Transcript File - Achal Science

Unit 4
Energy Flow in Global Systems
1.0 Climate and the Biosphere
Enduring Understanding:
Climate results from interactions among the components of the
biosphere
•
•
Earth – Our Biosphere
Climate
1.1 Earth – Our Biosphere
•
•
•
•
•
Weather refers to the conditions of air pressure, temperature, cloud
cover, precipitation, and humidity that occur in a particular place at a
particular time
Climate is the average weather conditions that occur at a particular
place at a particular time
Climate results from interactions among the components of the
biosphere
Biosphere is a thin layer of earth that supports life
The components include:
• The Atmosphere
• The Lithosphere
• The Hydrosphere
The Atmosphere
•
•
•
•
•
Rises over 500km from the surface
of the Earth
Composed of a mixture of many
gases
Water vapor concentration will vary
greatly depending on factors such as
location and temperature
Suspended particulate matter in the
atmosphere is called atmospheric
dust, and includes pollen,
microorganisms, soot, exhaust
Nitrogen – 78%, Oxygen – 21%,
Trace Gases – 1%
Layers of the Earth’s
Atmosphere
•
•
•
•
•
Layers of the atmosphere are
determined by the altitude, or the
height above the surface of the
Earth
The Troposphere is the layer of
gases 0-10km above the surface
of the Earth
Temperature will decrease as the
altitude increases, reaching a
minimum of –60oC
Supports life
Contains the highest
concentration of atmospheric gas
by mass and atmospheric dust
•
•
•
•
•
•
•
•
The Stratosphere is the layer above the troposphere and
extends 10km – 50km above the surface of the Earth
The temperature of the stratosphere increases as altitude
increases, from –60oC to 0oC
Contains most of the ozone gas, and thus, the ozone layer exists
in the stratosphere
The Mesosphere is the third atmospheric layer above the
Earth’s surface
Temperature decreases with altitude, from 0oC to -100oC
The Thermosphere is the farthest layer from the Earth’s
surface
Temperature increases with altitude, from –100oC to 1500oC
There is little gas in these layers and temperature changes are
not fully understood
The Lithosphere
•
•
•
•
Includes the solid portion of the
Earth that floats on the layer of
semi-fluid in the upper mantle
Home to many plants, animals,
micro-organisms
Extends about 100km below the
surface of the Earth
Warmed by the sun and the
molten material in the mantle
The Hydrosphere
•
•
•
•
Accounts for all water on Earth
97% is salt water, 3% is fresh, including frozen water, such as
ice, snow and glaciers
The amount of water is relatively unchanging
Warmed by sunlight and the molten material found in the mantle
The Components of the Biosphere
Interact
•
•
To understand global systems, need to examine how the
components of the biosphere interact
Ex. Water does not just exist in the hydrosphere, it is important
in the Earth’s atmosphere in cloud formation and the cycling
through the hydrologic cycle
Altitude and Temperature
•
•
•
•
The temperature of the atmosphere is highly dependent on the
layer of atmosphere being measured
The temperature that affects life the greatest is in the
troposphere
Usually as altitude increases, temperatures will decrease
Inversion is the opposite; cold air is trapped close to the ground
(occurs close to mountains); pollution may also be trapped
1.2 Climate
•
•
•
•
Climate impacts life
Regions with severe climates will have limited human populations
(extreme heat or extreme cold)
Affects cost of living for the individuals
• Housing, heating, air conditioning, clothing, transportation,
food types, tourism, recreation activities
Affects other organisms too so they need special adaptations in
order to survive
• Plants: dormant stage, reproduction, water sources, etc
• Animals: hibernation, food sources, fat layers, etc
Climate Change
•
•
•
•
•
•
Climate change is change that occurs in the climate of a region over
time, usually a duration of 30 years or more
Scientists compare average weather conditions over a similar period of
time from the past
Earth has experienced substantial climate change in the past, according
to evidence such as ice core samples and fossil record
Anecdotal and scientific evidence is gathered to determine if Earth is
undergoing another climate change
Anecdotal evidence refers to reports from people on particular
weather patterns and how they believe the climate is changing over
time
Scientific evidence relies on evidence of climate change through data
collection over a period of time
Interpreting Climate Data
•
•
•
Even though scientists may
have data collected and
analyzed, it can be very difficult
to interpret
Have to be careful not to over
generalize the data
Since we do not have a
complete history of the Earth’s
climate change, it is difficult to
