Climate Change
Earth and Space Science
MS
Energy Balance and Atmosphere
Greenhouse Effect in a Greenhouse
Radiant Energy
Urban Heat Island
It works well to have middle school students work in pairs to help them run the models/temperature sensors and record data and analyze/communicate results. It will be important for students to know how to run the models and temperature sensors, including each of the model/graphing features and how they are activated or modified.
In the activity "Urban Heat Island" you are asked to take the students outside to collect data. To limit the number of computers going outside consider having larger groups do the data collecting for various surfaces and then using a projection system to share that collected data. Another alternative is if you have handheld devices (i.e. LabQuest II) you could have students collect the data with these devices and display them using a projection unit.
For the "Greenhouse Effect in a Greenhouse" and "Urban Heat Island" activities it is important to discuss sun eye safety.
For the Greenhouse Effect in a Greenhouse activity it is important to discuss the importance of being careful when punching a hole in the plastic food container.
For the Urban Heat Island activity it is important to review how to use a hammer and discuss the importance of not polluting the environment, specifically by not leaving items in the trees.
Make sure that students understand how to run the model in the Energy Balance and Atmosphere and Radiant Energy activities, including all of its features and how they can be modified. It is helpful to have students run the model in Collect Data I in the Energy Balance and Atmosphere activity and then to address questions during/after running it for a few trials based upon student performance. It is also important that students understand how to take snapshots of the model so they can analyze the data effectively.
Also make sure that students know how to run the temperature sensors and graphs to collect temperature data in the Greenhouse Effect in a Greenhouse and Urban Heat Island activities.
For the Greenhouse Effect in a Greenhouse the following materials are needed per group:
For the Urban Heat Island the following materials are needed per group:
This activity call for having students take measurement outside the classroom so think about how you want to manage the technology. Maybe limiting the number of computers going outside and using a projection unit to display data.
Each activity will take two days in this unit to allow time for effective data collection and analysis. Then one day should be used for conclusions through group discussion presentations and whole class wrap-up.
This unit investigates the earth science concepts related to Earth's atmosphere, the factors that affect it, and energy transfer. The activities specifically investigate the affect of the atmosphere on Earth's energy balance and temperature when sunlight strikes earth, the greenhouse effect, and how to lessen a heat island effect in a city. The following are the big ideas that pertain to this set of activities:
The activities are motivated by the discovery questions:
In this unit you will examine how earth's systems interact and the human impacts on the them, specifically the atmosphere.
What is the earth made up of?
The earth is mostly rock (the geosphere/lithosphere). Three-fourths of the earth's surface is covered by a layer of water (the hydrosphere), some of it frozen (the cryosphere), and the entire planet is surrounded by a layer of air (the atmosphere).
What is the atmosphere made up of?
The atmosphere is a mixture of nitrogen, oxygen, and trace amounts of water vapor, carbon dioxide, and other gases.
What is the major source of energy for changes on earth's surface and what type of energy does it give off?
The sun is the major source of energy and it gives off solar radiation.
How is thermal energy transferred?
Thermal (heat) energy is transferred through a material by the collisions of atoms within the material.
What are infrared rays?
Infrared light lies between the visible and microwave portions of the electromagnetic spectrum. "Near infrared" light is closest in wavelength to visible light and "far infrared" is closer to the microwave region of the electromagnetic spectrum. Far infrared waves are thermal. We experience this type of infrared radiation every day in the form of heat! The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared. Shorter, near infrared waves are not hot at all - in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV's remote control. The primary source of infrared radiation is heat or thermal radiation, any object which has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. For example, hot charcoal may not give off light but it does emit infrared radiation which we feel as heat. The warmer the object, the more infrared radiation it emits.(http://science.hq.nasa.gov/kids/imagers/ems/infrared.html)
What are the greenhouse gases?
Any gas that absorbs infrared radiation in the atmosphere is a greenhouse gas. Greenhouse gases include, carbon dioxide, methane, and water vapor.
If you continued to collect data with the cover on would the temperature continue to rise?
The temperature would continue to rise, though the rate of change may slow down.
What is "albedo"?
"Albedo" or reflectivity is the the ratio of the amount of light reflected from a material to the amount of light shone on the material. You will change the ratio in the model's albedo slider.
Think about the idea of albedo we investigated in the activity of Radiant Energy. Is the albedo of the grassy surface higher or lower than a cement surface? How might this explain the temperature differences?
The albedo of the grassy area would be less than the cement surfaces. This would mean that more heat is being absorbed by the grassy area which would tend to cool the air above.
Based on what you have learned in this unit what are the some of the causes of global climate change?
