Global Systems year 10
Science
Systems that effect the globe!!!
Our planet…….from the
water/hydrological cycle, carboncycle, nitrogen cycle and Ocean
currents………….climatic effects
and Global Warming
OUTCOMES FOR THE TOPIC-students should
know/be able to-
Explain the natural cycling of matter- carbon,
nitrogen and water cycle
Influences over Earths Climate- ocean currents
Sea, ICE, glaciers, fossils and sea level -> all
evidence of climate change
Effects climate change has on ecosystems and
biodiversity
Comparisons of cause and effect of
“Greenhouse effect”
Evidence that world climates have changed
and will continue to do so
The “MEASURABLE” Changes in the Earths
atmosphere in the 20th/21st century are related
to human activity
Starting with the Water CycleHYDROLOGICAL CYCLE as we call it now
we’re big people!!!!!!!!!!!!!!!
Pre Quiz……what do you remember?
1. Draw what you think the water cycle looks
like on a piece of paper ( students to do
this in work book- teacher note- handout
photocopy afterwards of the actual cycle to
compare/keep
1. Include words on your diagram like,
precipitation, condensation, evaporation
, underground water, runoff…………..YOU HAVE 3 MINS…GO
2. What things do you already
know/remember that influence
climate? Click for answer
Changes in ocean
temperature
Change in concentration of
gases in atmosphere
3.What is the carbon cycle?- you
should remember that carbon is
an element found in all living
things…..CLICK
“carbon Cycle” describes the ways
carbon changes form as it moves
through the environment and
atmosphere…
NO NEED TO NOTE…WE LOOK IN
DETAIL AT THIS CYCLE
4. What can you tell me about
Global warming… click after some suggestions
made
 Holes in ozone layer.. We have the “green house
effect”
 This is a bit like a blanket being put on the earth
trapping the warm air beneath….more heat in our
immediate atmosphere- overall warmer global
temperatures
 There is some evidence that global warming would
have occurred…..as climates have changed through
out the earth over time…..But has man hastened
it???
5. Tell me some of the Human
influences you know effect the
environment click …
POLLUTION
HABITAT DESTRUCTION
ETC
Vocabulary for this unit of work:
please
write as a list in your book and complete as we go
over these words throughout the topic.
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Atmosphere
Biosphere
Carbon cycle
Denitrifying bacteria
Fossil fuels
Hydrosphere
Leguminous plants
Lithosphere
Nitrogen cycle
Nitrogen fixing bacteria
Sustainable ecosystems
The hydrological Cycle…
Watch first part of Wild
Weather
DVD….. Click on “wet”. he explains the
water cycle/weather…….stop at the end
of his talk in his canoe as he goes under
water.
Then note the following important
points:
• Water is our most precious resource
• The same water that was here in the
beginning is still here today.
• Constant recycling of water occurs from evaporation
to condensation to precipitation…etc refer back to
your water cycle diagrams
• Evaporation occurs from the oceans, soil, plants and
even animals
• Largest amount of water vapour is from the ocean
as it is the largest body of water
• Are clouds vapour or liquid?????????? They are
actually liquid . This important to note
• Condensation is actually the opposite of evaporation
• In Evaporation heat is needed to change the liquid
water to vapour
• In Condensation and cloud formation the vapour is
attracted to dust particles in the air and then forms
a less random structure than in vapour and the
clouds are actually a liquid form of water we can
see. They release heat as they form. They float as
they are less dense than the air below them.
Precipitation is really just the liquid in the clouds
falling.
Just a little about density………we said clouds
float as they are less dense that air below
them…..they can weigh tons….but their mass is
spread over a large area and they are still less
dense than the lower air.
Density refers to the number of particles per unit
volume
LESS DENSE
MORE DENSE
DENSITY CONT:
In the atmosphere as the air is
heated……from the heat radiating from the
earths surface…the particles will move
farther apart and it becomes less dense
and rises….. It then cools the higher it
gets the particles move closer and it
sinks…..the clouds are still less dense than
the air and float on the slightly warmer
more dense air
Natural Influences on Climate
(pg 183 Pearsons)
Terms to Note:
WEATHER- state of the atmosphere in
relation to temperature, wind, cloud cover
and precipitation
Weather is created by interactions between
the hydrosphere (all water on earth) and
the Lithosphere( land masses) and the
atmosphere (the layers of gas around the
earth)
WEATHER- changes day to day
CLIMATE
CLIMATE: The long term
averages of weather
conditions
30 years of weather records
including extreme events are
used to describe the climate of
a particular place on our
globe.
