ENVIRONMENTAL EARTH SCIENCE
Energy Transfer in the Atmosphere
Name: ______________________________Per: _______Date:_____________
OBJECTIVES 1. Describe or diagram how energy from the sun heats the Earth. 2. Describe the radiation, conduction and convection of heat in terms of molecular movement.
INSTRUCTIONS: Read through this handout with a partner and follow the instructions and answer the questions together.
1. Light from the sun passes through the atmosphere with little or no heating of the air. We can tell this is true because when light from the sun shines in a window, the air does not feel immediately warmer in the sunbeam, but the floor warms up where sun hits it. Try this: Feel the temperature of the air in front of a desk lamp. Does each side of your hand feel equally warm? Why would one side of your hand feel cooler if the air was being heated by the light?
2. Is the side of your hand toward the light warmer? Why is there a difference? How could you get an accurate measure of the temperature of the air with a thermometer if the light can heat up the thermometer bulb? .
3. Explain your observations in terms of heating of air by visible light:
Heat and temperature do not mean the same thing. We will define heat as the overall motion of molecules, temperature as a measurement of the speed of molecules.
Here is an analogy to try to illustrate the difference between heat and temperature: Its 3:00 AM. You are near the highway in downtown Hartford. I have no idea why you are there, but suddenly a car goes down the highway at 85 mph, then a police car also going 85 mph. Note these cars are moving fast, but they are only the only cars on the highway. Now we return to, the same place, but at 4:30 PM rush hour. There are lots of cars now, but they are barely going 40 mph. In one case the cars are moving very fast, but there is not a whole lot of total motion. In the other case the speed is low, but overall motion is high - there's a lot of moving metal (and fiberglass, plastic, all that stuff). What does this have to do with heat and temperature and the atmosphere? The cars are molecules of air, their speed is their temperature, the total motion is the amount of heat/energy in the air.
4. Draw a diagram to illustrate this analogy:
5. Compare in your mind a cup of coffee at 99 C with a full a bathtub at 45 C. If both were left to cool down to room temperature, which would heat up the bathroom more?
6. Which took more energy to heat up, and so contains more heat?
7. Describe why global warming of only a few degrees represents an enormous increase in the heat energy in the atmosphere. (Answer here)
8. Heat transfer: heat is transferred to atmosphere in several ways: RADIATION: movement of energy by EM waves - this is the only heat transfer method that does not need molecules. DEMO: rub hands then radiate the heat of your hands toward another student's face. Diagram this.
9. Draw a diagram showing light traveling through air to Earths surface, warming the warming the surface, with radiation escaping back toward space as infrared heat.
10. CONDUCTION is the transfer of heat from contact between molecules. In the diagram above, faster molecules of the warm surface hit air molecules, knock them away faster than they were before, and the surface molecules now going slower. (An analogy for conduction is to roll a ball into another one. How does the motion of each ball change?
11. In terms of conduction and molecular motion, describe why the windows of the classroom feel cold: (answer here)
12. CONVECTION is heat transfer by moving fluid (a fluid is anything that flows - air or water). A convection current is the movement of a fluid because of a difference in density, usually caused by a a difference in temperature. EXAMPLE: Look closely at a chimney. The gases from the chimney rise because they are warmer than the air around them. This a convection current. Diagram warm air rising straight up over a warm spot on Earth's surface - where must air come from in order to repplace the air that rises? (answer here)
13. What areas of the planet will produce rising air that transfers heat upward in the atmosphere?
Heat Stations
Visit each station in the room and write what is asked for below
1. Conduction: Write and diagram what you would put on the backdrop for a 5th grade science fair that explains how the two sets of ball bearings and the animation demonstrate heat transfer by conduction.
2. The Heat Box: Diagram the box and write on your diagram signs to explain how energy is being transferred.
3. Molecules: The models represent the most abundant molecules that make up our air. Put them into 2 groups: the 2-atom molecules and the 3 or more atom molecules. Draw each type in their groups and label them with element names from the key. In this set of molecules, the 2-atom ones are the most abundant in the atmosphere. The molecules in this set with 3 or more atoms absorb infrared radiation and are called greenhouse gases. Put these labels on your groups.
4. Radiation animation. List how each frame of the movie should be labeled.
5. Heat of ice molecules: make a sign that explains how this animation shows heat and how that is different from temperature.
6. Change of state (solid, liquid, gas): make a sign that explains how these 3 animations show what happens to the molecules of ice when enough heat is absorbed to melt the ice, then to evaporate it.