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The Hydrosphere ART9.1
Question
1. How much of the Earth’s mass
is in the hydrosphere?
2. How much of the Earth’s
surface is covered in oceans?
3. How much of the Earth’s water
is found in oceans, and in ice?
4. What other bodies in the solar
system have hydrospheres?
5. How does the size of Europa’s
hydrosphere compare to Earth’s?
6. How long do different parts of
the cryosphere last?
7. Where is most of the world’s
ice?
8. What happens to ocean levels
as ice melts?
9. Where does the salt in the
ocean’s come from?
10. How is salinity expressed?
11. What is the average, and range
of salinity in the ocean’s?
12. What is the salinity of
freshwater?
13. What are ocean currents?
14. What are some of the more
prominent currents?
15. What causes surface currents?
16. Which direction do gyre’s turn?
17. What creates mounds in the
ocean’s surface?
Name: _____________________________ Period: ______
Answer
The Hydrosphere ART9.1
18. Where are deep water currents
found?
19. What causes differences in
density of ocean water?
20. Why is thermohaline circulation
is known as the Global Conveyor
Belt?
21. Why are ocean currents
important to the world’s weather?
22. Why are places like Europe
warmer than other areas at similar
latitudes?
23. What moves icebergs into
shipping lanes in the North Atlantic
shipping lanes?
24. How could ocean currents be
used to generate energy?
Using the articles, define the following terms:
1. salinity
2. cryosphere
3. hydrosphere
4. brackish water
5. osmosis
6. surface currents
7. gyre
8. thermohaline circulation
Name: _____________________________ Period: ______
The Hydrosphere
liquid. Some people fear that global
warming will cause the melting and collapse
of large ice sheets resulting in sea level rise.
Rising sea levels could devastate coastal
cities, displace millions of people, and
wreak havoc on freshwater systems and
habitats.
Hydrosphere
by Jerry Coffey
Liquid water makes up a large potion of the
hydrosphere.
A hydrosphere in physical geography
describes the combined mass of water found
on, under, and over the surface of a planet.
The total mass of the Earth’s hydrosphere is
about 1.4 × 1024 grams, which is about
0.023% of the Earth’s total mass. Around 2
× 1019 grams of this is the Earth’s
atmosphere. In addition, 71% of the Earth’s
surface, an area of 361 million square
kilometers, is covered by ocean.
Having liquid water makes the Earth a
special place. Our planet has a very nice
temperature range that allows water to
remain in its liquid state. If we were a colder
object like Pluto, it would not matter how
much water there was on the planet; it would
all be frozen. On the other hand, if we were
on a very hot planet, all of the water would
be in a gaseous state. Water vapor and solid
water are useless to the living organisms
found on Earth.
The world’s oceans contain 97% of the
water in the hydrosphere, most of which is
salt water. Ice caps, like that found covering
Antarctica, and glaciers that occupy high
alpine locations, compose a little less than
2% of all water found on earth. Although
that is a small amount, the water stored as
ice in glaciers would have a great impact on
the environment if it were to melt into a
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The Earth is not the only solar body that is
thought to have a hydrosphere. A thick
hydrosphere is thought to exist around the
Jovian moon Europa. The outer layer of this
hydrosphere is almost entirely frozen, but
current models predict that there is an ocean
up to 100 km in depth underneath the ice.
This ocean remains in a liquid form due to
the tidal flexing of the moon in its orbit
around Jupiter. The volume of Europa’s
hydrosphere is 3×1018 meters cubed, which
is about 2.3 times that of the Earths’
hydrosphere. It has been theorized that the
Jovian moon Ganymede and the Saturn
moon Enceladus may also possess subsurface oceans.
The hydrosphere is a delicate aspect of the
Earth. Many things have to remain in
balance in order for it to remain in stasis.
There needs to be more study to extrapolate
a definite cause and effect between the
hydrosphere and global warming.
Cryosphere
by Jerry Coffey
The cryosphere is the portions of the Earth’s
surface where water is in solid form,
including sea ice, lake ice, river ice, snow
cover, glaciers, ice caps, ice sheets, and
frozen ground like permafrost. Due to its
very nature the cyrosphere is always
changing in its area and volume and
overlaps quite a bit with the hydrosphere.
