- Exploring Convection Currents Lab Activity
Objective:
To construct several models to demonstrate the principle of the convection, and to use your observations to explore the role convection plays in the development of atmospheric circulation and ocean currents.
To construct several models to demonstrate the principle of the convection, and to use your observations to explore the role convection plays in the development of atmospheric circulation and ocean currents.
Materials Needed per Lab Group
1 clear Plastic Box
1 Beaker: 50 ml
1 pipette
6 Styrofoam Cups
1 clear Plastic Box
1 Beaker: 50 ml
1 pipette
6 Styrofoam Cups
Food Coloring
Water ( Hot and cold)
Ice Cubes
Colored Pencils
Water ( Hot and cold)
Ice Cubes
Colored Pencils
Pre-Lab Question:
1. Conduction- The transfer of heat by touching
Convection- The transfer of heat in fluid that rises due to density differences
Radiation- The transfer heat by infrared waves
2. If one beaker contains 100ml of cold water and another contains 100ml of hot water, which beaker contains more molecules? Explain.
Cold water is more molecules because cold water is more dense than Hot Water.
3. Which water, hot or cold, would have the higher mass? Which would have the higher density?
Cold water have the higher mass; Cold water have higher density
4. As you open a refrigerator door, what happens to air inside?
The cold air escapes from the bottom, sinking toward the floor
5. As you lift the lid from a pot of soup, do the gases that escape rise from the pot, or sink around it's base? Why
The gases that escape rise from the pot because hot air is less dense
6. If you swim to the bottom of the a pool and place a cork on the bottom, will the cork stay in place? Why or Why not? Explain
No, because the water is more dense.
7. Both air and water are fluids. What will happen to the area within a fluid that becomes warmer than the surrounding fluid?
Low pressure, pull the air to the middle.
8. Atmospheric pressure is the pressure exerted on the earth by the force of the gravity pulling the air towards the earth's surface. Where air is raising from the surface, will be atmospheric pressure be increased or decreased?
Atmospheric pressure be decreased.
1. Conduction- The transfer of heat by touching
Convection- The transfer of heat in fluid that rises due to density differences
Radiation- The transfer heat by infrared waves
2. If one beaker contains 100ml of cold water and another contains 100ml of hot water, which beaker contains more molecules? Explain.
Cold water is more molecules because cold water is more dense than Hot Water.
3. Which water, hot or cold, would have the higher mass? Which would have the higher density?
Cold water have the higher mass; Cold water have higher density
4. As you open a refrigerator door, what happens to air inside?
The cold air escapes from the bottom, sinking toward the floor
5. As you lift the lid from a pot of soup, do the gases that escape rise from the pot, or sink around it's base? Why
The gases that escape rise from the pot because hot air is less dense
6. If you swim to the bottom of the a pool and place a cork on the bottom, will the cork stay in place? Why or Why not? Explain
No, because the water is more dense.
7. Both air and water are fluids. What will happen to the area within a fluid that becomes warmer than the surrounding fluid?
Low pressure, pull the air to the middle.
8. Atmospheric pressure is the pressure exerted on the earth by the force of the gravity pulling the air towards the earth's surface. Where air is raising from the surface, will be atmospheric pressure be increased or decreased?
Atmospheric pressure be decreased.
Set A
1. Fit two plastic lids on each of 9 Styrofoam cups. Set the clear plastic box onto the four Styrofoam cups
as shown in figure 2. Carefully fill the box with cold tap water to within 3-4 cm from the top. Let the
water calm before proceeding.
2. Using the pipette, carefully place 3 spots of red food coloring on the bottom of the box as shown in
figure 2. Insert the pipette all the way down to the bottom of the box before squeezing out the dye. Each
spot should be about 2-4 cm in diameter. Try to minimize disturbing the water as you insert and remove
the pipette.
3. Fill one empty Styrofoam cup with hot water and then carefully position it beneath the center dye spot.
The plastic lid spacers you fitted on the corner cups should provide you with enough clearance to gently
slide the cup with to water under the spot.
1. Fit two plastic lids on each of 9 Styrofoam cups. Set the clear plastic box onto the four Styrofoam cups
as shown in figure 2. Carefully fill the box with cold tap water to within 3-4 cm from the top. Let the
water calm before proceeding.
2. Using the pipette, carefully place 3 spots of red food coloring on the bottom of the box as shown in
figure 2. Insert the pipette all the way down to the bottom of the box before squeezing out the dye. Each
spot should be about 2-4 cm in diameter. Try to minimize disturbing the water as you insert and remove
the pipette.
3. Fill one empty Styrofoam cup with hot water and then carefully position it beneath the center dye spot.
The plastic lid spacers you fitted on the corner cups should provide you with enough clearance to gently
slide the cup with to water under the spot.
4. Now position yourself so that you can view the box from the side at eye level, and observe what
happens to the 3 spots over the next 5 minutes. Be sure to look for changes in all 3 spots. Write your
observations below.
5. Describe what you observed
6. Using two hands under the box, carefully, empty the water into a sink and begin Setup B
happens to the 3 spots over the next 5 minutes. Be sure to look for changes in all 3 spots. Write your
observations below.
5. Describe what you observed
6. Using two hands under the box, carefully, empty the water into a sink and begin Setup B
. The food color is floated to the surface , the food color move to the both side and after 5 minute the water into the box is conversion to red.
Setup B
1. Repeat procedures 1 & 2 from Setup A to set up the box one again.
2. This time, fill two cups with hot water and position them beneath the two outside spots. Observe what
happens over the next 10 minutes, and then sketch what you observed in Diagram 2 below. Be sure to
look for changes in the middle spot. Use arrows to show direction of flow.
