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UNIT 4: Energy Flow in Global Systems
Chapter 10: Solar Energy and Climates
Chapter 11: Climate and Biomes
The Biosphere: The thin layer of air, land, and water where all life on Earth exists.
The biosphere can be divided into 3 main parts:
1. The Atmosphere
2. The Lithosphere
3. The Hydrosphere
1. The Atmosphere: (Air) Nitrogen and oxygen make up over 90% of the Earth's
atmosphere. The atmosphere extends 800Km above the Earth's surface and is
divided into several layers. We will only be looking at the two lower layers where
the majority of the atmosphere is concentrated. These two layers are:
 The Troposphere: (0-12km above the Earth)
 The Stratosphere: (13-50km above the Earth)
2. The Lithosphere: (Land) The Earth's crust is composed of continental crust
above sea level, as well as oceanic crust at the bottom of the ocean. The Earth's
crust, along with the uppermost part of the mantle makes up the lithosphere.
The lithosphere varies in thickness from 100km to 200km.
3. The Hydrosphere: (Water) The Earth's surface is 70% water. Water in oceans,
lakes, rivers, streams, underground reservoirs, as well as in the atmosphere make
up the hydrosphere. Clouds are suspended water droplets found mostly in the
troposphere. The cryosphere is the water on Earth temporarily frozen in polar ice
caps, snow, permafrost, and glaciers.
 In order for life to exist on Earth, its temperature must remain relatively
constant.
 The hottest temperature ever recorded on earth was 56.7 C in Death
Valley California!
 The coldest temperature ever recorded was -89.4 C in Antarctica!
Brrrrrrrrrrrrrr!
The Hydrologic Cycle:
 The total amount of water vapor in the air is enough to cover the Earth with
a laver of water 2.5 cm deep.
 The hydrologic cycle carries energy as well as water. Thermal energy is
required for evaporation to occur. The thermal energy is released back into
the environment when it condenses to form rain or snow.
1. Evaporation:
 Energy from the sun is used to convert surface water to water vapor.
 Evapotranspiration is the evaporation of water from plants and the soil.
This process contributes about 10% of the water entering the atmosphere.
2. Condensation:
 Water vapor in the atmosphere rises and releases its heat to the colder air
aloft. As the air cools or if it becomes over saturated with water vapor it
condenses to form clouds.
 Dust, smoke, sea salt and other small particles provide a surface for water
molecules to collect, forming water droplets or ice crystals.
3. Precipitation:
 When the condensed water drops become too heavy they fall to the
ground as rain, snow or hail.
 Precipitation does not always fall straight down. Sometimes air currents
carry water droplets upwards where they combine with other water
droplets becoming larger.
 Strong updrafts can produce large raindrops and hail stones.
 Each time a hailstone is carried upwards it receives a new coat of moisture
and the hailstone grows until it heavy enough to fall to Earth.
 Precipitation accumulates in rivers, streams and lakes or seeps into the
ground where it collects in large underground aquifers.
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Now do check your understanding on p. 387 #1-5
Oceans and Heat Distribution
 The Oceans act as very large heat reservoirs.
 Water's low albedo allows it to absorb more than 90% of the energy that
strikes it.
 Water has a high heat capacity and high heat of fusion and vaporization.
Therefore a great deal of energy is required to make water change
temperature or state.
 70% of the Earth's surface is covered by ocean.
 Oceans are considered heat reservoirs for the entire planet because they
change temperature much more slowly than the atmosphere or land.
Ocean Currents
See figure 10.17 on p. 388
 Ocean currents are caused by primarily by surface winds but are also
affected by convection, differences in salinity, the Earth's rotation, as well
as the contours of the ocean bottoms
 Ocean currents distribute solar heat from the tropics to higher latitudes.
 The Gulf Stream is a surface current that starts in the warm, shallow seas of
the Caribbean. It follows the coastline of the United States and Canada and
ends up near the British Isles where it is called the North Atlantic Drift. The
Gulf Stream is so warm that tropical fish have been caught of the coast of
Boston and New York!
 The Gulf Stream is part of a global ocean current called the Thermohaline
Circulation or "The Great Ocean Conveyor Belt".
El Nino and La Nina
 El Nino is a disruption in the ocean-atmosphere system in the tropical
Pacific. It typically occurs every 3 to 7 years.
 During an El Nino year the wind direction over the South Pacific reverses
and flows eastward. It is not known what causes this change in wind
direction.
