Chapter 7-2
Ocean Currents and Climate
What are currents and how do they affect us?
• Surface Currents: Are rivers of water moving through
the ocean.
– They travel to a depth of several hundred meters and are
driven by winds.
– Northern hemisphere currents move in a clockwise direction
and southern hemisphere in a counter-clockwise direction
– Currents affect the climates on the coast. NC’s coast is
warmer in the winter because warm waters heat up the air
and keep the climate warmer and in summer the cooler
waters cool the air and keep the climate cooler. (it acts like a
heater and AC)
What is the Gulf Stream?
• Most of the information known about currents was
gathered in the Gulf Stream by earlier sailors.
• It is located in the North Atlantic Ocean.
• It was discovered by Ponce de Leon in the 1500’s.
• It flows from Florida northeastward toward North
Carolina.
• It is a warm current because it originates near the
equator.
Current Discussion
• Why are currents along the eastern coasts of
continents usually warm while those along the
western coasts are cold?
– Currents along the eastern coasts originate at the
equator, where the amount of energy absorbed
from the Sun is the greatest; currents along
western coasts originate at high latitudes where
water receives less solar energy.
What are density currents?
• Density current: Form when more dense
seawater sinks beneath less dense coldwater.
• Seawater becomes more dense when it gets colder.
– Occur deep in the ocean where wind is not a
factor.
• Ex. Pg.205 in textbook.
– They act like a conveyer belt: cold water from the
ice caps on the bottom and warm water moving
on the top.
Density Current
Could density currents stop? How would this
effect climate?
• Yes, if Earth’s temperature rose enough, ice
would not form on the polar regions.
• In turn, their would not be any cold water supplying the
density current “conveyer belt”.
• This process could result in drastic climate
shift.
What is upwelling?
• Upwelling: A current in the ocean that brings,
deep cold water to the surface.
• Upwelling brings nutrients from the bottom of the
ocean to the top.
Do Now 11/18/09
• Answer the following questions in complete
sentences:
– What is salinity?
– How does oxygen get into sea water?
– What are the three levels of water temperature in
the ocean? Put then in order from most deep to
least deep.
Today's Routine
•
•
•
•
•
•
Do Now
Chapter 7-1 Reinforcement Handout
Chp.7-2 Notes
Chapter 7-2 Reinforcement Handout
Rap-up Session
Announcements
Homework
• Use your notes and textbook to complete the
following task:
– Create five questions that are not in the textbook
or your notes with the information learned in
chapter 7-1,7-2. Try to “stump” your classmates
with your questions. You may use the internet and
other resources to gain more knowledge on the
topics learned.