Influences on climate include:
• Sun is the ultimate source of energykeeps the planet warm enough to
sustain life
• Energy form sun is a major influence on
climate
• Earths Surface-it’s the features on the
surface which determine the energy
reflected back into space
• Clouds and ice in the Artic and Antarctic
reflect most of the energy (84 %)
• Dark green forests in comparison -14%
Gases in the Atmosphere:
• Energy from sun- short wave radiation
• Absorbed by clouds and earths surface- radiated back to
space as long wave
• EARTHS ATMOSPHERE- oxygen and nitrogen –have no
effect on radiation coming in from sun or going out
• However, other gases in the atmosphere though less have
a greater effect on this radiation
• Water vapour, carbon dioxide, methane, and nitrous oxide
and ozone all allow short wave radiation through……but
absorb the outgoing long wave radiation
• They re-emit the heat in all directions….some being
radiated back to earth
• Its these gases that trap heat at the surface of the earth“ the green house effect” keeps the earth warmer
• This re-radiated heat is long wave and can’t pass through
glass hence the term “glass house or green house”…these
work on that very principal- heat in (passes through the
glass) trapped- keeps the greenhouse hotter great for
plants and some vegies etc…..cant escape so constantly
warmer than surrounding outside air.
Orientation of the Earth
• Earth basically spherical
• Orbits the sun and rotates on its axis
• The tilt and rotation causes the
seasons ( give diagram or look at pg
185 Pearsons)
• The rotation of Earth takes the
atmosphere and waters with it
• This movement influences our
circulation and water-globally
• However water circulation mainly
influenced by temperature
• Different temperatures of oceans
around the world impact Australia’s
climate now watch next bit Wild weather- currents
and clouds….stop when gets to hurricanes etc
Ocean Currents: spinning currents pg 185
• Continuous movements of ocean waters
• Flow for great distances and cause
water to circulate continuously around
the earth
• The circulation determines the climates
• Currents occur at the surface and deep
within the ocean
• Causes of currents:
• Wind
• Temp
• Variations in salinity
• Rotation of earth on its axis
• gravitational pull of sun and moon
MAJOR SURFACE CURRENTS
• Surface currents caused by wind
• Pushes surface water along until it
reaches land
• Water then flows left/right or down
• Major ocean basins-circular currents
form-gyres
• Flow clockwise in northern hemisphere
and anticlockwise in southern hemisphere
• Gyres patterns of circulation is caused by
rotation of the earth (diag next slide)
Deep Currents:
• Begin at the poles- its very cold water here!
• These deep currents flow through the ocean
carrying the very cold water along the bottom
• Surface and deep currents interact
• Water cycles from deep currents to surface
currents and back to the deep again- forms the
THERMOHALINE CIRCULATION (conveyor)
• Thermo-heat/temp, haline-salt, conveyertransportation
• Very slow-1600 years to complete a full cycle
• Distributes heat around the globe affecting
climates
Watch the animation link:- http://www.youtube.com/watch?v=3niR_Kv4SM
The Gulf Stream:
• Part of the global conveyor belt
• The current which makes western Europe warmer in
winter than anywhere else on the same latitude
• I.E UK and Norway warmer than Green land and
Canada
• FLOWS FROM THE CARRIBEAN SEA TO THE NORTH
ATLANTIC OCEAN
• Feeds into the north Atlantic drift, Norwegian
currents, into the Labrador and Greenland seas.
• Artic winds then cool the water-increasing the
density of the gulf stream
• Denser water- sinks pushes away water below
creates a deep current
• This deep cold current flows all the way south to
Antarctica
Australia's Climate:
• Australia –a land of contrast drought and floods can be
experienced at the same time
• These extremes the result of two phenomenon
• Southern oscillation
• Indian Ocean Dipole
SOUTHERN OSCILLATION
• sequence of changes that occur to the way the
atmosphere and water circulate across the Pacific
Ocean and Indonesian islands
• Most years a cold current flows north to south
America then west to equator- warmed by the
sun= temp difference of 3-8 degrees Celsius
between the cooler and the warmer western Pacific
• Page 187 Pearson's.
