MODELING HEATING OF THE EARTH
What Makes You Hot?
Created in the Making Global Local workshops, University of Colorado at Boulder
The driving question for the climate modeling lesson is "What makes you hot?" The amount of solar energy absorbed or radiated by Earth is modulated by the atmosphere and depends on its composition. Greenhouse gases - such as water vapor, carbon dioxide, and methane - occur naturally in small amounts and absorb and release heat energy more efficiently than abundant atmospheric gases like nitrogen and oxygen. Small increases in carbon dioxide concentration have a large effect on the climate system. The interconnectedness of Earth's systems means that a significant change in any one component of the climate system can influence the equilibrium of the entire Earth system. Students will be able to manipulate different variables in the lesson's model and use this to make inferences about the temperature of Earth. This model lesson is designed for 9th - 12th grade students.
What makes you hot?
Lesson Time Requirement
Four-five 50-minute class periods in a regular Physics currriculum (2 1/2 days for IB curriculum)
Climate Literacy Principles Addressed
- The Sun is the prmary source of energy for Earth's climate system
- Climate is regulated by complex interactions among components of the Earth system
Colorado State Standards Addressed
- High School: PS5, PS6, ES4
- Students will be able to manipulate different variables in the model and use this to make inferences about the temperature of the Earth.
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What Makes You Hot?
Common student misconceptions and prior understandings:
Misconception: Light can only be reflected from shiny surfaces (such as a mirror). Students may also believe that an object cannot absorb and reflect light - it must do one or the other. *All objects absorb and reflect light to different degrees. Our ability to see objects depends on the reflection of light*
Misconception: The earth gets heat from the sun. *The sun is actually too far from the earth to heat it directly. Instead, the light from the sun is reflected or absorbed by objects on earth. Absorbed light usually increases the energy in an object, causing the object to heat up.*
Misconception: The greenhouse effect is bad and will eventually cause all living things to die. *Without the greenhouse effect, the earth would not be warm enough to support life. The increase in temperature due to increased greenhouse gases in the atmosphere will have negative effects.*
Computers with Excel
Internet access, or pre-downloaded and installed PhET simulation, Blackbody Spectrum, at http://phet.colorado.edu/en/simulation/blackbody-spectrum
Day 1: Direct instruction on blackbody radiation and calculate the blackbody radiation of an ob-ject at a certain temperature with the class. Homework – play with Blackbody Spectrum Simulation in PhET (http://phet.colorado.edu/en/simulation/blackbody-spectrum) and develop questions you would like to explore in class.
Day 2: PhET Simulation Homework: Use textbook and the internet to answer the (A) Pre-Lab questions (see Handouts, below)
Day 3: Finish Pre-lab questions, go over answers in class discussion. Begin working with (C) Excel Model (see Handouts, below).
Day 4: Continue to manipulate the model and determine which factors have an effect on the temperature of the Earth. Create and describe graphs for assessment
Day 5: Review Lab. Complete a free-writing exercise on what a climate model looks like and how their perspective of models has changed.
- Part A. PhET Blackbody Radiation Simulation at http://phet.colorado.edu/en/simulation/blackbody-spectrum. This may be used on-line, or downloaded and installed
- Part B. Pre-Lab Questions
- Part C. Excel Model
- Part D. Homework assignment
Students will create a set of graphs that depict 3 different variables. Each graph will be accompanied by a descriptive paragraph or two describing how variables within the model were ma-nipulated to get the results. Students will also write an analysis of scientific models and how their perspectives of models has changed by this activity.
Lesson Development Prompts
This lesson was developed for high school physics courses and designed to be taught during a unit on heat and thermodynamics. It provides students the opportunity to examine and work with a computer model. This lesson integrates inquiry strategies in that students develop their own questions and use the PhET Blackbody simulation to investigate Blackbody radiation. They also have the opportunity to investigate how different variables affect the heating of the earth, primarily, how the sun is the source of most of Earth’s heat and how changing characteristics of solar output, distance, earth’s surface, and the composition of the atmosphere can change Earth’s climate.
Background Reading for Students and/or Teachers
- Understanding Student Misconceptions about Weather and Climate http://beyondpenguins.nsdl.org/issue/column.php?date=June2008&departmentid=professional&columnid=professional!misconceptions
- Current Concentrations of Greenhouse Gasses (and Increased radiative forcing) http://cdiac.ornl.gov/pns/current_ghg.html
- A Climate Modeling Primer http://www.climatemodellingprimer.net/
- Example Homework from ATOC 1060
- Wikipedia Entry on Temperature Calc of Earth http://en.wikipedia.org/wiki/Stefan–Boltzmann_law#Temperature_of_the_Earth
- The Carbon Dioxide Greenhouse Effect http://www.aip.org/history/climate/co2.htm
- Climate Prediction Models - example lesson plans and excel sheet http://www.climateprediction.net/content/level-physics
- Real Climate - Learning from a Simple Model http://www.realclimate.org/index.php/archives/2007/04/learning-from-a-simple-model/
- Wolfram Alpha http://www.wolframalpha.com/
- Educational Brief - Solar Radiation and the Earth System http://education.gsfc.nasa.gov/experimental/all98invproject.site/pages/science-briefs/ed-stickler/ed-irradiance.html
- Brookhaven Laboratory - Heat Capacity, Time Constant, And Sentivity OF EARTH'S CLIMATE SYSTEM http://www.ecd.bnl.gov/steve/pubs/HeatCapacity.pdf
See resources and background reading above
This lesson was designed for Junior and/or Senior level physics students. It could be used in Freshman level Earth Science but would require more time.
Students could apply the model to other planets.
Climate Literacy Essential Principles Addressed
The Sun is the primary source of energy for Earth's climate system.
- a. Sunlight reaching the Earth can heat the land, ocean, and atmosphere. Some of that sunlight is reflected back to space by the surface, clouds, or ice. Much of the sunlight that reaches Earth is absorbed and warms the planet.
- b. When Earth emits the same amount of energy as it absorbs, its energy budget is in balance, and its average temperature remains stable.
- e. A significant increase or decrease in the Sun's energy output would cause Earth to warm or cool. Satellite measurements taken over the past 30 years show that the Sun's energy output has changed only slightly and in both directions. These changes in the Sun's energy are thought to be too small to be the cause of the recent warming ob-served on Earth.
Climate is regulated by complex interactions among components of the Earth system
- a. Earth's climate is influenced by interactions involving the Sun, ocean, atmosphere, clouds, ice, land, and life. Climate varies by region as a result of local differences in these interactions.
- c. The amount of solar energy absorbed or radiated by Earth is modulated by the at-mosphere and depends on its composition. Greenhouse gases— such as water vapor, carbon dioxide, and methane— occur naturally in small amounts and absorb and release heat energy more efficiently than abundant atmospheric gases like nitrogen and oxygen. Small increases in carbon dioxide concentration have a large effect on the climate system.
Colorado State Science Standards
High School: Physical Science
Apply an understanding that energy exists in various forms, and its transformation and conser-vation occur in processes that are predictable and measurable.
- PS 5. Energy exists in many forms such as mechanical, chemical, electrical, radi-ant, thermal, and nuclear, that can be quantified and experimentally deter-mined.
- PS 6. When energy changes form, it is neither created not destroyed; however, because some is necessarily lost as heat, the amount of energy available to do work decreases.
High School: Earth Science
Evaluate evidence that Earth’s geosphere, atmosphere, hydrosphere, and biosphere interact as a complex system
- ES 4. Climate is the result of energy transfer among interactions of the atmos-phere, hydrosphere, geosphere, and biosphere
You may download a zip file including all lesson plan handouts and resources.