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Atmosphere
The atmosphere is that layer of air that surrounds the Earth. It protects is from solar radiation. It
provides living things with gas that they need to live (ex: CO2 for plants, Oxygen for humans & animals).
The atmosphere maintains a temperature on the earth so live can exist. Without the atmosphere the
temperature on earth would be -18oC.
99% of the gases are in the first 30km above the surface of the Earth. The Atmosphere extends more
than 10 000km.
The atmosphere is composed of:
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78% nitrogen
21% oxygen
The other 1% is composed of all the other gases (0.38% CO2, 0.4% water vapor, 0.000 001%
Ozone etc…)
Atmospheric Pressure
Gravity pulls the gases towards Earth. Because of gravity most of the air molecules are close to the
earth, therefore there’s a higher pressure at a lower altitude.
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The higher into the atmosphere you go, the less air molecules therefore the lower the pressure.
The pressure at the surface is 14.7 pounds whereas at the top of Mount. Everest the pressure is
4.5
Layer of the Atmosphere
1. Troposphere:
 From the surface 10-15km
 Most clouds and storms occur in this layer
 The temperature drops with altitude (the higher up you go, the temperature is colder
in this layer)
 Where weather happens
 Contains most of our air
 Contains all life
 Where planes fly
2. Stratosphere:
 15-50km
 Is the ozone layer
 It contains all the ozone which absorbs UV rays
 Protects us from these rays
 As you go up in this layer, the temperature gets hotter due to the fact that is absorbs
the UV rays
3. Mesosphere:
 50-80km
 Contains meteors
 Contains stars
 Contains very little air particles
 It’s very cold
4. Thermosphere:
 80-500 km
 It is the hottest layer in the atmosphere (up to 2000 degree) because it absorbs fmost
of the sun’s radiation but it would not feel hot to us because of the rarity of air
particles
 Contains the Aurora borealises
5. Exosphere:
 500-10 000km
 Its empty, outer space
 Satellites orbit earth in this layer
Atmospheric Circulation
It is driven by the rotation of the earth & convection.
Convection warm air at the equator rises and travels to the poles. Cold air moves south closer to the
surface.
The combination of convention & the Earth’s rotation causes the Coriolis effect. Air moves in curved
paths.
Predicting weather
There is a fair amount of randomness when
predicting weather this is called the
Butterfly effect.
 Air circulates in loops. These loops
are called cells. There are three cells called:
Hadley, Ferrel & Polar. The Hadley cell
spans the equator. The Ferrel cell circulates
over Canada & the States. The Polar air
transports the coldest air and is near the
poles.
 The circulation is driven by the rising of warm of air and the sinking of cold air (convection)
 Prevailing winds (polar easterlies, westerlies & the trade winds) are created and they move in
predictable directions based on the Coriolis effect.
(longitudes horizontal, latitudes vertical)
Trade winds are easterly (east to west), from the
equator, NEAR the equator. Westerlies blow from
the west to the east. Polar easterlies blow from the
east to the west.
Air Masses
Large volumes of air that are uniform temperature (1-2o F) and humidity are called air masses. Quebec
receives warm, moist air masses from the south & cold, dry air masses from the North.
When two air masses meet, a Front is created. When cold air is moving there is a cold front and when
warm air is moving there is a warm front. Remember that a cold front is dense, therefore it pushes the
warm front up.
Cold front cold air pushes the warm air up. The warm, moist air condenses resulting in rain &
thunderstorms. They are represented with blue line with arrows
Warm front warm air slides over a cold front causing precipitation. Represented with a red line with
semicircles.
Anticyclones & Depressions
They are caused by the rise and fall of vertical air.
 When warm air rises a depression is created. Depression is the low air pressure left behind when
warm air rises. Depression is basically the rain and wind before a cyclone…depressions could
become hurricanes
 Convection currents form around the rising air in hurricanes & the earth’s rotation is what spins
a hurricane. (wind can be over 350km/h & the diameter of the hurricane can be over 1500km)
Anticyclone (high pressure zone). Created when cold air drops vertically. It is associated with blue skies
that are sunny and clear. (represented with a H)
High pressure brings moist, warm, sunny weather. Low pressure brings rainy, dry, cold weather (even
hurricanes, tornadoes….)