make hypotheses about the
change in Earth’s climate over
the past few decades
2.0 Global Systems
Enduring Understanding:
Global systems transfer energy through the biosphere
•
•
•
•
•
Energy Relationships and the Biosphere
Thermal Energy Transfer in the Atmosphere
Thermal Energy Transfer in the Hydrosphere
Earth’s Biomes
Analyzing Energy Flow in Global Systems
2.1 Energy Relationships and the
Biosphere
•
•
•
•
•
•
Virtually all energy comes from the sun on Earth, from Solar
Energy
Most of the solar energy is converted to thermal, or heat energy
Solar energy is radiant energy, energy transmitted as
electromagnetic waves
All areas on Earth do not receive the same amount of solar
radiation
Insolation is the amount of solar energy received by a region
on the Earth’s surface
Insolation depends on altitude, and specific characteristics of the
lithosphere, atmosphere and hydrosphere in a region
Insolation and the Angle of
Inclination
•
•
•
The poles of the Earth are slightly tilted
The angle of inclination refers to the degree by which Earth’s
poles are tilted from the perpendicular orbit of the Earth
Earth’s angle of inclination is 23.5o
Seasons of the Earth
•
•
•
Earth orbits the sun once a year
During the summer in the Northern hemisphere, the angle of
inclination causes the northern hemisphere to be slightly closer
to the sun, thus the average climate is warmer
On the First day of winter, however, the northern hemisphere is
tilted slightly away from the sun, and thus the average climate is
generally cooler
•
•
•
•
•
•
Earth can also be divided into different latitudes, which are
imaginary lines that run east to west on the surface of the Earth
The equator is 0o and the north and south pole are both 90o
The rest of the surface can be divided by parallel lines
The angle inclination will cause variations in the number of hours
of daylight at different latitudes
A solstice is one of two points in the Earth’s orbit when the
poles are most tilted towards or away from the sun, and
subsequently has the longest, or shortest days of the entire year
The equinox is when the number of hours of daylight matches
the number of hours of darkness; Earth has two
Insolation and the Angle of Incidence
•
•
•
•
The shape of the Earth also affects the insolation of regions of
different latitudes
Earth is spherical
As a result, most sunlight striking the Earth’s surface is not
perpendicular to the surface of the Earth, but strikes at an angle
The angle of incidence is the angle between the ray falling on
the Earth’s surface, and surface of the Earth
•
•
•
•
At the equator, the angle of incidence is 0o, at the poles, it will
be much greater
At larger angles of incidence, the same amount of radiation is
spread over a larger distance, thus the average temperature for
that region is cooler because there is less solar energy per
square km
With these two factors, angle of incidence and inclination, the
Earth’s climate will vary greatly from region to region
Regions closer to the equator experience little variations in
climate generally, and being farther away from the equator,
regions experience greater variations in climate
Absorption and Reflection by the
Biosphere
•
•
•
•
•
Solar radiation reaching the Earth is either going to be absorbed or
reflected back to the atmosphere
When particles reflect energy, they simply change the direction of
the solar ray
When particles absorb energy, they simply convert it to another
energy form
Absorbing energy will cause an increase in temperature of the
substance
Absorption and reflection occur in all three components of the
biosphere
•
•
•
Ex. Absorption of solar radiation in the hydrosphere drives the
hydrologic cycle
Ex. Absorption in the lithosphere warms the Earth and drives the
photosynthetic cycle
Ex. Various gases in the atmosphere absorb different
wavelengths of the radiation coming in and protect life from xrays and gamma rays
Cloud Cover and Atmospheric Dust
•
•
•
Most cloud cover and atmospheric dust occur in the troposphere
Clouds reflect some incoming solar radiation back into space, and
also absorb energy radiated back from the Earth, which helps
warm the Earth
Atmospheric dust behaves in the same way
Albedo
•
•
•
•
The amount of solar radiation absorbed or reflected from the
surface of the Earth can vary greatly depending on the
characteristics of the surface of the Earth
The albedo of the surface refers to the percent of radiation
reflected back to the environment
Light, shiny environments, such as snow, water or ice, reflect
more than dull, dark surfaces, thus they have a a higher albedo
The average albedo of the Earth’s surface is 0.3 or 30%,
however, each region has a different albedo value
Global Albedo of Earth’s Surface
Natural Greenhouse Effect
