9A_2 – Slide 1
Topic 9A:
Ocean Currents, Part II
Online Lecture:
Effects of Ocean Currents
○ Climate
○ Life in the Ocean:
Upwelling &
Downwelling
Ocean Currents and Climate
○ Warm water warms the air above it,
& cold water cools the air above it.
9A_2 – Slide 2
California
Current
○ More water evaporates from
warm water,so the air over
warm water is more humid
(“moister”) than the air over cold water.
○ How does the California Current
affect our climate?
Gulf
Stream
leading to more rain
cooler & dryer
○ How does the Gulf Stream affect the climate
of the east coast of the United States?
warmer &
more humid
In other words, do the California Current and Gulf Stream make
us warmer or cooler than we would be if they did not exist?
make our air more or less humid?
Upwelling & Downwelling
Sea Surface vs.
Deeper Water
9A_2 – Slide 3
○ Upwelling: deep water rising up to the surface to fill in
the “gap” at the surface created by currents moving apart
○ Downwelling: surface water sinking (going down) owing to
the additional pressure caused by water “piling” up when
currents come together
Hill
In this case, rising & sinking are
NOT due to the water’s density!!!
"Gap"
Downwelling
Upwelling
Effects of Upwelling on the Surface Water
9A_2 – Slide 4
Temperature: Warmer or Colder?
Colder
Salinity: Fresher or Saltier?
Saltier
Brings Up Nutrients:
More Life or Less Life?
More Life
Why
more
life?
Figure 13.5
on p. 393
Where is Upwelling Common in the Ocean?
○ near west coasts
(in the subtropics)
○ at the Equator
○ in the middle of the
Antarctic Ocean
Land
Upwelling
California
Land
Equator
Upwelling
9A_2 – Slide 5