Transcript The Atmosphere and Space

The Atmosphere
and Space
Chapter 7
• What brought the jumper to the ground?
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.
• Air: the mixture of gases that make up the
atmosphere
Role of the atmosphere
Ensures stable climate
by retaining heat
Blocks harmful
UV rays
Gases for cellular
respiration
Gases for photosynthesis
1.1 The Composition
of the Atmosphere
0.93%
0.04%
H2O (0 to 4%)
21%
78%
+ particulate matter (smoke, dust, pollen, etc)
Atmospheric
Layers
Characteristics of Each Layer
•
Troposphere – 0-15 km
• As altitude rises, temperature drops (6.5°C per km)
• Layer where clouds and storms form
•
Stratosphere -15-50km
•
as altitude rises, temperature rises due to the ozone layer
• Fewer air particles as altitude rises
-------------------------OZONE LAYER ------------
•
Mesosphere – 50-80km
•
coldest layer (as altitude rises, temperature drops)
• Very few air particles
Characteristics of Each Layer
• Thermosphere 80-500km
• hottest layer because it absorbs
most of the sun’s rays
• Shooting stars (meteors burning)
and polar auroras formed
• Exosphere 500km+
• Air particles rare – fairly empty
•
Where satellites orbit
Atmospheric Pressure and
Temperature
• Atmospheric Pressure: the forces of air molecules
colliding with each other.
• Unit of measurement: Kilopascals
• Symbol: kPa
• Measured by barometer
Factors affecting
Atmospheric Pressure
• # air particles
increases
•
more collisions,
more pressure
• #air particles
decreases
•
less collisions,
less pressure
Factors affecting
Atmospheric Pressure
• Temperature increase
• Particles move faster, collide more
• Stuck in a closed jar this would create a lot of
pressure
• BUT we are not in a jar, particles collide and move
away from each other
• Warm air rises, becomes less dense and therefore
LESS pressure
• Temperature decrease
• Particles move close together and cool air falls
• Pressure increases
• When preparing to climb mountains
such as Mount Everest (8.8 km
from sea level), climbers must train
hard to increase their
cardiovascular fitness. Some also
choose to train with high altitude
masks. Why?
Altitude &
Pressure
• High altitude = less air =
low pressure
• Low altitude = more air =
more pressure
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.
Video 1
Video 2
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
• 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
• Warm front: formed when a warm air mass
rises as it moves toward a cold air mass.
• Creates light nimbostratus clouds (stratified).
• Showers slow to disperse
Depressions 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. (B)
• In an anticyclone the sky is clear because
falling air does not promote the formation
of clouds. (A)
Weather + Anticyclones and
Depressions
• H / Anticyclones / high pressure =
clear sky, dry, stable
• L / Depressions / Low pressure =
clouds & precipitation
L
H
Video
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.
Video
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
Nitrous Oxide N2O
• Released through:
• chemical processes
• Applying nitrogen rich fertilizer to crops
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.
OH wait...
That just happened!!
“As of Thursday morning, it appears that
average temperatures across the Northern
Hemisphere have breached the 2 degrees
Celsius above “normal” mark for the first
time in recorded history, and likely the first
time since human civilization began ...”
March 3, 2016
February obliterated the all-time global
temperature record set just last month.
(February 2016)
1.5 Energy Resources
• Wind energy: energy
that can be drawn
from wind.
• Mechanical to
electrical
• Video
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 and 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