•
•
•
•
•
•
•
•
Some of the radiation that strikes the surface of the Earth is reemitted as infrared radiation (heat)
This helps heat the Earth and make it sustainable for life
Most of this infrared radiation is absorbed by clouds, water
vapor, and gases like methane and carbon dioxide
Without this absorption, the Earth would cool at quick rate,
making it uninhabitable for life
This process is known as the natural greenhouse effect
Greenhouse gases are those gases that absorb the heat and
thus, contribute to the greenhouse effect
The main greenhouse gas is water vapor
However, methane and carbon dioxide are also major absorbers
Net Radiation Budget
•
•
•
•
•
Not all incoming radiation is absorbed
Some is re-emitted as thermal energy
The net radiation budget is the difference between the
incoming radiation and the outgoing radiation
Incoming radiation is all of the radiation that reaches the surface
of the Earth
Outgoing radiation refers to that which is emitted from the
Earth’s surface and atmosphere
Net radiation budget =
Incoming radiation – outgoing radiation
Net Radiation and Latitude
•
•
•
•
•
On average the incoming radiation is equal to the outgoing
radiation, otherwise the Earth’s average temperature would
increase or decrease
Although this is true, some areas on Earth have varying net
radiation budgets
Polar regions will tend to always have lower insolation, and
higher albedo, as a result will have a lower amount of incoming
than outgoing
Thus, polar regions have net radiation budgets that tend to be
negative, or in deficit
Temperatures in these areas do not tend to decrease due to a
redistribution of thermal energy through convection current
patterns that exist on the Earth
2.2 Thermal Energy Transfer in the
Atmosphere
•
•
•
Thermal energy transfer is the movement of thermal energy
from areas with high temperatures to areas with low
temperatures
Radiation is the transfer of energy in a wave form
When waves or rays encounter matter, it is transferred through
conduction or convection
Conduction
•
•
Conduction is the transfer of energy through the direct collision
of particles, without moving the particles to a new location
Takes place in solids, where particles of higher kinetic energy
transfer energy to particles with lower kinetic energy
Convection
•
•
•
•
•
•
•
Convection is the transfer of thermal energy through the
movement of particles from one place to another
Occurs in fluids, such as liquids or gases
During convection, the particles form a current
When the particles in a fluid are heated, they expand, and take
on a lower density, thus they rise
Particles that are cooler sink and replace the recently moved
particles, because of their lower density
The new particles get heated, and rise because of an increase in
volume and a decrease in density
The cycle forms a current
Effects of Thermal Energy Transfer in
the Atmosphere
•
•
•
Because the temperature of
the atmosphere tends to
increase at the equator, gases
near the equator tend to rise
because they are less dense
In areas close to the poles,
where the gases are cool,
they tend to remain close to
the Earth’s surface
If the Earth did not spin, the
air would circulate in a
convection current from the
poles to the equator and back
again
The Coriolis Effect
•
•
•
Because the Earth spins, the
convection currents are
deflected either towards the
right or the left
The Coriolis effect is the
deflection of any object from
a straight line of path by the
rotation of the Earth
Thus, winds in the Northern
Hemisphere deflect right, and
in the Southern Hemisphere,
deflect left
Global Wind Patterns
•
•
•
•
The convection currents on the Earth
and the Coriolis effect result in global
wind patterns, transferring energy to
areas with deficit net radiation budgets
from ones which have a surplus
At latitudes of 30o N and S, some of the
air from the equator is sufficiently
cooled, and thus begins to sink before it
reaches the poles
The rest of the air is pushed up, and
continues to move east (because of the
coriolis effect), which causes cold air to
move in from a west direction, giving
rise to westerly winds
At the poles, cold air is pushed
eastward, thus forming easterly winds
Jet Streams
•
•
•
•
Local conditions, such as the presence of large bodies of water
will also affect wind patterns
Earth’s surface may slow global winds
A jet stream is fast moving air in the stratosphere, because
these winds are not slowed by the conditions of the Earth’s
surface
Jet streams, because of their location, speed and temperature
cause severe weather conditions such as squalls, storms, and
cyclones
2.3 Thermal Energy Transfer in the
Hydrosphere
•
Hydrosphere moves the thermal energy from the equator to the
poles with the help of global winds.
