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WATER -- A GLOBAL, HUMAN
PERSPECTIVE
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Fig
5-2: Land and water hemispheres |
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The "water planet"
- Earth's surface
is more water than land -- about 75% is water
- Hold a globe in front of you and
focus on 145° W, 22.5° S!!
Forms of atmospheric
moisture
- What do we mean by "water"?
- Chemical formula for water = H2O
- Two atoms of Hydrogen and one of
Oxygen per water molecule
- But the chemical formula does not
designate which physical state of matter
- Physical "States" of water -- solid, liquid, gas
- Some questions about the physical
states of water to be answered int his chapter:
- Humidity (water vapor) -- Can we see it; "feel" it?
- Clouds -- what states of water?
- Fog -- How different than a cloud?
- Precipitation -- What states of water?
Water’s many roles
- Essential for life
- Required for all plants
- Natural distribution of water is
one determiner of types of native plants
- Many commercial crops must be
irrigated
- Required for all animals
- Humans build expensive and
elaborate domestic water supplies for cities
- Humans sell bottled water for
drinking
- A large percentage of plant and
animal tissues are comprised of water
- Temperature moderator
- Water is a cooling agent for
industrial processes
- Evaporative, "swamp box"
coolers serving as substitutes for true air conditioners
- Water is a space-heating medium
(buildings)
- Energy transfer medium
- Electricity production by burning
fossil fuels (coal, oil, natural gas) to produce steam (hot water vapor) to run turbines
to run generators
- Water falling by gravity flow at
dams produces hydroelectricity
- Raw material in manufacturing products
- "It's the water" (in
infamous amber fluids)
- A component of almost all
beverages
- A component of canned fruits and
vegetables
- A component in various chemical
products
- Solvent
- Water is a cleaning agent in
industrial processes
- Flotation agent
- Logs in a log pond at a sawmill
- Ships and barges travel in
waterways
- Human recreation
- Viewing beautiful water bodies
- Water sports
- Fishing
THE
HYDROSPHERE
- World's oceans
- Arctic
- Atlantic
- Indian
- Pacific
- Southern (Encircling the continent of Antarctica)
- Distribution of
global water among the "reservoirs" [F 5-3, p 139]
- The perspective
should be on the amount of "fresh" water
- Humans, land
animals and most plants need non-salty water
- Oceans comprise
97.2% of world's waters
- Fresh water =
2.8%
of world total
- Ground
water (including
deep) beneath the surface is 22% of freshwater
- Surface water
is 78% of freshwater
- 99.4% of
surface freshwater is locked up in the
solid state in ice sheets
and glaciers
- Antarctica
-- ice cap largest source, if melted
- Greenland
ice cap -- second largest source
- Lesser ice
sheets and mountain glaciers
- Freshwater
lakes comprise 0.33% of surface water
- Streams total
to 0.003% of world's surface water!
- Clearly, water to
supply human needs is very, very limited compared to total amount of
water on Earth
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Fig5-3:
Ocean and freshwater distribution on Earth |
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