To change climate globally, either the amount of heat that is let into the system changes, or the amount of heat that is let out of the system changes. Global climate change can occur from natural factors (changes in the sun's intensity, etc.), natural processes within the climate system (changes in ocean circulation, etc.), or human activities that change the atmosphere's composition (burning fossil fuels, etc.). Most climate scientists agree, based on data trends, that human activities are the primary variable causing global climate change through greenhouse gas emissions. These human activities include burning of fossil fuels for energy, deforestation, land use changes, and waste management/agricultural practices that release methane and nitrous oxide. Due to these activities, greenhouse gases (water vapor, carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons) are increasing, trapping heat in the lower atmosphere due to the greenhouse effect, resulting in global climate change.
What do you think are some factors that affect your community's human impact on global climate change?
Answers will vary based upon your community. An example answer is one activity in my community that is causing climate change is urbanization. I live in a city that is the largest growing in Iowa. My school district is about 12 miles away from this city, meaning that they are also experiencing lots of home and business construction. All of this building leads to increased burning of fossil fuels and deforestation. Commuting to Des Moines also leads to increased carbon emissions. My school district is also primarily rural in another area, leading to deforestation and waste management concerns due to large-scale farming.
What are some things in our community that might indicate that climate change in happening?
Answers will vary. An example answer is the effects of global climate change are evident locally based on data trends. There are higher temperatures during the summer and winter and precipitation is above average. More floods are occurring based on heavy downpours being twice as frequent from a century ago and the floods of 2008. Managing crops and livestock is challenging due to the drought conditions, even though the growing season has been extended.
If large cities wanted to reduce the effects of their heat island impact what could they do?
Answers may vary. Possible ideas would be to increase green spaces by planting roof top gardens or parks, keeping green spaces, changing building materials that would reflect less heat energy, etc.
The atmosphere is a mixture of nitrogen, oxygen, and trace amounts of water vapor, carbon dioxide, and other gases.
Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming have changed the earth's systems (biosphere, geosphere, hydrosphere, and atmosphere). Processes that take place on the surface of the earth influence the composition and temperature of the atmosphere.
Human activities, such as the release of greenhouse gases from burning fossil fuels, are major factors in the current rise in Earth's mean surface temperature (global warming). Reducing the level of climate change and reducing human vulnerability to whatever climate changes do occur depend on the understanding of climate science, engineering capabilities, and other kinds of knowledge, such as understanding of human behavior and on applying that knowledge wisely in decisions and activities.
Energy appears in different forms and can be transformed within a system.
Light and other electromagnetic waves can warm objects. How much of an object's temperature increases depends on how intense the light striking the surface is, how long the light shines on the object, and how much of the light is absorbed.
Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection).
The sun is a major source of energy for changes on the earth's surface. The sun loses energy by emitting light. A tiny fraction of that light reaches the earth, transferring energy from the sun to the earth. The sun's energy arrives as light with a range of wavelengths, consisting of visible light, infrared, and ultraviolet radiation.
Infrared light lies between the visible and microwave portions of the electromagnetic spectrum. "Near infrared" light is closest in wavelength to visible light and "far infrared" is closer to the microwave region of the electromagnetic spectrum. Far infrared waves are thermal. We experience this type of infrared radiation every day in the form of heat! The heat that we feel from sunlight, a fire, a radiator or a warm sidewalk is infrared. Shorter, near infrared waves are not hot at all - in fact you cannot even feel them. These shorter wavelengths are the ones used by your TV's remote control. The primary source of infrared radiation is heat or thermal radiation, any object which has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. For example, hot charcoal may not give off light but it does emit infrared radiation which we feel as heat. The warmer the object, the more infrared radiation it emits." (http://science.hq.nasa.gov/kids/imagers/ems/infrared.html)
Any gas that absorbs infrared radiation in the atmosphere is a greenhouse gas. Greenhouse gases include, carbon dioxide, methane, and water vapor. (http://www.epa.gov/climatechange/glossary.html)
"Albedo" or reflectivity is the the ratio of the amount of light reflected from a material to the amount of light shone on the material. Absorbed sunlight is converted into thermal energy to make a material hotter.
Based on this model, would increased cloud cover raise or lower the Earth's net energy gain and its temperature? Explain.
Increased cloud cover would lower the Earth's net energy gain and temperature because if skies are cloudy, some of the sun's rays are reflected off the clouds back into space. Therefore, less of the sun's energy is able to reach the earth's surface, which causes the earth to heat up more slowly. This leads to cooler temperatures.
Based on this model, would increased levels of greenhouse gases in the atmosphere raise or lower Earth's temperature? Explain.
Increased levels of greenhouse gases would raise Earth's temperature because the greenhouse gas molecules absorb/trap heat.
Make a list of the sources of greenhouse gases in the atmosphere. Note which sources are natural and which are the result of human activities.