This is an integral part of the global climate
system. It has important linkages and
feedbacks generated through its influence on
surface energy and moisture fluxes, cloud
formation, precipitation, and atmospheric
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and oceanic circulation. This means that it
plays an important role in the global climate.
The two previous articles reprinted with permission
of : Universe Today. www.universetoday.com
Ocean Water: Salinity
Office of Naval Research
The residence time of water in each subsystem(snow, ice, permafrost) varies widely.
Snow cover and freshwater ice are
essentially seasonal. Most sea ice, except for
ice in the central Arctic, lasts only a few
years if it is not seasonal. A water particle in
a glacier, ice sheet, or ground
ice(permafrost) may remain frozen for 10100,000 years or longer, and deep ice in
parts of East Antarctica may have an age
approaching 1 million years. Most of the
world’s ice volume is in Antarctica, but by
area Northern Hemisphere winter snow and
ice is the largest, amounting to an average
23% of hemispheric surface area in January.
The large area and the important climatic
roles of snow and ice, indicate that the
ability to observe and model snow and icecover extent, thickness, and radiative and
thermal properties is of particular
significance for climate research.
The cryosphere is the part of the atmosphere
that shows some of the most easily
observable effects of global warming. As the
oceans warm, the ice recedes. The melting
ice can raise the levels of the oceans around
the world. It is actually a cycle. As the ice
melts it allows the planet to stay warmer and
more ice melts. NASA satellites have
documented a rapid decrease in ice sheets
that coincides with a rapid rise in global sea
levels.
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Did you ever wonder why the oceans are
filled with salt water instead of fresh? Just
where did the salt come from? And is it the
same salt you find on a dining room table?
Most of the salt in the oceans came from
land. Over millions of years, rain, rivers, and
streams have washed over rocks containing
the compound sodium chloride (NaCl), and
carried it into the sea. You may know
sodium chloride by its common name: table
salt! Some of the salt in the oceans comes
from undersea volcanoes and hydrothermal
vents. When water evaporates from the
surface of the ocean, the salt is left behind.
After millions of years, the oceans have
developed a noticeably salty taste.
Different bodies of water have different
amounts of salt mixed in, or different
salinities. Salinity is expressed by the
amount of salt found in 1,000 grams of
water. Therefore, if we have 1 gram of salt
and 1,000 grams of water, the salinity is 1
part per thousand, or 1 ppt.
The average ocean salinity is 35 ppt. This
number varies between about 32 and 37 ppt.
Rainfall, evaporation, river runoff, and ice
formation cause the variations. For example,
the Black Sea is so diluted by river runoff,
its average salinity is only 16 ppt.
Freshwater salinity is usually less than 0.5
ppt. Water between 0.5 ppt and 17 ppt is
called brackish. Estuaries (where fresh river
water meets salty ocean water) are examples
of brackish waters.
Most marine creatures keep the salinity
inside their bodies at about the same
concentration as the water outside their
bodies because water likes a balance. If an
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animal that usually lives in salt water were
placed in fresh water, the fresh water would
flow into the animal through its skin. If a
fresh water animal found itself in the salty
ocean, the water inside of it would rush out.
The process by which water flows through a
semi-permeable membrane (a material that
lets only some things pass through it) such
as the animal's skin from an area of high
concentration (lots of water, little salt) to an
area of low concentration (little water, lots
of salt) is called osmosis.
This is also why humans (and nearly all
mammals) cannot drink salt water. When
you take in those extra salts, your body will
need to expel them as quickly as possible.
Your kidneys will try to flush the salts out of
your body in urine, and in the process pump
out more water than you are taking in. Soon
you'll be dehydrated and your cells and
organs will not be able to function properly.
Ocean Currents
From Amanda Briney
Ocean currents are the vertical or horizontal
movement of both surface and deep water
throughout the world’s oceans. Currents
normally move in a specific direction and
aid significantly in the circulation of the
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Earth’s moisture, the resultant weather, and
water pollution.