 The change in wind direction increases the sea surface temperature in the
equatorial Pacific Ocean.
 The warmer temperatures in the East cause drought conditions throughout
Southeast Asia and Northern Australia and heavy rainfall over the West
coast of South America.
 In North America El Nino produces milder winters, however most of the
impacts of El Nino are negative including floods, drought, and famine.
 La Nina is the result of increased westward moving winds above the South
Pacific.
 This results in the cooling of surface waters in the equatorial Pacific.
 La Nina produces wetter than normal conditions.
 In North America cold air from Alaska moves south over Western Canada
and the United States causing cooler temperatures in Western Canada and
the States. In contrast, Eastern Canada and the Eastern States become
warmer during a La Nina year.
Patterns of Wind Movement:
 Prevailing: means "happening most of the time".
 Westerlies come from the West; Easterlies come from the East, etc.
 Air is heated at the equator and rises. The expanding, rising warm air
creates an area of low pressure.
 Cool air moves in from the poles to replace the rising warm air. The cold air
contracts, forming a high-pressure system.
 The warm air aloft flows towards to poles completing the convection
current. This process distributes atmospheric heat throughout the world.
(See figure 10.19 on p. 390)
 As the warm air moves towards the poles it cools, becoming more dense
and begins to sink before it reaches the poles.
 Air descends at three different latitudes in each hemisphere:
o 30 (N and S)
o 60 (N and S)
o and at the poles
(See figure 10.20 on p. 391)
The Coriolis Effect
 As the Earth rotates its atmosphere rotates with it at the same speed.
 Moving objects along the Earth's surface, including air currents, tend to
veer sideways off their original course.
 The Coriolis effect applies to both air and ocean currents, as well as
airplanes, space shuttles and guided missiles.
 As the Earth rotates eastwards on its axis, the equator rotates much faster
than the poles.
 In other words the Earth actually rotates more slowly above 30 N and
bellow 30 S.
(See figure 10.21 on p.391)
 Air currents moving northward from 30 N to 60 N veer eastwards because
they maintain their greater eastward rotational speed as they pass over the
more slowly rotating Earth above 30 N.
 These east blowing winds are called prevailing westerlies because they
come from the West.
 Air currents moving southwards from 30 N latitude from the equator veer
to the west.
 As the air moves towards the faster rotating equator it falls behind and
veers west creating the prevailing easterlies.
(See figure 10.22 on p.392)
Jet Streams
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Currents of extremely fast moving air 10 - 15 km above the Earth.
Generally flow from west to east in both hemispheres.
Jet steams form at the boundaries of warm and cold air masses.
Jet streams are faster and larger in the winter.
Prevailing westerlies and polar easterlies in Canada converge to form the
polar jet stream. The resulting convection current is intensified by the
Coriolis effect and the air current picks up speed.
 Jet streams greatly influence precipitation and climate.
(See figure 10.23 on p.393)
Oceans and Mountains Influence Climate
 When moist air cools it cannot hold as much water. The water then
condenses and falls as precipitation.
 The BC side of the Rocky Mountains receives much more precipitation that
the Alberta side. Here's why . . .
 Warm, moist air from the coast rises up the west side of the Rocky
Mountains and cools. The moisture is then released as orographic
precipitation.
 The now relatively dry air moves down the west slope of the mountain and
into Alberta. As the air moves downwards the pressure increases warming
the air, thus leaving little chance for precipitation. A mountain region that
receives little rain is said to be in the rain shadow.
Read p. 393-395 and describe the conditions necessary for:
1. A sea breeze:
During the day, the sun warms the land along the coast and the ocean.
The land heats up much more quickly than the water because of water's
high heat capacity. As a result, the air above land becomes warmer than
the air above the water. The warmer air above land rises and the cool air
above the ocean moves in to replace it, creating a sea breeze.
2. A land breeze:
At night the land cools much quicker than the water. The air above land
quickly becomes much cooler than the air above the ocean and sinks.
The relatively warmer air above the ocean rises and the cool air moves
out to sea to replace it.
Specific Heat Capacity:
 The amount of heat required to raise the temperature of 1 g of a substance
by 1C.
 Each substance has its own specific heat capacity. See table 10.1 on p. 375
for examples.
 Water has an extremely high specific heat capacity
 Calculate specific heat capacity using the formula below.
Q= mcT
Q - amount of heat (J)
m -mass (g)
c -specific heat capacity (J/g C)
T - change in temperature (C)
T = T2 - T1
See model Problem on p.376
Do practice problems #1-9 on p. 377
Phase Change
 Energy is required to either melt or evaporate a substance.
