Download What are Density Currents?

Oceans
Topic: Seafloor Topography
Objectives:
• I will know seafloor features of the
continental margin
• I will know seafloor features of the deep
ocean basin
Water Planet
• ¾ (75%) of the Earth’s
surface is covered in
water
• No other planet in our
solar system is covered
by so much water
• Earth is truly a water
planet
Oceans and You
• Why Study the Oceans?
• The Oceans supply us with
food
• The Oceans create our
weather and greatly influence
global climates
• 44% of the world’s
population live near the
ocean
• 50% of the worlds oxygen
comes from the Ocean
• Finally, many resources,
such as food and energy
come from the ocean
Oceanography
• People who study the ocean
are called Oceanographers
• Oceanography is the study
of the physical, chemical,
and biological aspects of
the ocean
• These include seafloor
features, such as trenches;
or life-forms that dominate
the ocean
Ocean Exploration
• More is known about the surface of the moon than
the surface of the deep ocean
• Oceanographers first started mapping the ocean
bottom in the 1950’s
• Why?!
• We needed to provide maps of the ocean bottom
so our submarines could spy on other countries
• It was thought that the ocean floor was flat
• After mapping it, it was revealed that the ocean
bottom was far more complex than previously
thought
Sonar
• So how did we map
the ocean bottom?
• In the 1950’s, a new
technology called
sonar was developed
• Sonar uses sound
waves that bounce
off the bottom of the
ocean
Sonar
• Sonar is a system
that uses sound
acoustic signals and
reflected echoes used
to map the ocean
bottom
• Scientists measure
the time it takes for
the sound waves to
strike the bottom and
bounce back
Here is how it works:
What is Sonar?
• A system that uses sound acoustic signals
and _______echoes used to map the ocean
bottom
Answer Bank
Subduction
submerged
Deep
eroded
flat
Reflected
Steep
volcanic
Features of the Ocean Floor
• The ocean floor is divided into 2 major areas:
– Continental Margins (submerged edge of continents)
– Deep Ocean Basins (deeper parts of the ocean that lie
over oceanic crust)
Continental Margin
Deep Ocean Basins
Continental Margins
• The continental Margin is made up of the submerged edge of
continents
• It composed of the continental shelf and continental slope
• The continental shelf
Margin
is the flat Continental
zone of
shallow water near the
edge of a continent
• The continental
slope is the edge of a
continent that drops
off into deep water
Continental
Shelf
Continental
Slope
What are features of the Continental Margin?
Continental _____zone of
Shelf:
shallow water near
the edge of a
continent
Continental The _____edge of a
Slope:
continent that drops
off into deep water
Please Draw
and label:
Answer Bank
Subduction
submerged
Deep
eroded
flat
Reflected
Steep
volcanic
Deep Ocean Basins
• Deep ocean basins also have distinct features
• These features include broad, abyssal plains, submerged volcanoes
called seamounts, mountain ranges; and deep sea trenches
Mid-Ocean Ridge –
Abyssal Plains –
Underwater volcanic
extensive flat areas
Guyot - flat wave
mountain chain where Deep
Oceanislands
Basin
of the deep ocean
eroded
2 plates pull away
from each other
Seamounts – submerged
volcanic mountains
Trench - Long steep
depression that forms
as a result of tectonic
plate subduction
Where is the Trench???
• Here is a picture of the ocean floor near
Alaska, compliments of Google earth
• Outlined in red is a trench where two plates
collide and one subducts
Where is the
Trench???
• Outlined in red is
a trench where
two plates collide
and one subducts
Mid-Ocean
Ridge
Seamounts
D
E
G
A
F
E
D
B
C
Where is the mid-ocean ridge?
Where is a trench?
Where is the abyssal plain?
Where is a Seamount?
Where is the continental shelf??
Where is the continental slope???
What are features of the Deep Ocean Basins?
