Download Oceans - Learn with Mrs. Schulz

Water, water, everywhere,
And all the boards did shrink;
Water, water, everywhere,
Nor any drop to drink.
- Samuel Taylor Coleridge
The Rime of the Ancient Mariner
Possible Misconceptions
-Oceans are just like a huge lake, rarely moving
-NO! They are CONSTANTLY moving. The waves and currents at the
surfaces to the currents that are unseen underneath the surface.
-The different seas and oceans are separated from each other, that’s
why they have different names
-NO! Look at a globe or a map, they are all connected.
-The ocean is just good for swimming and has no effect on me, I live
in Alberta for crying out loud!
-NO! The ocean is a vast source of food (fish), petroleum products,
and others used commonly such as gelatin-like products used in
food.
-The ocean also affects the weather and rainfall of Alberta and the
rest of the world.
A Sea Full of Salt
-What is different between river and lake water and ocean water?
-How is this measured and what is the term for this measurement?
Salinity – the measurement of how salty water is
3.5% in seawater meaning 35g of dissolved salts in 1L of
water (35g/L)
density is 1.03g/mL on average though can get much denser up (to
1.5g/mL)
freezing point is -2 degrees Celsius due to high salt content which lowers
the freezing point
-The main component in sea water other than water is chloride followed
by sodium which is the same compound found in the salt on your table!
-There are other components as well that also combine to make salts.
-Where do these come from?? Sediments and minerals and salts from
the land washes out into the oceans. First proposed by Sir Edmond Halley.
Na also came from tectonic plates underneath seawater
Cl came from underwater hydrothermal vents and volcanic activity
Seawater composition
H20 96%
Cl 2%
Na 1%
Mg 0.13%
other: S, Ca, K,
Dead Sea in Israel
- has no outlet so salt builds up
in concentration
- -saltiest water on Earth
Other salty water
Great Salt Lake, Utah, USA
The Mysterious Ocean Floor
-Visible light is not able to pass more than about 100m into the ocean
so scientists had to develop different ways to discover what the ocean
floor, or ocean basins, looked like! (More later)
-There are 5 major features of the ocean floor:
1) Ocean Ridges – huge underwater mountain ranges which are the
youngest parts of the ocean floor and caused by volcanic eruptions.
2) Trenches – deep, narrow, steep-sided, canyons formed where a
continental plate meets an ocean plate. The opposite of an ocean
ridge.
3) Abyssal Plain – found between the ridges and trenches and are
formed of thick deposits of sediment from the continents.
4) Continental Shelf – part of the continent that is underwater. Exists
from the coastline to the ocean basin and gradually slopes
downward.
5) Continental Slope – the edge of the continental shelf that plunges
rapidly to the ocean basin.
How Does This Happen?
-There are no rivers, wind, rain, or ice on the bottom of
the ocean to erode and shape the rock.
-Instead the formations are made by tectonic plate
movements.
-Ridges as molten lava is forced out between two plates
and trenches as ocean plates move under continental
plates.
-Tectonic plates are constantly growing and shrinking.
-Sediments that form the abyssal plains is washed into
the ocean by rivers and then moves to the plains by great
underwater landslides and ocean currents.
-These landslides are started by earthquakes or gravity.
Wonderful Waves
-Waves are just ripples caused by steady ocean winds
-They begin at open sea and their size depends on how fast, long and
far the wind blows over the ocean.
-Even where there appears to be no wind there are still small waves
called swells which are caused by distant storms and winds.
-ALL waves (including sound, light, microwave, ect) have 3 properties
in common:
1) Height – measured from the crest to the trough
2) Wavelength- measured by the distance of one crest to the next.
3) Speed(Frequency) – measured by the time it takes for a wave to
pass a particular point
-Water particles move in a circular motion and stay in the relatively
same position as a wave passes.
-When a wave reaches the shore the trough is slowed by the friction
of the beach but the crest stays the same speed thus eventually
passing the trough and tumbling over. This is called a breaker.
Shorelines and Beaches
-Waves usually collide with the shore at an angle which causes
them to move along the shoreline creating a longshore current.
