What’s the story?
Oceanic Water
•Horizontal and vertical spatial
variations in the temperature
and salinity of ocean water.
What do you
think affects
ocean
temperatures?
What affects ocean
temperatures?
1. Latitude
2. Seasonal
changes (tilt
of the Earth)
3. Ocean depth
4. Salinity
5. Transfer of
energy
(through
winds/ocean
currents)
Horizontal spatial variations Annotate your map to show
(1) global variations in sea surface temperatures (2) the impact of ocean currents
(look at the differences on the East and West sides of the continents)
Annotate your map to show
(1) global variations in sea surface temperatures (2) the impact of ocean currents
(look at the differences on the East and West sides of the continents)
(1) Sea surface temperature varies according to latitude – it is much warmer
nearer to equatorial regions than in the poles
(2) On the Western sides of continents, the cooler waters from ocean currents
can be seen intruding towards the equator. Similarly (if not quite so clearly),
the warmer waters of ocean currents flowing from the equatorial regions can
be seen on the eastern side of several continents)
Vertical spatial variations in
ocean waters
• Ocean water varies considerably with
depth – two of the considerable
variations are:
• Temperature
• Salinity (how salty the water is)
How does ocean water temperature
change with depth?
Tasks:
1. Draw a sketch of the
graph
2. Describe what happens
to ocean water
temperatures with
increasing depth
Between summer and winter,
the ocean temperature change
varies quite significantly
between 500-1000m deep.
Below this level the
temperature decline is much
slower.
Thermocline
• Definition: the zone of
rapid temperature change
in a vertical body of water.
In the oceans the boundary
usually occurs between
200m and 800m.
• Approx. 90% of ocean
water is found below the
thermocline. Generally the
surface waters do not mix
with the deeper layers.
As oceans get deeper...
• Temperature decreases
• BUT...
• Salinity increases
• Water density increases
How does ocean water salinity
change with depth?
• Halocline - the zone
of rapid salinity
change in a vertical
body of water. In
the oceans the
boundary usually
occurs between
200m and 800m
which is in a similar
region to the
thermocline.
What is the relationship between
temperature, salinity and water
density in the oceans?
Temperature
High
Cold water is denser than warm water
+
Saltier water is also denser
+
Temperature decreases with depth
+
Salinity increases with depth
=
An increase in water density as depth
increases
Low
Low
Salinity
High
How does ocean water density
change with depth?
• Pycnocline - the zone
of rapid water
density change in a
vertical body of
water. In the
oceans the boundary
usually occurs
between 200m and
800m which is in a
similar region to the
thermocline and
halocline.
A few things to note...
• The changes are seen more sharply in
tropical areas than in polar regions
because the surface temperatures are
warmer near the equator
• At great depths there is very little
change in temperature between the
equator and the poles
Where in the world can you
find...?
•
•
•
•
•
•
The warmest waters?
The coldest waters?
The saltiest waters?
The least salty water?
The water with the highest density?
The water with the lowest density?