Long steep depression that
forms as a result of tectonic
plate_______
Abyssal Plains: Extensive flat areas of the
_____ ocean. Cover 50%
Underwater ______mountain
Mid-Ocean
chain where 2 plates pull away
Ridges:
from each other
_______ volcanic mountains
Seamount:
Trenches:
Guyot:
Flat, wave-______ seamount
Answer Bank
Subduction
submerged
Deep
eroded
flat
Reflected
Steep
volcanic
Summarize:
1. The continental _____ is the zone of shallow water
near the edge of a continent and the continental ____ is
the steep edge of a continent that drops off into deep
water
2. Mid____ ___are Underwater volcanic mountain chains
where 2 plates pull away from each other
3. ____ ____are Extensive flat areas of the deep ocean.
4. _____ are submerged volcanic mountains
Please draw the diagram below and label the following features:
Continental shelf and slope, Seamount, Mid-ocean
ridge, Abyssal Plains
Please draw and label the features:
Answer Bank
Seamount
Shelf
Abyssal plains
Ocean ridges
slope
Topic: Ocean Currents
Objectives:
I will know factors which influence water
density
I will know the difference between surface
currents and deep ocean density currents
I will know how the surface currents and
density currents connect up forming the
ocean conveyor
Ocean Water Density
•
•
•
•
•
•
•
What do you think effects ocean water density?
How cold the water is?
Perhaps, how salty the water is?
Actually, the answer is both!
Water becomes more denser (heavier) as it becomes colder
Water also becomes more dense (heavier) with increasing salinity
This is why people can float in the great Salt Lake in Utah
Ocean Water Density
• If we were to boil salty
water, only the water
molecules would evaporate,
leaving behind the salt,
creating a saltier mixture
• As a result the salty water is
more dense!
• Do you remember where on
earth salinity was greatest,
or where water was the most
dense?
What factors effect Ocean water density?
• _____ and _____ effect water density
• The colder and saltier the water is, the more
dense it is
Answer Bank
Equator
Poles
Wind
Desnity(2)
Temperature(2)
salinity
Ocean Currents: 2 Types
• There are 2 types of
currents:
-There are deep water
density currents
driven by
differences in
density
-And there are
surface currents
driven by wind
What are the 2 types of currents?
• Surface currents
powered by ___ and
density currents
powered by ______
and _____ Answer Bank
differences Equator
Poles
Wind
Density
Temperature(2)
salinity
Surface Ocean Currents
Ocean
surface
currents
If
you
recall,
the
earth
Is
If you
Ocean
further
currents
recall,
move
heat
heat
travels
are
very
important
for
distributing
heated
unequally
from
the
sun:
from
From
the
hotequator
to cold
to
areas,
thewould
Heat,
without
them
the earth
Direct solar radiation at the equator
AsAnd
a result
poles
byradiation
convection
currents
Be asurface
much
colder
place
indirect
solar
at the develop
poles
Surface Ocean Currents
• Surface currents move
water horizontally, or
parallel to the earths
surface
• They deliver warm water
to the poles by convection
• They spin clockwise in
the northern Hemisphere
and counter clockwise in
the southern hemisphere
Simplified Ocean Current
Surface Ocean Currents
• Ocean currents
form as a result Westerlies
ofThe
2 things:
Coriolis Effect and
– Global
wind
The continents
cause
Tradewinds
patterns
The currents to curve
Coriolis
to– the
right effect
in the northern
hemisphere, and to
the left in theTradewinds
southern hemisphere
Westerlies
Simplified Ocean Current
What are surface currents?
• Current that flows like a river in the top 100
meters of the ocean due to _____ winds and the
____effect
• They distribute heat from the ____ to the ____
spinning clockwise in the northern hemisphere
and counter clockwise in the southern
Answer Bank
Equator
hemisphere
Poles
Wind
coriolis
Density(2)
Temperature(2)
Salinity
global
Surface Ocean Currents
• There are
generally 2 types
of surface
currents: warm
and cold
• Warm currents
come from the
warm tropics or
equator
• Cold currents come
from the cold polar
zones
Simplified Ocean Current
Surface Currents
• In reality, ocean
currents are not that
simplified
• However, the general
movement is still the
same -- clockwise in the
northern hemisphere,
counter-clockwise in
the southern
hemisphere
Simplified Ocean Current
How are the currents spinning in the Northern Hemisphere?
How are the currents spinning in the Southern Hemisphere?
Clockwise in the
Northern Hemisphere
Counter-Clockwise in the
Southern Hemisphere
Where are the warm currents coming from?