 Conversely, energy is released when a substance is solidified or condensed
Copy fig. 10.14 into your notes
 Heat of fusion (Hfus): The amount of heat required to melt one mole of a
substance.
*Note: The heat released by one mole of a substance freezing is equal to the
amount of heat required to melt it.
 Heat of vaporization (Hvap): The amount of heat required to evaporate one
mole a substance.
*Note: The heat released by one mole of a substance freezing is equal to the
amount of heat required to evaporate it.
 The units for heat of fusion and heat of vaporization are J/mol
 Every substance has its own heat of fusion and vaporization. See table 10.2
on p.381.
To calculate Heat of Fusion and Heat of Vaporization use the following
formulas:
Heat of Fusion
Heat of Vaporization
Q= nHfus
Q= nHvap
Q -amount of heat (J)
n -number of moles
Hfus- heat of fusion (J/mol)
Hvap - heat of vaporization (J/mol)
See model problem p.382
Do practice problems 10-18 on p.383
Earth's Radiation Budget (p. 366-368)
 If the earth did not have an atmosphere, surface temperatures would be
too cold to sustain life. If too many gases that absorb and emit infrared
radiation were present in the atmosphere, surface temperatures would be
too hot to sustain life.
 When averaged over a year, the incoming energy in both the earth and its
atmosphere equals the outgoing energy. If we consider the entire Earthatmosphere system, then the amount of radiation entering the system
must equal to the amount leaving, or the system would continually heat or
cool.
 Note: Latent heat is energy used to melt snow and ice.
Sensible heat is heat energy that you can sense or feel.
Incoming Solar Radiation
 The sun emits electromagnetic radiation of various wavelengths that
travels through the vacuum of space, eventually reaching the earth.
 Most of the sun's radiation that reaches the earth is in the visible part
of the spectrum.
 The different wavelengths of solar radiation are affected differently as
they enter the Earth's atmosphere.
 Visible light reaches the Earth more or less unchanged. Some of it is
reflected by the Earth's surface and the rest is absorbed.
 The absorbed sunlight warms the surface, causing the Earth to emit
infrared radiation (heat).
 Of all the energy reaching the earths surface 49 - 51% is absorbed by
the Earth's surface
Outgoing Radiation
 The Earth's atmosphere cannot absorb light, but it can absorb infrared
radiation emitted by the earth.
 The atmosphere absorbs and temporarily traps some of the infrared
energy causing the air to be warmed. The warm air re-emits the radiant
energy in all directions. Some of the energy is emitted into space, but
some of it makes its way back to the Earth, further warming the
surface.
 It is this re-emission to the earth's surface that maintains a higher
temperature on our planet than what would be possible without an
atmosphere.
 Not all of the energy emitted by the Earth is radiative energy; some is
sensible (you can sense or feel the heat) and latent heat (used to melt
ice and snow).
 The color of a surface affects how much energy it will reflect or absorb.
Dark colors absorb more energy and light colors reflect more energy.
This phenomenon is called the albedo effect. For example, snow has a
very high albedo. It reflects 70 -80% of the energy striking it.
Greenhouse Gases and The Greenhouse Effect: (p.368)
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If Earth had no atmosphere, the globally averaged surface temperature
would be -19 degrees Celsius. Because Earth does have an atmosphere, the
average surface temperature actually is 15 degrees Celsius (33 degrees
warmer!).
The atmosphere acts as a greenhouse because of gases that selectively
absorb and then re-emit solar radiation back to Earth.
Gases that absorb IR radiation are termed collectively as greenhouse gases
and include water vapor, carbon dioxide, ozone, molecular oxygen, methane,
CFCs, HFCs, and nitrous oxide.
Condensed water is also an efficient absorber and emitter of IR radiation.
Thus, clouds act in a manner similar to greenhouse gases.
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Gases in the atmosphere trap heat radiated by the earth, warming the
Earth. Scientists believe that recent increases in the production of
greenhouse gases have resulted in unnatural global warming.
Climate and Seasons: (p.368-374)
 Climate: The trend in temperature, atmospheric pressure, humidity, and
precipitation over a period of many years.
 Weather: The conditions at one place at one time.
What Causes The Seasons?
 As the Earth obits the Sun it rotates on its axis
 The 24hr. rotation of the Earth on its axis results in warming during the day
and cooling at night.