The Greenhouse Effect
Most of the Sun’s rays that reach the Earth’s surface are absorbed by the ground. The ground emits
infrared rays that get trapped into the atmosphere while others get lost in space. Greenhouse gases
retain some of these rays and retransmit them back to Earth.
Water vapor, Carbon dioxide, Methane & Ozone contribute the most to the greenhouse effect.
 The Greenhouse effect makes Earth’s climate liveable but…. As more greenhouse gases are
being emitted in to the air, Earth’s climate is getting warmer which will cause many problems
(glaciers melting, sea levels rising, floods, more skin cancer cases)
 CO2: emitted from burning fossil fuels & cutting forests
 Methane: released from cow farts & decomposing waste
 Nitrous oxide: emitted by nitrogen rich fertilizers
 CFC: destroy the ozone layer
Nitrogen & Sulfur dioxide cause acid rain. Metals such as mercury are harmful for humans.
Earth’s temperature has risen by 0.76oC in the last 150 years and it is said that a rise of 2o in
temperature will cause environmental problems.
CFCs were used in arsenols & refrigerators. When these gases are emitted into the atmosphere they
destroy ozone by releasing chlorine. The Ozone Layer is thinning which is a huge problem because it
blocks the ultra violet radiation from the sun, this radiation can cause damage to living things (skin
cancer). In 1987 CFCs were banned.
Smog
Ozone is good and bad. It is good because it absorbs UV rays but if too close to the surface ozone can be
harmful.
 Pollution from industries & vehicules (nitrogen oxide) reacts with the sun’s rays to form ozone,
close to the surface of the Earth. When ozone is mixed with smoke and fog it creates smog.
Smog can cause lung damage.
Energy from Air
 Wind energy: wind is a renewable source. Energy from the wind can be captured by wind
turbines. A wind turbine produces 2 megawatts of power which is enough to supply 2000
houses. The only problem is that the wind is not constant therefore a combination of energy
types will be needed.
Effect of the Sun & Moon on Earth
The sun is created of hydrogen (78%) & helium (25%). Gravity and nlucear fusion at its core turns the
hydrogen into helium (which produces the sun’s rays). Energy from the sun is electro-magnetic.
Because the Earth is curved (in the shape of a circle) the sun rays heat the surface unevenly. This
difference drives the circulation of the hydrosphere & atmosphere. (causes wind)
Ways to capture solar energy: passive heating, solar panels & solar collectors.
Passive heating the sun rays heat up “heat sinks” (concrete, walls). These heat sinks heats up a space
at night.
Solar panels when sun rays hit sillicons, electrons flow. (can power appliances, or charge batteries)
Solar collectors flowing water or in oil in pipes collect’s the suns heat. This heat is then transferred to
another location. ( ex: to heat up swimming pools)
The Moon
Created 4.6 billion years ago when Theia hit Earth. The Moon and the Earth have a gravitational pull
between each other, which causes the Earth and its water to always lean towards the moon. When
water is leaning towards the moon, it creates tides. There are atleast two high and two low tides per
days.
 When the sun is in line with the moon it adds to the effect the moon has on Earth (high tides)
 When the sun is at right angles of the moon it reduces the effect the moon has on Earth (low
tides)
 The energy of tides can be used to generate energy (tidal energy captured by tidal turbines)
REVISION
The Cryosphere
It includes all the frozen water on Earth’s surface.
 Glacier, snow, icebergs
 Sea ice
Pack Ice: Pack ice expands & contracts. It is a seasonal change. Pack ice is basically frozen ocean
surfaces. Pack ice break off into huge pieces and become ice floes. The extent of pack ice decreased
(because of global warming & increasing carbon dioxide levels)
Glaciers: Buildup of snow on land at the poles. The pressure turns the snow into ice. Many of the
glaciers have been melting. As they melt they slide off the land and could rise sea levels. They can also
disrupt the thermohaline circulation, which can mess up Earth’s climate.