earth’s gravitational force
• Most of the
mass (particles)
of the
atmosphere is
concentrated
within 30 km
above the
ground because
of Earth’s
gravitational
force.
1.1 The Composition of the
Atmosphere
• Air: a mixture of gases, especially nitrogen
and oxygen, that makes up the atmosphere.
0.93%
0.04%
H2O (0 to
4%)
21%
78%
Atmospheric Pressure and
Temperature
• Atmospheric Pressure: the
forces of air molecules
pushing against each other.
• As the altitude increases, the
pressure decreases (fewer
particles = fewer collisions)
and the temperature
fluctuates.
• As the altitude decreases, the
pressure increases (more
particles = more collisions)
and the temperature
fluctuates.
Atmospheric Layers
• A) Troposphere
• B) Stratosphere
• C) Mesosphere
• D) Thermosphere
• E) Exosphere
Characteristics of Each Layer
• A) Troposphere: as altitude rises, temperature
drops. Layer where clouds and storms form.
• B) Stratosphere: as altitude rises, temperature
rises because of the ozone layer.
• C) Mesosphere: coldest layer (as altitude rises,
temperature drops) + few particles of air.
• D) Thermosphere: hottest layer because it
absorbs most of the sun’s rays.
• E) Exosphere: very few particles, where satellites
orbit.
1.2 Atmospheric Circulation
• Atmospheric circulation: global-scale movement
of the layer of air surrounding the Earth.
• Hot air rises (low density)
• Cold air falls (high density)
• Air warmed at the equator rises and moves toward
the poles. Cold air from the poles is more dense and
moves toward the equator = CONVECTION
Air Movement
• Wind in the Northern
Hemisphere appears to move to
the right.
• Wind in the Southern
Hemisphere appears to move to
the left.
• This is a consequence of the
Coriolis effect.
Air Masses
• Air mass: large
expanse of the
atmosphere with
relatively uniform
temperature and
humidity.
• Québec is affected by
cold air masses from
polar regions and
warm air masses from
the tropics.
When cold and warm meet
• When two air masses meet:
• They move horizontally
• They don’t combine
• Cold air is denser and sinks under the warm air
• The border where they meet is called a front.
A front is a zone of transition where the direction of
the wind, the temperature and relative humidity
can change rapidly.
Cold front
• A) cold front: formed when a cold air mass
meets a warm air mass.
• Warm air rises rapidly and then cools 
forms puffy clouds = cumulus.
• Heavy rain and wind.
Warm front
• B) warm front: formed when a warm air
mass rises as it moves toward a cold air
mass.
• Creates nimbostratus clouds (stratified).
• Slower than a cold front because it is less dense.
Cyclones and Anticyclones
• Air masses can also move vertically.
• Anticyclone: Symbol is H (high
pressure)
• cool air particles collide infrequently
• the particles are closer together
• the density is high = particles fall to the ground and
create an area of high pressure.
• Depression: Symbol is L (low pressure)
• Warm air particles collide frequently
• low density
• The air mass rises creating a space of low
pressure beneath it.
Air masses and Coriolis Effect
• As the air rises or falls it starts
to rotate according to the
Coriolis Effect.
• In the northern hemisphere:
anticyclones rotate clockwise and
depressions rotate counterclockwise.
• In the southern hemisphere:
anticyclones rotate counterclockwise
and depressions rotate clockwise.
Weather + Anticyclones and
Depressions
• In a depression rising air encourages the
formation of clouds.
• In an anticyclone the sky is clear because
falling air does not promote the formation
of clouds.
L
H
Strong depressions + water
• A cyclone forms when strong depressions
form over warm waters of tropical oceans.
• Cyclone: tropical storm characterized by violent
winds revolving around an area of low pressure.
• The spiral storm can stretch over 1000 kilometers
with winds.
• Cyclone = hurricane = typhoon
1.3 The Greenhouse Effect
• Greenhouse effect: natural process that
allows the Earth to retain some of the heat
it receives from the Sun.
Atmospheric gases behave like
the greenhouse glass
 Most of the sun’s rays
that reach the Earth’s
surface are absorbed
by the ground.
 The heated ground
emits infrared rays
(heat):
 the rays can exit the
atmosphere and are lost
in space.
 the rays can be
trapped by the
greenhouse gases which
heats the surface
furthermore.
Greenhouse gases: Then & Now
Then and Now
• Then: CO2 was mainly emitted from forest
fires, volcanic activity and cellular
respiration. CO2 was absorbed through
photosynthesis and oceans.