 The Earth is tilted slightly on its axis. The tilt of the Earth is called its angle
of inclination. . (See fig 10.9 on p.373)
 If the earth were not tilted, the sun would constantly shine directly over the
equator. The amount of solar radiation received at different latitudes
would remain the same throughout the year and there would be no
seasons!
 The angle of inclination determines the relative length of day and night at
different latitudes. At the equator day and night are each 12 hrs. long every
day of the year.
 At the poles, the Earth is tilted towards the sun for half the year and away
from the sun for the other half of the year.
 While one hemisphere is tilted towards the sun experiencing summer, the
other hemisphere is experiencing winter.
 The Earth's orbit is not circular it is elliptical. Also, the sun is not at the
exact center of the Earth's orbit. The Earth moves faster when it is closest
to the sun, due to the Sun's gravitational pull, and slowest when it is
farthest from the sun. This results in unequal lengths of seasons.
Why are the poles cold all year round, even in the summer?
 Even though the North Pole is tilted toward the sun from June 21
to September 23, it remains cold.
 This is because the Earth experiences uneven heating.
 This uneven heating is due to the curvature of the Earth.
 IR from the sun strikes the equator directly, but the further you go
from the equator, the angle of incidence becomes progressively
sharper.
 The sharper the angle the Sun's rays strike the Earth, the less
energy is absorbed. (See fig 10.10 on p.374)
Now do Check Your Understanding on p. 374 #1-7
Causes of Natural Climate Change: (p.422)
 Scientists today still cannot fully explain natural changes to the
Earth's climate. However, several possible factors have been
identified that can help explain why the Earth's climate continues
to change.
1. Earth's Tilt
 The amount of solar radiation reaching any part of the Earth
depends on the tilt of the Earth.
 The Earth today is tilted 23.5 to the plane of its orbit
around the Sun. Over the history of the Earth, this tilt has
fluctuated between 22.3 and 24.5.
 When the Earth is at its maximum tilt the poles receives
more solar radiation resulting in a much warmer climate at
the poles. See figure 11.34 on p. 422.
2. Earth's Orbit
 The shape of the Earth's obit fluctuates over a period of
about 100 000 years. The shape of the Earth's orbit ranges
from a perfect circle to an oval.
 A more oval shaped obit distances the Earth from the Sun
during some seasons. These changes in the shape of the
Earth's obit have been correlated with periods of glaciation.
3. Continental Drift
 All landforms sit on top of tectonic plates floating on the
Earth's hot, molten core.
 225 million years ago all of the plates were joined together
as a supercontinent called Pangaea.
 200 million years ago the continents began to drift apart.
The continents continue to slowly drift even today.
 As continents drift from one latitude to another their
climates are changed.
 The slow movement of the continents also causes opening
and closing of ocean basins resulting in changes in thermal
energy transfer on land, wind, and precipitation.
4. Weathering
 Weathering is the process that breaks rocks down into
smaller pieces.
 Weathering can be either physical or chemical.
 During the chemical weathering process, carbonic acid is
formed by the reaction of atmospheric carbon dioxide with
water vapor in the atmosphere.
 This process removes the greenhouse gases carbon dioxide
and water vapor from the atmosphere.
5. Catastrophic Events:
 Large asteroids or meteor collisions and major volcanic
eruptions put enormous volumes of dust, ash, and smoke
into the atmosphere.
 A dark thick cloud of soot, dust, and smog forms around the
Earth. This cloud would then prevent sunlight from reaching
the Earth.
 Photosynthesis quickly slows down and temperatures drop.
 The sudden reduction of plant materials causes starvation in
many species. This results in the mass extinction of many
species (e.g. The dinosaurs).
 Some scientists also believe that the climate would then
experience a warming period due to an increase in carbon
dioxide and other greenhouse gases in the atmosphere.
 There is strong evidence that a large meteorite struck the
Earth 65 million years ago in New Zealand. This meteor
would have struck at about the time of the extinction of the
dinosaurs!
6. Feedback:
 Negative feedback: A change in one direction triggers a
change in the opposite direction.
 Positive feedback: A self-perpetuating situation
Copy figure 11.37 from p.424 in the space below.
Now do Check Your Understanding p. 428 #1-7
Now do Check your Understanding p.396 #1-6 and
Ch. 10 Review p. 399 #2,4,5,6,7,9,11,12,14,16,20,22,26,27-30 and
Ch. 11 Review p.430 #2,3,6,9,10,11,12,14,18,30