• Southern Oscillation index-measure of the
atmospheric and ocean conditions across the Pacific
Ocean-difference in air pressure between Tahiti and
Darwin
Continued…
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Normally this index is 0
During El Nino- very negative
During La Nina- strongly positive
EL NINO
• best known extreme southern oscillation
and most important influence on
Australia’s Climate-particularly in QLD and
NSW- little temp change , little air
pressure change, trade winds weaken,
cool air descends, little rainfall in this
period
Opposite occurs with La Nina-cooler, wetter,
more wind- this event can last for over a
year
http://esminfo.prenhall.com/science/geoani
mations/animations/26_NinoNina.html
Indian Ocean Dipole:
• Southern Australia influenced by the Dipolechange in temp of water between eastern and
western areas of the Indian Ocean, near the
equator
• Not a regular change- does not happen every
year or at the same time of year
• Starts in MAY OR June-peaks in AugustDecember
• Droughts are determined in Australia by the
amount by which the temp of the sea differs
and how long it lasts
• http://www.youtube.com/watch?v=CTMuqSghR
r8
Changing Climate:
• Evidence is there to support the thought that Australia’s
climate has been different in the past from what we
experience today
• Australia used to be joined to Gondwana- warmer and
wetter climate
• There has been cycles of warming and cooling
• Tasmania/and southern covered with ice 2.5 million
years ago (Glaciation)
• 20, 000 ago current period of warming began
• Ice Ages: ice caps expand at both poles –liquid
water on earth decreases
• Sea levels fall additional land exposed at the
coasts
Global Warming
• Interglacials are periods between glaciationsGlobal Warming
• Warming- means an increase in average world
temperatures
• Icecaps melt, sea levels rise, coastal lands
flood
• Evidence of rise and fall is seen in patterns
of sediments and fossils in coastal rocks
• Reasons for past global warming not really
understood
• Challenging to understand what
contribution Humans are making to present
period of global warming
Evidence for Climate change…
Glaciers:-advance when climates are cool/retreat when warm
as glaciers grow they grind against rocks on the sides and
floors of the valleys through which they flow- dragging rocks
along with them
This creates deep grooves or “scores” on the sides and when
the glacier retreats they are clearly visible
Leaves a pile of rocks- moraines
Ice Cores
• Sometimes snow falls on glaciers to form
annual recognisable layers
• Scientists take cores for places like
Antarctica-analyse the physical and chemical
properties of the ice –gaining information
about temp & composition of the air from
hundreds of thousands of years past- can
show variations in sea level and amounts of
C02 in the atmosphere over time frames
2010
• It was discovered that ice cores from
the Antarctic showed a strong link
between the amount of snow that falls
in Eastern Antarctica and droughts in
south western Australia
• Eastern Antarctica over the last 30
years has had higher snow falls- while
winter rains in SW Western Australia,
has dropped by 15%
• Reduce rainfall- climate changemodifying the path of the Antarctic
circumpolar Current
• Warm air to Antarctica-snowfall
• Cool dry air Australia- reduced
rainfall
POLLEN ANALYSIS
• Decays slowly
• Often fossilized
• Indicates the species growing when
sediments were laid down
• Changes in pollen types found-indicate
changes in vegetation and climate
SEA LEVEL CHANGE
• World wide distribution of sedimentary
rock and types of fossils are indicators of
change in sea level
• i.e sedimentary rock in central
Australia has fossilised sea creatures
Fossilized shells
Do some review quest pg 191 Pearsons
Back to the Carbon Cycle and
Nitrogen Cycle
• As said Carbon is essential for life
• Found in all living things, their dead bodies and
wastes
• Found in the atmosphere as carbon dioxide
• Used in photosynthesis
• There IS NOT AN ENDLESS SUPPLY
• Fossils are the preserved remains of once living
organisms
• Fossils fuels are made form the carbon of plants and
animals that died millions of years ago- coal and oil
• When burnt they release the coal and oil back into
the atmosphere…so does burning wood , but this
carbon has only been stored for hundreds to
thousands of years
• Earth’s largest store of carbon is in limestoneCalcium carbonate
The Carbon Cycle-
pg 178 Pearsons
Nitrogen Cycle
• Important cycle in Nature
• Nitrogen is released into the soil as ammonia
when an organism dies via bacteria
• 2nd group- of bacteria get energy from
ammonia and release nitrates back to soil
• Plants take both nitrates and ammonia up
through their roots
• 3RD GROUP- nitrogen fixing bacteria absorb
nitrogen trapped in soil in air pockets-convert
to ammonia and nitrates
• 4th group- Denitrifying bacteria-opposite to
nitrogen fixing –get their energy form the
nitrates and convert back to gaseous nitrogenreleased back into atmosphere.
Nitrogen cycle- pg 179 Pearsons