Download Earth`s Oceans

Earth’s Oceans
Freshwater
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vs.
3% of Earth’s water
 2% in glaciers
 1% lakes, rivers, &
aquifers
Mixture of substances
not just pure H2O
 Minerals from rocks
and pollutants from
air get mixed in
Density = 1.0g/cm3
Freezes at 0ºC
Seawater (differences)
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97% of Earth’s water
Mixture of substances
 96.5% water and 3.5%
dissolved salts
 NaCl is most abundant salt
 Dissolved gases include O, N,
CO2
Salinity varies from place to place
Density = 1.02-1.03 g/cm3
Freezes at -2ºC
Both Fresh and Seawater
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Respond to solar radiation (sunlight)
 Remember, the sun drives the water cycle
Visible Light
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Visible light is both absorbed and reflected
 Most wavelengths are absorbed
 Blue light is reflected
All wavelengths are absorbed by 100m depth so deep
lakes and oceans are dark except for surface
Absorption of Light
– Water absorbs light, which
gives rise to another physical
property of oceans—they are
dark
– In general, light penetrates
only the upper 100 m of
seawater
– Light sufficient for
photosynthesis exists only in
the top 100 m of the ocean
Infrared Rays
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Determine water temperature
Rapidly moving water does not have time to absorb infrared
rays
Lakes and ponds become warm because they absorb infrared
rays
Upper zone of ocean absorbs infrared rays so only surface is
heated
Surface temperature varies with latitude
Deep seawater is very cold (Don’t draw diagram until the end)
How Did the Oceans Form?
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About 4.5 billion years ago, there were no oceans
Sometime before 4 billion years ago, water vapor
in the atmosphere condensed and fell as rain
The rain filled the deeper levels of Earth’s surface
and the first oceans began to form
The Global Ocean
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All waterways on earth are
connected to the oceans
because almost all watersheds
empty into the ocean
Minerals & gases are carried
along with the water and
dissolve into seawater
The Global Ocean
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Oceans produce most of the
earth’s rain and oxygen (over
50%)
The ocean affects
every person on Earth
Divisions of the Global Ocean
≈ Pacific Ocean - largest
(North and
South)
≈ Atlantic Ocean - half the volume
of Pacific (North and South)
≈Indian Ocean - 3rd largest
≈Southern Ocean - newest
recognized in 2000
≈Arctic Ocean - smallest with most
covered in ice
Divisions of Ocean
All five of Earth’s oceans are connected to
each other by the ocean currents creating 1
global ocean
Ocean water contains salt
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Ocean water is 96.5% water
 Plus, ions of dissolved salts
Evaporation removes pure
water
 Leaving salt behind
Low levels of nutrients
(nitrogen and phosphorus)
Oxygen is added by plants,
bacteria, and atmospheric
diffusion
Ocean water is vertically structured
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Temperature declines with depth
Heavier (colder, saltier) water sinks
 Light (warmer, less salty) water stays near the
surface
Temperatures are more stable than land temperatures
 Water has high heat capacity (heat required to
increase temperature by a given amount)
 It takes more energy to warm water than air
Oceans regulate Earth’s climate
 They absorb and release heat
 The ocean’s surface circulation moves heat around
What’s in Ocean Water?
Oceans contain many dissolved solids and gases
 Dissolved solids like minerals and salts are
eroded from the land as rivers travel to the sea
 When the water evaporates, these minerals are
left behind; This is why the ocean is salty
 Some gases become dissolved in the ocean
through wave action; Others come from
photosynthesis and respiration of ocean
organisms
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Characteristics of Ocean Water
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Dissolved solids: Sodium chloride, or table salt, is the
most abundant dissolved solid in the ocean. Other
solids are also found in ocean water. (Draw next slide)
Salinity
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Amount of dissolved salts present in a sample of ocean
water
Described in parts per thousand
 ‰ is the notation for parts per thousand
Changes in Salinity - Climate and water movement affect
salinity; Coastal water, in cool, humid places, has low
salinity; Slow-moving bodies of water have higher salinity
than other parts of the ocean do
Salinity in various regions all differ
 Range from 33‰ to 40‰
 Average Salinity is 35‰
Salinity-generally increases with depth (WRITE THIS IN!)
Characteristics of Ocean Water
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Dissolved Gases Nitrogen, oxygen, and carbon
dioxide are the main gases dissolved in ocean water
More than half of Earth’s oxygen comes from the
surface layers of the ocean
About 93% of the world’s carbon dioxide is dissolved
in the ocean
CO2
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Has more than 60 times that is the atmosphere
Called carbon sink (can trap CO2 for thousands of
years); *copy the next graph
Behavior of Gases in Water
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You know that warm water dissolves solids more
easily than cold water
Try to dissolve sugar in cold and warm water, and
you’ll see that it’s true
Gases behave in the opposite way; Cold water
dissolves gases more easily than warm water
Open a warm and a cold soda; The warm one will fizz
more and go flat more quickly
This is because the CO2 dissolved in the soda stays
dissolved easier in cold water
Behavior of Gases in Water
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Pressure also plays a role in how
easily gases dissolve in water
If the water is under high
pressure, gases dissolve more
easily than water under no
pressure
To keep CO2 dissolved in soda, it
is bottled under pressure; When
you open the soda, it loses
pressure; The CO2 fizzes out and
the soda eventually goes flat
Temperature Zones (Draw in box!)
25°C
23°C
Surface
Surface Zone
0m
300m
5°C
Thermocline
700m
1°C
Deep Zone
to1200m
Temperature Zones
≈Sunlight heats the top 100m of
the surface zone
≈Surface currents mix the heated
water with cooler water in
surface zone
Surface Temperature Changes
Two factors affect surface
temperatures:
≈Latitude-water along equator is
warmer because it receives more
direct sunlight (So temp would be
lowest at the poles.)
≈Time of year more direct sun during
summer, so surface zone is heated
more
FYI - A Global Thermostat
≈Ocean absorbs and holds energy
from sunlight
≈Releases energy more slowly
than land does; This keeps our
temps from going to extremes
every day/night
≈Ocean currents move warm
water around our planet
Ocean Currents
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Oceans don’t just sit
still
Currents move ocean
water from place to
place, moving
nutrients and
organisms with it
One very important
kind of ocean current
is upwelling
Upwelling
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Defined as the movement of
deep, cold, nutrient rich
water to the surface
Because many nutrients sink
to the bottom of the ocean,
upwelling brings nutrients up
where surface organisms can
use them
These nutrient rich waters
near the surface create
productive fisheries
Upwelling
Wind blows away from
the shore, taking
surface water with it
 Deep water “wells up”
to replace the surface
water
 This brings deep, cold,
nutrient rich water up to
the surface
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Draw & label this diagram under the
Infrared Ray section! Remember to
draw the wavelength in the diagram!
Video Clips (15 min)
Exploring Oceans - https://www.youtube.com/watch?v=3GRA7ilM708
Birth of an Ocean - https://www.youtube.com/watch?v=PoV4qSwg7nc
5 Oceans of the Earth - https://www.youtube.com/watch?v=vy6dj_ZWOos
Why is the Sea Salty? - https://www.youtube.com/watch?v=EIDSMzXXzLM
Upwelling – http://www.youtube.com/watch?v=APMzM-xYlOs
Observe how upwelling occurs http://www.classzone.com/books/earth_science/terc/content/visualizations/es2405/es2
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