The primary and natural greenhouse gases in the atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Human activities can increase all of these gases. Greenhouse gases that are not naturally occurring and the result of human activities include byproducts of foam production, refrigeration, and air conditioning called chlorofluorocarbons (CFCs), as well as hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) generated by industrial processes.
Make a list of the ways that greenhouse gases are removed from the atmosphere. You may need to do some research and have a class discussion about this. It is a very complicated process!
They are removed when it is absorbed by plants as part of the carbon cycle.
Make a list of what changes in Earth's climate might change the amount of cloud cover. Explain how cloud cover would be affected by each change.
If Earth's climate warms due to the greenhouse effect, the weather patterns and the associated clouds would change. It's not yet clearly known whether global warming will decrease cloud cover, which would effectively speed up the process of climate change, or increase cloud cover, which would slow it down.
Why did the plastic cover cause a change in temperature, if any?
The plastic cover trapped thermal energy in, raising the temperature, because of absorbed infrared radiation.
How is this situation like the atmospheric "greenhouse effect"? How is it different?
The Earth gets energy from the sun in the form of sunlight. The Earth's surface absorbs some of this energy and heats up. The Earth cools down by giving off a different form of energy, called infrared radiation. Before all this radiation can escape to outer space, greenhouse gases in the atmosphere absorb some of it, which makes the atmosphere warmer. As the atmosphere gets warmer, it makes the Earth's surface warmer, too. The plastic serves as the atmosphere in this activity.
Was the temperature change different for light sand or sugar compared to dirt? Why?
The temperature change was less for light sand and sugar due to less absorption of infrared radiation and more reflectivity of the lighter colored objects.
What was the result of using white paper instead of dirt or sand? Why did this result occur?
The temperature change decreased more with white paper because it had more reflectivity and was less compact.
Is there any evidence that dirt and sugar "hold the heat" better than paper? What is the evidence?
Yes, the temperatures were hotter and more stable.
What happens to sun rays that enter the model?
The rays are absorbed in earth's surface as thermal energy and then reflected as infrared rays, or immediately reflected back into outer space.
Where do infrared rays come from, and where do they go?
The primary source of infrared radiation is heat or thermal radiation, any object which has a temperature radiates in the infrared. When an object is not quite hot enough to radiate visible light, it will emit most of its energy in the infrared. The warmer the object, the more infrared radiation it emits. They are eventually reflected back into outer space.
How does the "albedo" slider change the model?
The greater the albedo ratio the less energy that is absorbed in earth's surface.
Which would make Earth hotter, on average? a) higher albedo b) lower albedo Explain.
A lower albedo would make the earth hotter due to less reflectivity.
What change might raise or lower Earth's albedo? Why would this change affect the albedo?
Human interactions might raise or lower the Earth's albedo. For example, burning wood and fossil fuels adds black carbon to the atmosphere. Some black carbon settles on the surface of the ice, which reduces albedo.
Sunlight is always arriving on Earth. Why doesn't Earth continually get hotter?
The Earth doesn't continually get hotter because it has an atmosphere and most sunlight is reflected back into space (from clouds, landforms, etc.)
Based on your data, what type of changes or additions to parking lots or rooftops could help to reduce the urban heat island effect?
Parking lots can be created with existing paving technologies (such as asphalt and concrete) as well as newer approaches such as the use of coatings or grass paving. Green roofs, or rooftop gardens, could be built on rooftops to provide shade and remove heat from the air.
Is there a relationship between the air temperature and the color of the surface below it? Would more reflective colors on surfaces of roads or rooftops change the temperature of the surrounding air? Explain.
Yes, air temperature is greater when the color of the surface below it is darker because more heat is absorbed. More reflective colors on the surfaces of roads or rooftops would change the temperature of the surrounding air because less heat would be absorbed and transmitted due to reflectivity.
How do you think the temperatures at night are different in areas with different types of surfaces? Explain your reasoning.
In the evening, the difference in temperature is higher because of the slow release of heat from urban infrastructure. "As urban areas develop, changes occur in their landscape. Buildings, roads, and other infrastructure replace open land and vegetation. Surfaces that were once permeable and moist become impermeable and dry. These changes cause urban regions to become warmer than their rural surroundings." (http://www.epa.gov/heatisld/about/index.htm)
If roads and rooftops were painted white, would that reduce the heat island effect? Why?
Yes, because the albedo on the surfaces would be increased.
Why is the air temperature lower in areas with plants and trees?
Trees and vegetation lower surface and air temperatures by providing shade and through evapotranspiration (evaporation and transpiration working together to lower temperatures by using heat from the air to evaporate water).
To help students further analyze the causes and effects of global climate change as well as what they can do to balance earth's temperature they could research the following guided questions surrounding their own community and build discovery questions of their own.