• Trade winds between equator and 30° N/30 ° S drive warm
waters
• Westerly winds between 30° and 60° N/S bring warm
waters to the poles
• Easterly winds between 60° and poles N/S bring cooler
waters towards equator
• Northern hemisphere currents flow clockwise and Southern
hemisphere currents flow counterclockwise
• Convection currents will also bring warmer water from ocean
floor to surface and cooler water from surface to the floor
Specific Heat Capacity (unit = c)
•
•
•
•
Is the amount of energy needed to raise the temperature of 1g
of a substance by 1° C.
c of water is 4.19 J/g °C; c of aluminum is 0.897 J/g °C
Water has a high c which means that it takes a lot of energy to
heat it up and a lot of energy is released when it cools
c of water is higher than that of air and so temperature changes
in areas close to large bodies of water are smaller than inland
locations
Quantity of Thermal Energy (unit = Q)
•
Is the amount of thermal energy absorbed/released when the
temperature of a specific mass of a substance changes by a
certain number of degrees.
• Q = mcΔt
• Where Q = quantity of thermal energy (J)
• m = mass of substance (g)
• c = specific heat capacity (°C)
• Δt = change in temperature (°C)
• Can use a calorimeter to determine the transfer of heat or c
Hydrologic Cycle and Energy Transfer
•
•
•
•
Thermal energy released/absorbed with each phase
change in the cycle
To break bonds, energy needed (solid  liquid 
vapour)
To form bonds, energy released (vapour  liquid 
solid)
Neither of these result in a temperature change; that
only occurs with an increase or decrease in kinetic
energy
•
•
•
•
•
•
•
Add temperature to ice
Temperature increases
Absorbed thermal energy converted to kinetic energy
Ice changes state, but temp remains constant because absorbed
energy not converted to kinetic energy, but used to break the
bonds between the water molecules
Water (liquid) continues to absorb thermal energy, temperature
increases
At boiling absorbed thermal energy breaks bonds between liquid
water molecules; temperature stays constant
Water (gas) continues to absorb thermal energy, temperature
increases
Heat of Fusion
•
Is the amount of energy absorbed when 1 mol of a substance
changes from solid to liquid without a change in temperature
•
•
•
•
•
•
•
Hfus = Q/n
Where Hfus = heat of fusion (kJ/mol)
Q = quantity of thermal energy (kJ)
n = amount of substance in mol (mol)
Hfus of ice = 6.01 kJ/mol
If mass of substance given, need to calculate n with
• n = m/M
• Where n = amount of substance
• m = mass (g)
• M = molar mass (g/mol)
Heat of solidification is the opposite; energy released when 1 mol
of solid forms from liquid
Heat of Vapourization
•
Is the amount of energy absorbed when 1 mol of a substance
changes from liquid to vapour without a temperature change
•
•
•
•
•
•
Hvap = Q/n
Where Hvap = heat of vapourization (kJ/mol)
Q = quantity of thermal energy (kJ)
n = amount of substance in mol (mol)
If mass of substance given, need to calculate n with
• n = m/M
• Where n = amount of substance
• m = mass (g)
• M = molar mass (g/mol)
Heat of condensation is the opposite; energy is released when 1
mol of vapour condenses to a liquid
2.4 Earth’s Biomes
•
•
•
Biome is a large geographical region that has a particular
range of temperature and precipitation levels; plants and
animals are adapted to each biome
It is an open system which means there is an exchange of
matter and energy with the surroundings.
