Download Global Winds and Ocean Currents

Name___________________________
Date __________ Period____ Group____
Lab: Winds, Currents and Temperature
Part 1: Global Winds and Ocean Currents
Purpose: To demonstrate how winds influence surface currents.
Background Information: The surface currents of the major ocean basins show similarities to the
prevailing wind systems that drive them. Contained by continental boundaries and deflected by
the rotation of the Earth (Coriolis Effect), these surface currents flow in large, roughly circular
patterns called gyres. Gyres play an important role in redistributing heat from the low to middle
and high latitudes, thus influencing air temperature, weather, and climate.
Procedure:
1.
Fill the pie pan with water about half way. Let the water sit for about a minute so that it is
completely still.
2.
Sprinkle a few (15-20) of the paper circles on the top of the water.
3.
Have two people, one from the left and one from the right, blow through the straw as
shown below. You want to create a clockwise gyre. (Movement of the paper circles is
clockwise).
Straw
Straw
4.
5.
6.
Pie Pan
Repeat step 3 so that you produce a counterclockwise gyre.
Now move your straw to new locations until you find the best position to create two
gyres simultaneously in the dish.
When you are finished, DO NOT DUMP WATER DOWN THE DRAIN. Return water to
the front of the room to be filtered.
Questions:
1.
Draw a picture of the locations of the straws and use arrows to indicate the direction
wind movement and water movement below:
Clockwise
Counterclockwise
Two Gyres
2.
Based on the following map showing global wind patterns, predict the location of gyres in
the North and South Atlantic Oceans. Draw and label your prediction on the map below.
3.
At what latitude are your ocean gyres centered?
4.
What direction, clockwise or counterclockwise, does the gyre rotate in the Northern
Hemisphere?
5.
What direction, clockwise or counterclockwise, does the gyre rotate in the Southern
Hemisphere?
6.
In both the North and South Pacific Oceans, the gyre circulation transports warm water
from the equatorial regions toward the poles along which coast of the continents, east or
west?
7.
The same gyres transport cold water from the higher latitudes towards the equator along
which coast of the continents, east or west?
8.
What temperature water (in general) do you expect to flow along the California coast
line? Along the east coast of the United States?
Part 2: Ocean Currents and Coastal Temperatures
Purpose: To observe how currents affect the climate of two coastal cities, San Francisco,
California and Norfolk, Virginia.
Background Information: San Francisco and Norfolk are at approximately the same latitude,
thus the amount of solar energy they receive on a daily basis is approximately the same. During
the late spring, summer and early fall, a daily land/sea breeze is established due to differential
heating between the land and sea as shown below. Onshore winds occur during the day as the
land heats up. Offshore winds occur at night as cool air replaces warm air rising over the ocean.
Hypothesis: Which city, San Francisco or Norfolk, will have higher spring and summer
temperatures? Why?
Procedure:
1.
Record the starting temperature for the air in the classroom.
2.
Setup your ring stand with the clamps attached.
3.
Carefully place the two thermometers in the clamps
4.
Fill one cup with about 25 mL warm tap water and the other with about 25 mL cool tap
water.
5.
Cover each cup with the lid
6.
Insert the thermometers into the cups through the lids and record the temperature of the
air (not the water) in the two containers every minute for 10 minutes.
7.
While you are collecting your data, begin setting up Part 3 of the lab.
Extra Credit (to be done at home):
Find two coastal cities on another continent that have approximately the same latitude.
City #1___________________ City #2___________________ Latitude_________
Circle which city you think has the higher summer time temperatures. Find summer-time
climate information for these cities on the internet, in the newspaper, or an almanac. Was
your prediction correct? Attach your information to this paper when you turn it in.
Time
(minutes)
Temperature of
Warm Water
Container (ºC)
Temperature of
Time
Cool Water
(minutes)
Container (ºC)
6:00
0:00
1:00
7:00
2:00
8:00
3:00
9:00
4:00
10:00
Temperature of
Warm Water
Container (ºC)
Temperature of
Cool Water
Container (ºC)
5:00
Questions:
1.
Graph your data on the graph below.
2.
Which container had the highest temperature at the end of 10 minutes?
3.
Where do the currents that move past San Francisco come from? Are they warm or
cold?
4.
Where do the currents that move past Norfolk come from? Are they warm or cold?
5.
Which city would have the greater spring through fall temperatures? Why? Give a
thorough explanation based on the results of your experiment and the background
information given.
Temperature (degrees Celsius)
Temperature vs. Time
100
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
7
Time (min)
8
9
10
1
11
Part 3: Currents and Ocean Circulation
Purpose: In this activity you will look at the density differences of water based on temperature and
how this will affect ocean circulation patterns.
Background Information: Currents in the water change how the ocean water will circulate.
Currents are affected by local and global winds, the Coriolis force and landmasses. These currents
will affect the temperature of the air above landmasses; if a current is warm, it warms the air and
conversely if a current is cold, it cools the air. In a previous lab, you looked at the effect of salinity
on the density of ocean water. However, this is not the only factor that affects density; temperature
can also change the density of seawater.
Materials: lab tray with water, ice pack, zap packs, food coloring (your teacher has)
Hypothesis:
If you place a cold pack on one end of your tray of water and a zap pack (warm) on the
other end, what will happen to the drop of food coloring dropped at either end of the tray?
Procedure:
1. Fill the your white lab tray with about 3 cm of room temperature water (about half full).
2. Place the ice pack in the water against one end of the pan.
3. Activate the zap packs and place them in the water at the other end of the tray.
4. Record your prediction about what will happen when you complete step 4.
5. Squeeze a drop of food coloring in the water in front of the ice pack and another single drop
in a corner over the zap packs.
6. Observe the movement of the food coloring.
7. Record your observations.
8. If you have time, repeat the experiment to see if there is a different result.
9. Prepare the station for the next group by:
a. dumping the water out of the pan
b. making sure your lab table is dry
c. carefully place zap packs in the beaker of boiling water
Questions:
1. What happened to the drop of food coloring on the cold end of the tray?
2. What happened to the drop of food coloring on the warm end of the tray?
3. What does this tell you about the density of warm versus cold water?
4. Monterey Bay often has very cold nutrient rich water near the top of the bay giving rise to
the vast array of life found there. Using what you now know about wind, currents and
temperature, propose a reason for this cold, dense water to be so near the surface.