3. Carefully empty the water from the box into a sink, and begin Setup C.
1. Repeat procedures 1 & 2 from Setup A to set up the box one again.
2. This time, fill two cups with hot water and position them beneath the two outside spots. Observe what
happens over the next 10 minutes, and then sketch what you observed in Diagram 2 below. Be sure to
look for changes in the middle spot. Use arrows to show direction of flow.
3. Carefully empty the water from the box into a sink, and begin Setup C.
- The food color is come to the center and make a circle look like a storm, and few minute later 3 spot of foodcorlor appear a little waterspouts.
Setup C
1. Set up the plastic box once again as in Setups A & B and fill with cold tap water to within 3-4 cm of the
top. Let the water become calm. Next, place two spots of food coloring near one end of the box. Position
one cup of hot water beneath each spot.
2. Use a plastic spoon to obtain a blue ice cube from your instructor. Carefully set the cube into the water
at the opposite end of the box from your dye spots. Use the spoon to steady the cube until it stops
moving.
3. Position yourself at eye level with the side of the box, and observe the water as the ice cube melts.
Sketch your observations in Diagram 3 below. Use arrows, once again, to indicate flow direction.
1. Set up the plastic box once again as in Setups A & B and fill with cold tap water to within 3-4 cm of the
top. Let the water become calm. Next, place two spots of food coloring near one end of the box. Position
one cup of hot water beneath each spot.
2. Use a plastic spoon to obtain a blue ice cube from your instructor. Carefully set the cube into the water
at the opposite end of the box from your dye spots. Use the spoon to steady the cube until it stops
moving.
3. Position yourself at eye level with the side of the box, and observe the water as the ice cube melts.
Sketch your observations in Diagram 3 below. Use arrows, once again, to indicate flow direction.
- The red food color is rise, the blue is sink. Because blue ice cube is more dense; red color less dense.
Follow- Up Questions
1. During the lab, what effect did the cups of hotwater have on the density of the water directly above them?
Less dense
2. What happened as result of this change?
4. You may have noticed convection cells in a pot of boiling macaroni. Put arrows on the dashed lines in
Figure 4 to show the direction of the flow in the pot. The hottest part of the burner is beneath the center
of the pot.
1. During the lab, what effect did the cups of hotwater have on the density of the water directly above them?
Less dense
2. What happened as result of this change?
4. You may have noticed convection cells in a pot of boiling macaroni. Put arrows on the dashed lines in
Figure 4 to show the direction of the flow in the pot. The hottest part of the burner is beneath the center
of the pot.
5. What situation would result in a decrease in atmospheric pressure at the earth' surface?
Air get hot and begin to rise
7. Above which are would the air become hotter in the afternoon?
A retaining pond next to the parking lot
8. Above which are would you find thee lowest air pressure?
The Retaining pond and the forest
9.Based on this arrangement, would you expect a breeze a blow toward the parking lot, or away from it ? Why?
Parking lot
10. From your knowledge of onshore and offshore breezes, explain why the wind would blow in from the sea toward the land during the afternoon.
Land heats faster than water because water has a higher specific heat (takes more energy to heat water than land). Because the ground is warmer over land, the air is warmer over the land, low pressure develops over land (higher temperature, air molecules spread out). The water is cooler so the air above the water is cooler allowing for an area of high pressure to develop over water (cooler temperature, air molecues are closer together).
11. A " monsoon effect" may happen in the summer as air over a continent becomes much warmer than air over the ocean.
A) As air over the continent become hotter, it will begin to rise
B) This cause lower pressure over the continent.
C) The flow of air will be toward the center of the continent.
12. Think globally now. Which region in our atmosphere is heated most intensely by the sun?
The equatorial region
13. As air the equator rise, does this become an are higher or lower pressure?
Lower pressure
14. What moves in to replace the rising air ?
Cool air
15. Number the following stages of circulation in the order in which thay are most likely to occur.
- Uneven heating
- Convection ( air rise)
- are of low pressure develops
- Wind( movement of air)
Air get hot and begin to rise
7. Above which are would the air become hotter in the afternoon?
A retaining pond next to the parking lot
8. Above which are would you find thee lowest air pressure?
The Retaining pond and the forest
9.Based on this arrangement, would you expect a breeze a blow toward the parking lot, or away from it ? Why?
Parking lot
10. From your knowledge of onshore and offshore breezes, explain why the wind would blow in from the sea toward the land during the afternoon.
Land heats faster than water because water has a higher specific heat (takes more energy to heat water than land). Because the ground is warmer over land, the air is warmer over the land, low pressure develops over land (higher temperature, air molecules spread out). The water is cooler so the air above the water is cooler allowing for an area of high pressure to develop over water (cooler temperature, air molecues are closer together).
11. A " monsoon effect" may happen in the summer as air over a continent becomes much warmer than air over the ocean.
A) As air over the continent become hotter, it will begin to rise
B) This cause lower pressure over the continent.
C) The flow of air will be toward the center of the continent.
12. Think globally now. Which region in our atmosphere is heated most intensely by the sun?
The equatorial region
13. As air the equator rise, does this become an are higher or lower pressure?
Lower pressure
14. What moves in to replace the rising air ?
Cool air
15. Number the following stages of circulation in the order in which thay are most likely to occur.
- Uneven heating
- Convection ( air rise)
- are of low pressure develops
- Wind( movement of air)