The hydrosphere is a closed system because it exchanges
energy but not matter with the surroundings.
Earth’s Biomes
Tundra
•
•
•
•
•
•
•
Location: Arctic regions of North America and Eurasia (66oN)
Characteristics:
• Ground is permafrost
Hours of Daylight: Varies greatly over the year; 24 hrs – 0hrs
Insolation: Lowest of all biomes, thus highest albedo
Temperature: -15oC to 5oC
Precipitation: 20cm/y, mostly as snow
Growing Season: short, 20 – 30 days
•
Biotic Adaptations:
• Low biodiversity of plants and animals
• Plants have short lifecycles, are small and close to the ground
• Small animals tend to burrow under the ground
• Large animals fur covered and squat bodies to reduce loss of
thermal energy
Taiga
= Boreal Forest
•
•
•
•
•
•
•
Location: Broad belt around the
Earth, south of the tundra
Characteristics:
• Dominated by evergreen
conifer trees
• Cool summers, cold winters
Hours of Daylight: 16 hrs – 8hrs
Insolation: Slightly higher than
tundra
Temperature: 4oC - 14oC
Precipitation: 40 – 100cm/y,
mostly as snow
Growing Season: 4 – 5 months
•
Biotic Adaptations:
• More biodiversity than tundra
• Leaves of conifers tend to be needle-like and contain resin to
avoid freezing, yet still undergo photosynthesis
• Animals tend to be inactive during winter by hibernating or
burrowing
• Animal coats change colours with season
• Birds migrate out of Tiaga during winter seasons
Forest (deciduous)
•
•
•
•
•
•
•
Location: Parts of North and South America, Europe, Asia, Japan
and Australia
Characteristics:
• Dominated by deciduous trees
• Well defined winter and summer seasons
Hours of Daylight: 12 – 8hrs
Insolation: Varies based on Season
Temperature: 14oC - 24oC
Precipitation: 75 – 100cm/y
Growing Season: Longer than Taiga
•
Biotic Adaptations:
• Leaves tend to be broad, thus
more efficient at
photosynthesis
• Leaves freeze easily and tend
to lose water through
transpiration
• Leaves are lost before winter,
allow the tree to survive
• Animals remain active year
round, and reproductive
cycles depend on season
Grassland
= prairies/savannas
•
•
•
•
•
•
•
Location: Any region with at least 20cm/y precipitation
Characteristics:
• Grassy, with few to no trees due to lack of precipitation
• Savanna grasslands have a wet season and a dry season
• Prairie grasslands have winter and summer seasons
Hours of Daylight: 10 – 8hrs
Insolation: Relatively same throughout the year, dependent
on latitude
Temperature: 4oC to 30oC
Precipitation: 25 – 57cm/y
Growing Season: year round
•
Biotic Adaptations:
• Grasses are tall, shrubs are short, trees are scarce
• Grasses have extensive root systems to allow for quick
recovery from drought, cold or grazing
• Most plants die off each year and start with seed when
weather permits
• Drought – tolerant flowering plants
• Animals adapted to a drier climate
• Most animals tend to be grazers
Rainforest
•
Location: South America, close to equator,
parts of Africa
•
Characteristics:
Highest biodiversity of all biomes
• Short dry season
Hours of Daylight: 12 – 10 hrs
Insolation: Same throughout the year, at
the equator
Temperature: 25oC - 30oC
Precipitation: >200cm/y
Growing Season: year round
•
•
•
•
•
•
•
Biotic Adaptations:
• Dominant plants are broad leafed trees
• Other species of plants grow under or on the trees (ie. Vines)
Desert
•
Location:
•
Characteristics:
•
Hours of Daylight:
Insolation:
Temperature:
Precipitation:
Growing Season:
Biotic Adaptations:
•
•
•
•
•
2.5 Analyzing Energy Flow in Global
Systems
•
•
Climatograph use to help analyze or summarize the average
temperature and precipitation for each month in a year for a
location
It can be used to compare two areas, but the graphs need to
have the same y-axis scale
Factors that Affect Climate
•
•
•
Insolation – related to latitude, cloud cover,
albedo, atmospheric dust
Global winds
Warm/cold currents in oceans, c of water and air
3.0 The Change in Our Climate
Enduring Understanding:
Changes in global energy transfer could cause climate change, and
impact human life and the biosphere
•
•
•
Climate Change – Examining the Evidence
International Collaboration on Climate Change
Assessing the Impact of Climate Change
3.1 Climate Change – Examining the
Evidence
1.