Where are the cold currents coming from?
What current is of the West coast ?
What current is of the East coast ?
Warm Gulf
Stream current
Cold California
Current
Gulf Stream
• For as many years as ships
have sailed, sailors have
used surface currents and
global wind patterns to help
them travel quickly
• During the American
colonial era, ships floated
on the 100km wide Gulf
Stream current to go from
North America to England
Gulf Stream
• The Gulf Stream is a warm
water current that delivers
warm water from the equator
up along the east coast of
North America
• This current keeps the
climates of Iceland and Great
Britain mild or moderate
• Remember, warm ocean
currents create warmer than
normal climates
What are the 2 types of surface currents?
• Warm currents
from the _____
Example: Gulf
Stream current
• Cold currents from
the____
• Ex: California
Current
Answer Bank
Equator
Poles(2)
Wind
warm
Desnity(2)
Temperature(2)
Salinity
equator
Density Currents
Iceberg
Tropical Regions
Polar Regions
Therefore,
cold salty
water
This
density
flows
backout
to the 60o
0o
Warm
watercurrent
from
the
When
seawater
freezes,
it equator
locks
sinks
at
the toward
polar
regions
As
it the
moves
the
Equator
along
the
ocean
bottom
the salt
and
water
becomes
saltier
moves
toward
the
Poles
Bringing
oxygen
and
nutrients
with it
poles,
it begins
to cool
And
the
density
current
is complete
What are Density Currents?
• Deep water currents
that form due to
_____ and salinity
differences
Answer Bank
Equator
Poles(2)
Wind
warm
Desnity(2)
Temperature(2)
Salinity
equator
Thermohaline Conveyor
• The thermohaline
conveyor is a
global circulation
of ocean water
that combines
warm surface
currents and cold
deep water density
currents
Deep Water Density Currents
• This deep water
density current is
called the
Thermohaline
Conveyor
• Remember
“thermo” means
temperature or heat
and “haline”
means salt---the 2
things regulate
ocean water density
Thermohaline Conveyor
• Colors in blue
indicate saltier,
colder, density
currents
• Colors in Red
indicate
warmer,
surface
currents
What is the Thermohaline Conveyor?
• A global ocean current that combines
warm_____ currents and cold_____ currents
Answer Bank
Equator
Poles
Wind
Density(2)
Temperature(2)
Salinity
surface
Summary:
1)
2)
3)
4)
5)
Surface currents are powered by global
____and ______ affect
Surface currents spin ______in the northern
hemisphere and _____clockwise in the
southern hemisphere
Warm currents come from the ___ and cold
currents come from the ____
Density currents develop from _____and _____
differences
The thermohaline ______is a global ocean
current that combines surface currents and
density currents
Answer Bank
equator
Coriolis
Winds
Poles
Temperature
Conveyor
Salinity
counter
Topic: Ocean Environments
Objectives:
• I will know the difference between the
benthic and pelagic zone
• I will know the importance of
phytoplankton and their role in the ocean
• I will know the process of upwelling and
it’s importance along California's coast
Ocean Environments
• The ocean can
be divided into
2 parts
• The Benthic
zone and the
Pelagic zone
Ocean Environments
• The benthic
zone makes
up the bottom
of the ocean
• Animals that
live on the
bottom live
on the benthic
zone
Benthic Communities
Ocean Environments
• The pelagic
zone makes
up the open
ocean
• Animals that
live in the
open ocean
live in the
pelagic zone
Pelagic
Organisms
Giant Squid
Creatures of the abyss – Angler Fish
Hag
Fish
Creatures of the abyss –
viper fish and an angler fish
What are the 2 major ocean environments?
• Benthic zone-region that goes along
the______
• Pelagic zone- _____ ocean region
Answer Bank
Nutrient
50%
Open
Bottom
base
Ocean Ecology
•
•
•
•
The ocean produces 50% of the earth’s oxygen
But what produces that oxygen?
Phytoplankton!
Phytoplankton, are microscopic plants that produce oxygen through
photosynthesis
• Phytoplankton live near the ocean’s surface where sunlight is
present
Ocean Ecology
• If you remember, Sunlight, Carbon Dioxide, and
Water are needed for photosynthesis
• Oxygen is given off! So go on, take a deep
Breath!
