Download The Water Planet

The Water Planet
Background
 Earth appears mostly blue from space because
oceans cover more than 70 percent of its
surface.
 For this reason, Earth is sometimes called the
water planet.
 The average depth of the oceans is more than
four times the average elevation of the
continents.
Importance of Oceanographers
• Map the ocean floor
• Track global ocean temperatures
• Study how humans affect oceans: pollution,
oil spills, deep-sea mining/drilling
• Understand the consequences of global air
temperature on water
Major Oceans
Properties of Ocean Water: Salinity
• Salinity – a measure of
the dissolved salts in
water.
• On average, 1000 grams
of seawater contains 35
grams of salt, or 3.5.
Variations in Salinity
• In deeper ocean waters, the salinity is close to
the average of 3.5 
• Near the surface, it can vary between 3.3 %
and 3.7 %.
• Salinity is below average in places where large
amounts of fresh water enter the ocean.
• Salinity is also lower in areas of heavy rainfall,
such as those near the equator.
• Salinity tends to be above average in areas
that are extremely hot.
• In hot, dry climates, the oceans lose water
rapidly through evaporation, leaving salts
behind.
– The Mediterranean Sea and the Red Sea can be as
high as 4 %.
– The Dead Sea has the highest salt concentration of
any sea in the world.
• Scientists believe the salt composition of the
oceans has not changed in the past 200
million years.
Properties of Ocean Water: Temperature
• Almost all the energy
that heats the oceans
comes from the Sun.
• But solar energy does
not penetrate very
deeply into the oceans.
• Ocean temperature
decreases rapidly with
depth.
Sea Level
• Sea level has risen and fallen by hundreds of
meters in response to melting ice during warm
periods and expanding glaciers during ice
ages.
• Tectonic forces (earthquake and volcanic
boundaries) also cause Earth’s crust to rise
and fall.
• Data shows that sea level rose at a rate of
about 3 mm per year between 1993 and 2004.
Properties of Ocean Water: Light Absorption
Properties of Ocean Water: Layering
• Ocean surface temperatures
range from -2 C (30 F) in
polar waters to 30 C (86 F)
in equatorial regions, with
the average surface temp
being 15 C (60 F).
• Deep ocean water is always
cold, even in tropical waters.