• Natural balance
• Temperature is relatively stable.
• Now: CO2 emissions are increased because of
combustion reactions from fossil fuels.
• Billions of tonnes are released into the atmosphere
because of human activity.
Increased CO2 & decreased O2
• Increased levels of CO2:
• Burning forests to clear land (combustion)
• Decreased levels of O2:
• Deforestation (reduced photosynthesis)
Global Warming
• More CO2 emitted in the atmosphere =
more heat trapped within the atmosphere.
• This phenomenon is called global warming and
leads to changes in climate.
• Climate change: the abnormal
modification of climatic conditions
on Earth, caused by human activity.
Other GHG (greenhouse gases)
• Methane and nitrous oxide are also emitted
in higher concentrations but their effect is
not as great as that of carbon dioxide.
If methane = carbon dioxide
• If methane was emitted in equal
concentrations as carbon dioxide it would
have an effect
warming.
•
21 times greater on global
Methane gas
emission sources:
• Digestions in
farm animals
• Manure storage
• Household waste
decomposition
• Rice farming
Temperature on the rise
• From 18502005 = average
temperature
rose by 1oC. If it
rises by another
degree = more
droughts, heat
waves and
floods + rise in
sea levels.
1.5 Energy Resources
• Wind energy: energy that can be drawn
from wind.
• Mechanical to electrical
Wind energy pros and cons
• Advantages:
• Wind is a renewable energy
• No GHG produced
• Disadvantages:
• Ruins the beauty of the landscape
• Can’t predict wind (when or how it blows)
• Cannot be stored (must combine with other source
of energy – usually a dam)
2. The Effect of the Sun and
the Moon on the Earth
2.1 Solar Radiation
• Nuclear reactions
of the Sun
transform
hydrogen into
helium which in
turn produces
energy.
• Solar energy is
radiated across
the solar system
and reaches Earth
in 8 minutes.
Solar radiation
• Solar radiation contains all the waves in the
electromagnetic spectrum.
Only some reach Earth
• Only visible light, radio waves, some infrared
rays and some ultraviolet rays reach Earth’s
surface.
• These rays heat the atmosphere, the oceans and the
land.
• Equatorial regions are hotter because they receive more
solar energy due to Earth’s shape and orientation.
Solar energy
• Solar energy = energy that comes from the sun
in the form of radiation through the
atmosphere.
• Technologies that take advantage of solar
energy:
• Passive heating systems: position houses in such a way
as to capture as much light and heat possible.
• Photovoltaic cells: silicon in these “cells” is activated
by light and set electrons in motion creating an
electric current. (solar panels = large concentration of
photovoltaic cells)
• Solar collectors = large glass panels that capture heat
from sunlight and transfer that heat to water in
copper pipes just below the panels.
2.2 The Earth-Moon System
• The moon revolves around the Earth and
rotates on its own axis.
• Rotation and revolution of the moon: 27.3 days.
Tides
• A gravitational pull of the Moon and the Sun
is responsible for daily tides on Earth.
• Tide: the rise and fall of water in the seas and
oceans. It is caused by the gravitational force
of the Moon and, to a lesser extent, the Sun.
• The water bulges in the direction of the Moon.
The opposite side of Earth
• Why does the
opposite side of the
Earth also experience
simultaneous tides?
• The water is less
attracted to the
Moon than the Earth
itself is, so the Earth
is drawn away from
the water, toward
the Moon.
Spring and Neap Tides
• Twice each month, at the time of the new
moon and the full moon, the gravitational
influences of the moon and sun reinforce one
another and cause the tides to rise to
greater heights and fall lower than average
tides. These are called spring tides
• At the time of the quarter moon, when the
sun, earth, and moon form a right angle,
the difference between high and low tide is
less than average. These are neap tides.
The Bay of Fun…..dy!
• The difference in water levels at low and
high tide is called the tidal range.
• The Bay of Fundy (near Nova Scotia) has
tides with a range of up to 17 meters.
• http://www.youtube.com/watch?v=5W2sM1
Ma7YA
Tidal Energy
• Tidal energy: the energy obtained from the
ebb and flow of tides.
• When the tide comes in it fills a water basin.
When the tide goes out it creates a
difference in water level between the basin
and the sea.
• When a gate is opened, the water in the
basin is released to flow through a turbine
which generates an electric current.
Tidal energy
• Advantages
• Renewable energy source
• No GHG
• Reliable because tides are predictable according to
the positions of the Sun and the Moon.
• Disadvantages
• Costly installation
• Few places with high tidal range