Oceanic currents are found all over the
globe and vary in size, importance, and
strength. Some of the more prominent
currents include the California and
Humboldt Currents in the Pacific, the Gulf
Stream and Labrador Current in the Atlantic,
and the Indian Monsoon Current in the
Indian Ocean. These are just a sampling of
the seventeen major surface currents found
in the world’s oceans.
In addition to their varying size and strength,
ocean currents differ in type. They can be
either surface or deep water.
Surface currents are those found in the upper
400 meters (1,300 feet) of the ocean and
make up about 10% of all the water in the
ocean. Surface currents are mostly caused
by the wind because it creates friction as it
moves over the water. This friction then
forces the water to move in a spiral pattern,
creating gyres. In the northern hemisphere,
gyres move clockwise and in the southern
they spin counterclockwise. The speed of
surface currents is greatest closer to the
ocean’s surface and decreases at about 100
meters (328 ft) below the surface.
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Because surface currents travel over long
distances, the Coriolis force also plays a role
in their movement and deflects them, further
aiding in the creation of their circular
pattern. Finally, gravity plays a role in the
movement of surface currents because the
top of the ocean is uneven. Mounds in the
water form in areas where the water meets
land, where water is warmer, or where two
currents converge. Gravity then pushes this
water down slope on the mounds and creates
currents.
Deep water currents, also called
thermohaline circulation, are found below
400 meters and make up about 90% of the
ocean. Like surface currents, gravity plays a
role in the creation of deep water currents
but these are mainly caused by density
differences in the water.
Density differences are a function of
temperature and salinity. Warm water holds
less salt than cold water so it is less dense
and rises toward the surface while cold, salt
laden water sinks. As the warm water rises
though, the cold water is forced to rise
through upwelling and fill the void left by
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the warm. By contrast, when cold water
rises, it too leaves a void and the rising
warm water is then forced, through
downwelling, to descend and fill this empty
space, creating thermohaline circulation.
Thermohaline circulation is known as the
Global Conveyor Belt because its circulation
of warm and cold water acts as a submarine
river and moves water throughout the ocean.
Finally, seafloor topography and the shape
of the ocean’s basins impact both surface
and deep water currents as they restrict areas
where water can move and "funnel" it into
another.
Because ocean currents circulate water
worldwide, they have a significant impact
on the movement of energy and moisture
between the oceans and the atmosphere. As
a result, they are important to the world’s
weather. The Gulf Stream for example is a
warm current that originates in the Gulf of
Mexico and moves north toward Europe.
Since it is full of warm water, the sea
surface temperatures are warm, which keeps
places like Europe warmer than other areas
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at similar latitudes.
The Humboldt Current is another example
of a current that affects weather. When this
cold current is normally present off the coast
of Chile and Peru, it creates extremely
productive waters and keeps the coast cool
and northern Chile arid. However, when it
becomes disrupted, Chile’s climate is altered
and it is believed that El Niño plays a role in
its disturbance.
Whether ocean currents are used as
alternative energy, to reduce shipping costs,
or in their natural to state to move species
and weather worldwide, they are significant
to geographers, meteorologists, and other
scientists because they have a tremendous
impact on the globe and earth-atmosphere
relations.
Like the movement of energy and moisture,
debris can also get trapped and moved
around the world via currents. This can be
man-made which is significant to the
formation of trash islands or natural such as
icebergs. The Labrador Current, which
flows south out of the Arctic Ocean along
the coasts of Newfoundland and Nova
Scotia, is famous for moving icebergs into
shipping lanes in the North Atlantic.
Currents play an important role in
navigation as well. In addition to being able
to avoid trash and icebergs, knowledge of
currents is essential to the reduction of
shipping costs and fuel consumption. Today,
shipping companies and even sailing races
often use currents to reduce time spent at
sea.
Finally, ocean currents are important to the
distribution of the world’s sea life. Many
species rely on currents to move them from
one location to another whether it is for
breeding or just simple movement over large
areas.
Today, ocean currents are also gaining
significance as a possible form of alternative
energy. Because water is dense, it carries an
enormous amount of energy that could
possibly be captured and converted into a
usable form through the use of water
turbines. Currently this is an experimental
technology being tested by the United
States, Japan, China, and some European
Union countries.
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