Changes in greenhouse gases:
•
Four main types of gases: water
vapour, carbon dioxide, methane
and nitrous oxide
•
GWP (global warming potential)
measures gases and their
abilities to trap thermal energy
•
Greenhouse gases absorb heat,
and so an excess amount of it
would lead to a change in the
net radiation budget
2. Greenhouse gases and human activity
• Since the industrial revolution, greenhouse gases have increased, humans
more dependant on fossil fuels
• Fossil fuels have large amounts of carbon, release methane and carbon
dioxide during its’ production and carbon dioxide and nitrous oxide when
burned
• Carbon source is a process that releases carbon dioxide into the
atmosphere
• Carbon sink is a process that takes carbon dioxide out of the atmosphere
• Ideal to have a balance between the two
• Agriculture releases a large amount of gases through manure and chemical
fertilizers, methane, decaying garbage and plant life
• Halocarbons are man-made chemicals that can absorb thermal energy, also
is a coolant and a powerful greenhouse gas
•
•
Enhanced greenhouse effect is caused by an increase in human
generated greenhouse gases that result in a change in the net
radiation budget
Global warming is an observed increase to the average
temperature of Earth
• Humans continue to increase the carbon source and decrease
the carbon sink, so a balance is not present
• Evaluation of climate change evidence is limited because the
interactions between all of the systems are so complex
3.2 International Collaboration on
Climate Change
•
Scientific collaboration on climate change
• Confidence level increases because of:
• Scientists working together to pool their research and
knowledge
• Advance in technology like general circulation model
(GCM), satellites, high-altitude jets, and deep sea
submarines
•
Political Collaboration
• Montreal Protocol
• International agreement to phase out production and use
of CFC’s
• Signed in 1987 by 182 nations
• CFC’s invented in 1946, found to turn ozone into oxygen
which depleted the ozone layer
• Ozone helps absorb UV radiation so thinning of the layer
would result in more UV radiation hitting Earth’s surface
• HCFC (hydrochlorofluorocarbons) have been used instead
because they thin the ozone layer at a slower rate, still
trying to find an alternative to this too
• Canada hoping to ban the use of HCFC’s by 2020
•
United Nations Framework Convention on Climate Change
(UNFCCC)
• Nations acting to stabilize greenhouse gas emission
caused by human activity, cannot threaten global food
production or economic interests of nations
• Must support sustainable development (which is the use of
resources in methods and process that maintain them for
future generations)
•
Kyoto Protocol on Climate Change
• 161 countries set a goal to lower emissions by 5 % by
year 2012
• Emission-reduction credits are given to countries that help
decrease emission
• Developed nation can help developing nation decrease
emissions
• Developed nation can help another developed nation
that has a temporary economic issue
• Nation acts to remove carbon dioxide from the
atmosphere
• Nations sign the protocol and voters need to agree on it
•
Stabilizing greenhouse gas levels
• Decrease emissions, increase removal of carbon dioxide
• Carbon dioxide sequestering is when carbon dioxide is
pumped into the ground to extract oil reserves and then
sealed underground
3.3 Assessing the Impact of Climate
Change
•
Climate change can result in an increase in
temperature, severe weather patterns,
damage to property and crops, increase in
drought, melting of polar ice, flooding, etc
Impacts of Climate Change on
Alberta
•
Economies can be affected by drought,
increased numbers of insects, increased
forest fire risks, wildlife adaptations