Hydrosphere ES 4th Quarter
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Transcript of Hydrosphere ES 4th Quarter
HydrosphereBlastoise used surf!
Oceanography
• Composite science that draws methods and
knowledge from biology, chemistry, physics, and
geology to study all aspects of our world’s
oceans.
Some Boring Numbers
• The area of the earth is 510M km2
• The area of the oceans and marginal seas is
360M km2
• The area of the continents is 150M km2
• The northern hemisphere is 61% water and 39%
land
• The southern hemisphere is 81% water and
19% land
The World’s Oceans
• Pacific▫ Largest; Bigger than the Atlantic plus the Indian
Ocean.
▫ Slightly more than ½ of the world’s waters
• Atlantic▫ Center of a nearly parallel continental margin
▫ Shallowest
• Indian▫ Smallest
▫ Southern Waters
Comparison of Oceans and
Continents• Volume – all land is just one eighteenth that of
the oceans
• Relative levels (elevation, depth)
▫ The average elevation above sea levels is 840
meters
▫ The average depth of the ocean is 3800 meters
Physical Properties of Sea Water
• Composition
• Salinity
• Light Penetration Zones
• Temperature
• Pressure
• Density
Composition
Salinity
• Salt content in water
• Average for:
▫ Salt Water
30 – 35 ppt
▫ Brackish Water
0.5 – 18 ppt
▫ Fresh Water
< 0.5 ppt
Light Penetration Zones
Temperature
• Temperature layers
• The effect of
salinity and pressure is the
same for every
temperature
Water Pressure
• Pressure – a force that acts on an area
• Pressure increases by one atmosphere every 10
meters in depth in the water column
• One atmosphere is 14.7 pounds per square inch
Density
• The average sea water density is 1027 kg/m3
• There are 2 main factors that make more or less
dense than 1027 kg/m3
• These are temperature and salinity
• Cold water is denser than warm water
• Saltier water is denser than fresh water
• Temperature has a greater effect on density than
salinity
Motions of the oceans
• Currents
• Waves
• Tides
Currents
• Ocean currents move water continuously along
specific pathways, often across vast distances.
• This happens both on the surface and in the
deep ocean.
• Currents are driven by the wind across the
ocean’s surface.
Current Facts
• Persistent, dominantly horizontal flow
• Heat exchange between the poles and the
equator
• Surface currents are powered by the wind
• Gyres – circular movement of a large ocean
current
• Transports organisms, nutrients and pollution
across vast distances
Tides
• Is the rise and fall of sea levels caused by the
combined effects of the gravitational forces
exerted by the moon and the sun and the
rotation of the earth.
Waves
• Factors that affect the waves
▫ Speed of the wind
▫ Time of the wind
▫ Distance of the wind (fetch)
• Fetch
▫ the length of water over which a given wind has
blown