-These waves and currents have energy which is able to erode
and pick up sediment and carry it a distance away.
-The sea water is also capable of dissolving some minerals in
rock.
-Eventually the sediment is dropped.
-Waves continue to erode the pieces of sediment into finer
pieces which eventually becomes sand.
-Stronger waves and more steeply-sloped shorelines cause more
sediment to be washed back to sea and the opposite for weaker
waves and a gentle slope.
-Seaside communities value their beaches and use methods such
as building sea walls, breakwaters, and jetties to prevent strong
waves and longshore currents from washing away the sand.
Tides
http://www.montereyinstitute.org/noaa/lesson10.html
-The slow rise and fall of the ocean is called a tide
-Tides are controlled by the Moon’s gravitational pull.
-Spring Tides are the largest tidal movements and occur when
the Sun, Moon and Earth are all aligned.
-Neap Tides are the smallest tidal movements and occur when
the Sun and Moon are at right angles to each other.
-The difference between high and low tide is called tidal range.
-The Sun is further from the Earth than the moon thus it has
less influence on the tides, but when they are all aligned they
work together to create a bigger tidal range. When they are at
right angles the Sun works against the Moon’s gravitational
pull.
-At high
tide it may appear the volume of the ocean is
increasing but it is actually only being pulled towards the
one coast and away from the opposing coast.
-The side of the Earth facing the Moon is affected by its
gravity thus creating a bulge and pulling the water away
from the sides at right angles. Water on the opposite side
of the Earth that the Moon is facing also has a bulge.
-Two areas of high tide means that at least two high tides
and low tides per day are typical.
-The tidal range is also affected by the shoreline: narrow
opening then broad shoreline vs. broad opening and
narrow shoreline.
Currents
-Broad continuous movement of the ocean water is called a current.
-These currents are driven by the fairly constant wind patterns around
the world.
-Three factors influence the direction of winds and surface currents:
1) Uneven heating of the atmosphere – as the Earth is heated the warm
air expands creating a low pressure area. Cold air, which is high
pressure, moves into these areas of low pressure creating wind.
2) Rotation of the Earth – causes the Earth to move beneath the currents
(wind and water) causing them to turn. Causes equatorial winds to
blow from the east thus pushing ocean currents west – Trade winds.
Causes polar winds to blow from the west thus pushing ocean
currents east – Westerly winds.
3) The Continents – currents are forced to turn either north or south
when they hit a continent.
-The combination of all these factors keeps the currents circulating in a
specific way.
-The northern hemisphere circulates clockwise and counterclockwise in
the southern hemisphere.
Temperature and Currents
-If you were to graph the temperature of the ocean as you moved
deeper what would it look like?
-There are three distinct layers:
1) Mixed Layer – wind and currents mix the water on the surface so it is
all the same temperature. Relatively warm because of the Sun.
2) Thermocline – a region about 200m down where the Sun’s radiation
no longer reaches resulting in a rapid temperature decline.
3) Deep Water – water remains at a constant temperature just above
freezing.
Warm and Cold Currents
-Why is Northern Ontario so much colder than Britain when they are
equally far north?
-The current feeding into Hudson’s Bay and around Newfoundland
and Labrador comes from Baffin Bay up past Greenland.
-The current that brings water to the British Isles is called the Gulf
Stream and originates from Caribbean Sea.
-The temperature of the water drastically affects the climate of the
area.
-The currents are able to maintain their heat because water has a
very high specific heat capacity.
-This means that it takes a relatively long time to heat up or cool
down.
-The temperature of the water influences weather systems through
producing wind which alters condensation and evaporation.
Why is the
ocean warmer
at night??
-It’s not its just a trick your
body is playing on you!!
-This phenomena is also
part of the explanation on
how ocean currents and the
temperature of the water
affects the climate on the
land.
Exit Slip Time!!!
1) List three ways that the ocean
affects us here in Alberta
2) How did the ocean get salty and
why is it staying salty?
3) Draw and label 2 different sets of
waves going 2 different frequencies
4) Explain how the black sand beach
below could have been formed.
(Hint it’s NOT pollution)