Phytoplankton
take in Sunlight,
Carbon Dioxide,
and Water
for Photosynthesis
Oxygen is
given off!
Phytoplankton form
the base of the
ocean’s
food web
Zooplankton
eat
Phytoplankton form
the base
the phytoplankton
Small
fish eat
of the ocean’s food
web
the zooplankton
Food Chain
•
• Zooplankton eat the
phytoplankton Large fish eat the
small fish and so on . . . .
• Small fish eat the zooplankton
• Large fish eat the small fish
and so on . . . .
What are phytoplankton?
Answer Bank
• Microscopic plants that produce ____ of the
worlds oxygen through photosynthesis
• They form the ____of the ocean’s food web
Green areas
Indicate
phytoplankton
Nutrient
50%
Open
Bottom
base
Upwelling
This cold deep water
contains high
concentrations of
nutrients
• Phytoplankton take
advantage of the nutrient
rich waters growing in
large numbers
• This results in an
increase in life along the
coast
Upwelling
• Upwelling is a
circulation in the ocean
where deep, cold water
replaces warm water
along the coast
• In upwelling, wind
blowing offshore or
parallel to the coast
carries water away
from the land
What is Upwelling?
• The movement of deep, cold and _____ rich
water to the surface due to winds forcing
water offshore
Answer Bank
Nutrient
50%
Open
Bottom
base
Summarize:
• Animals that live in the benthic zone live
on the _____ of the ocean and animals
that live in the pelagic zone swim in the
_______ ocean
• Phytoplankton produce ____ of the
worlds oxygen and are at the ____ of the
food chain
• _______ is the movement of cold
nutrient rich water to the surface
Answer Bank
50%
Open
Bottom(2)
upwelling
Topic: Salinity & Tides
• Objectives:
– I will understand ocean salinity and the amount
of dissolved salt in the ocean
– I will understand tides and what causes them
Salinity
• In sea water, the most abundant
elements are sodium and chlorine
• Sodium and Chlorine form
together to make a mineral called
halite or table salt to season our
food
• Rivers deliver these salts to the
ocean
• Salinity is the measure of the
amount of solids dissolved in sea
water
96.5% water
3.5% salt
What is the Salinity of ocean water?
• Ocean water consists of
___% water and ___%
salt (sodium chloride)
• High Evaporation rates
in the tropics increase
salinity in the ocean
Answer Bank
96.5
3.5
Tides
• If you ever visited
tide pools at the
beach, you know
that the best time to
go is at low tide
• You might have
even noticed the tide
rise and fall while
visiting the beach
• The rise and fall of
sea level is called a
tide
Tides
• The tide is
actually
caused by a
giant wave
• The moons gravitational pull causes a massive bulge,
or wave that pulls on the ocean as it orbits earth
• As the crest of the wave approaches the shore, what
kind of tide do you think we get?
What Causes the Tides?
• Put simply, the
gravitational effect of
the Moon and Sun
• Remember, gravity is
the mutual attraction
between two objects;
and the force between
the two objects
increases as their size
and mass increases
• Water responds to the
gravitational pull of the
Moon
What Causes the Tides?
• Two bulges of water
form, one directly
under the Moon and
one on the opposite
side of earth
• As the earth spins,
these bulges follow
the moon and its daily
movement
• As the earth rotates,
different locations on
Earth’s surface pass in
and out of high tide
A Wave that Represents Tide
-When is High Tide
-When is Low Tide
When is the biggest tides!
What are tides and how are they formed?
• Periodic rise and fall of the
water level in the oceans and
other large bodies of water
caused by a massive wave
created by the moon and
sun’s _______ pull
• Spring tides produce the
Highest and lowest tides and
occur when the sun and
moon are _____
• Neap tides produce small
changes in tides and occur
when the moon earth and sun
are at right angles to each
other
Answer Bank
96.5
gravitational
3.5
aligned
Summarize:
• The greatest tides (spring tide) occur when
the moon and ____ are aligned
• Smaller tides (neap tide) occur whe nte hsun
and moon are at ____ angles to each other
• Ocean water is made up of ___% salt and
___% water