The World of Water
I. Earth is a water planet
a.More than 70% of the Earth’s
surface is water
b. 5 major oceans:
i. Pacific
ii. Atlantic
iii. Indian
iv. Southern
v. Arctic
II. The Salty Sea
a.Salinity – the amount of salt
dissolved in water
b. Surface Salinity: does not vary
much around the world
i. Variability:
1. Areas with high
evaporation and low
precipitation – HIGH
SALINITY
2. Areas with high
precipitation – LOW
SALINITY
c. Salinity & Ocean Depth
i. Variability:
1. Salinity increases with
depth
2. Not at a uniform rate
3. Halocline Layer – layer of
water that shows a rapid
increase in salinity; 100200 meters deep
III. Temperature: dependent upon
source
a.Equatorial Source: water currents
fed by equatorial regions are
warm
i. Example: The Gulf Stream
b. Polar Source: water currents fed
by polar regions are cold
i. Example: Atlantic Current &
North Pacific Current
c. Periodic shifts in prevailing winds
create changes in currents
i. El Niño – a warm current that
occurs during Christmas time
in the Pacific Ocean causing
devastation to cold water
species
d.Ocean movements are dependent
on temperature
i. Cold water is dense; sinks
ii. Warm water rises to the
surface
IV. Pressure
a.Sea Level: one “atmosphere” of
pressure is placed upon us at all
times
b. Ascend a mountain; pressure
decreases
c. Enter the ocean; each 33 feet of
depth pressure increases one
“atmosphere”
i. Humans tolerate pressure up to
a few hundred feet
ii. Marine organisms are also
dependent on pressure
1. Deep ocean organisms can
NOT survive at the
surface; Surface organisms
can NOT survive in the
deep
2. Some marine organisms
have very specific
adaptations that allow them
to move between pressure
extremes.