Chapter 9
The Hydrosphere
The Hydrosphere
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Nature of Water
The Hydrologic Cycle
The Oceans
Permanent Ice
Surface Waters
Underground Water
Water is critical to every living
organism in the biosphere!
Water is a part of all living things on earth. There is even water in rocks.
Earth Moisture Inventory
Three States of Water
A Water Molecule - Sticky Water
H = 1 electron
Not satisfied, it needs 2
O = 8 electrons
Not satisfied, it needs 10
Each H atom shares its 1 e
with O, and O shares 1 of its 6
outer e’s with H
NOW BOTH ARE SATISFIED
Water Properties
• Sticky – surface tension
• Holds heat or cold
• Is liquid at normal temperatures
• Excellent solvent
• Is subject to gravity, but can move
upwards – capillary action
Hydrologic Cycle
• Evaporation
• Transpiration
• Vertical & Horizontal Transport
Earth has had the same amount of moisture for 100,000’s
of years. But, it is not always stored in the same form
(state).
It can be stored as liquid, as vapor or as ice.
Hydrologic
Cycle
The annual precipitation for earth is more than 30
times the atmosphere's total capacity to hold water.
This indicates the rapid recycling of water that occurs
between earth's surface and the atmosphere.
.001 %
2.4 %
97.5 %
Evaporation
• Water is transferred from the
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surface to the atmosphere.
It is the process by which
water changes from a liquid
to a gas.
Approximately 80% of all evaporation is from the oceans, the
remaining 20% from inland water and vegetation.
Winds transport evaporated water around the globe.
Transport influences the humidity of the air throughout the
world.
Condensation
• The change of water
from its gaseous form
(water vapor) into
liquid water.
• Generally occurs in
the atmosphere, when warm air rises, cools and
loses its capacity to hold water vapor.
• As a result, excess water vapor condenses to form
cloud droplets.
Transport by
Advection
• The movement of water
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through the atmosphere,
specifically from over the
oceans to over the land.
Some of the earth's moisture transport is visible
as clouds, which consist of ice crystals and/or
tiny water droplets.
Clouds are propelled from one place to another
by the Jet Stream or surface-based circulations.
Most water is transported in the form of water
vapor.
Precipitation
• The primary mechanism for transporting water
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from the atmosphere to the surface of the earth.
There are several forms of precipitation:
- rain (most common United States)
- hail
- snow
- sleet
- freezing rain
Hydrologic Cycle Definitions
• Evaporation: the conversion of liquid water on
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Earth’s surface lifted into the atmosphere as a
gas.
Advection (transport): transport of water
vapor around the globe in the atmosphere
Precipitation: transfer of water from the
atmosphere back to earth.
Ground transport: movement of water on
surface and underground (always trying to get
back to the ocean)
The Hydrologic Cycle
Vertical:
•Evaporation
•Transpiration
•Precipitation
Horizontal:
•Transport = Advection
•Surface Runoff
•Sub-surface run-off
Moisture Balance
Oceans Versus Continents
Oceans
Characteristics:
4 Oceans:
– Pacific
– Atlantic
– Indian
– Arctic
– Density: varies with temp,
salinity, and depth
– Temp: 80°F at the equator to
28°F in Arctic & Antarctic
– Salinity: chemical = 35ppt
Movement:
– Tides: 6 hrs/day water rises &
6 hrs/day water falls
– Currents: variety of currents
shift water vertically and
horizontally
– Waves: movement of energy
more than matter
Oceans and Seas
Figure 9-6
Permanent Ice
• Ice on land:
– Glaciers
– Permafrost
• Ice floating on ocean:
Glaciers
Extent of
Permafrost
• Encircles the North Pole
• Continuous permafrost at
60°N and higher
Earth’s Largest
Ice Pack
•No land/continent
under the Arctic
•It is ice floating on
water
Surface Water
• Lakes:
– not permanent features
– Not made by, but maintained by streams
– Fresh water and salt water
• Swamps & Marshes:
– Closely related to lakes, but less numerous and
contain less water
– Swamps have trees
– Marshes have grasses and rushes
• Rivers & Streams:
– Any flowing water is a stream
– Dynamic component of the hydrologic cycle
World’s Largest Lakes
Major Drainage Basins
Figure 9-18
Underground Water
• More than 2.5 times that contained in lakes &
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streams
More widely distributed
Porosity is percentage of pores (spaces)/total
volume of matter. The more porous the material,
the more water it can hold.
Aquifers and Aquicludes
Zone of Saturation
– Water Table
– Cone of Depression
• Zone of Confined Water
• Artesian Systems
• The Ogallala Aquifer
Aquifer
• Underground
water is stored in,
and moves slowly
through permeable
rocks.
• This layer is called
an aquifer.
• Rate of flow varies
with situation.
Aquiclude
• Impermeable
materials i.e., clay
or very dense
rock, prevent
water movement
• This layer is an
aquiclude.
Zones
• Zone of Aeration:
– Closest to the surface
– Contains clay particles and soil moisture
• Zone of Saturation:
– Below zone of aeration
– All openings in bedrock or sediments are saturated
with water
• Zone of Confined Water:
– below zone of saturation
– Impermeable layer – aquiclude – below surface
prevents water from percolating down
– Water comes in from the sides
• Waterless Zone:
– Overlying pressure increases density of rock to the
point that no pores exist – no room for water.
Cone of Depression
• In the zone of saturation
• Well fills with water to level of water table
• If water removed faster than replenished,
it collapses
Artesian System
• Dug below aquiclude
• Confined aquifer
• Pressure forces water up
Artesian Well
The Ogallala Aquifer
• Classic example of ground water
mining
• Largest U.S. aquifer
• Located southern & central Great
Plains
• Water accumulating for 30,000
years
• In 1950, it contained 456 trillion
gallons of water
• It will be dry in 10 – 50 years,
depending on location