Motion in the Ocean
Ocean Currents
• Warm currents
flow AWAY
from the
equator and
towards the
poles
• Cold currents
flow TOWARDS
the equator
from the poles
Why is Ocean Circulation Important?
 It transports heat from the equator to the
poles
 It transports nutrients and organisms – it
returns oxygen to the system and stirs up
food from bottom
 It influences weather and climate
 It influences commerce
What are Currents?
 Ocean currents are rivers of circulating waters found
in the ocean
 There are two types:
 Surface Currents- the upper 400m of the ocean (10%)
 Deep Water Currents- Thermal/Salinity currents (90%)
Surface Ocean Currents
 Make up 10% of the oceans’
waters
 Up to a maximum depth of
400 meters
 Broad, slow drifts that
NEVER cross the equator
 Mostly wind generated
 Create gyres- enormous
circular currents
Importance of Surface Currents
 Migration
 Navigation
 Weather
Deep Ocean Currents
 Makes up about
90% of the oceans’
water
 Differences in
density are related
to salinity and
temperature
which causes the
waters to move up
or down beneath
the ocean
Thermohaline Circulation
 Global ocean circulation that is driven by differences
in densities of the sea water which is controlled by:
 Temperature
 Salinity (salt)
Importance of Deep Ocean Currents
 Upwelling
 Movement of deep
water to surface
 Hoists cold, nutrientrich water to surface
 Produces high
productivities and
abundant marine life
Factors Influencing Currents
 The Wind
 Just as wind moves from
high pressure to low
pressure, so do our
waters
 Winds blow across the
surface creating friction
and motion
 The water piles up
because the water
currents flow slower
than the winds
Factors Influencing Currents
 The Sun
 heats the water
making it less
dense and
creating a
convection
current in the
ocean
 Factor also
referred to as
water density
Factors Influencing Currents
 Water’s Salinity Salinity means salt
content
 Saltwater is more
dense, so it sinks
lower than fresh
water
Factors Influencing Currents
 The Coriolis Effect
 Causes water to
move right in the
Northern
Hemisphere
(clockwise)
 Causes water to
move left in the
Southern
Hemisphere
(counter-clockwise)
Reflective Questions?
 1. How are ocean currents produced?
 2. Where do cold currents come from?
Where do warm currents come from?
 3. How do ocean’s impact climate?