MODELING HEATING OF THE EARTH What Makes You Hot?

Transcription

1 MODELING HEATING OF THE EARTH What Makes You Hot? Created in the Making Global Local workshops University of Colorado at Boulder Summer, Created by: Grant Euler, Physics and Environmental Sciences, Arvada High School Brian Huang, Physics, Centaurus High School Joanna Griego, Biology and Chemistry, Trinidad High School

2 MODELING HEATING OF THE EARTH What makes you hot? Created in the Making Global Local workshops University of Colorado at Boulder Driving Question What makes you hot? Grade Level Grades 9-12 Lesson Time Requirement Four- five 50- minute class periods in a regular Physics curriculum (2 ½ days for IB curriculum) Climate Literacy Principles Addressed (links) 1. The Sun is the primary source of energy for Earth's climate system. 2. Climate is regulated by complex interactions among components of the Earth system. Colorado State Standards Addressed (links) High School: Physical Science Apply an understanding that energy exists in various forms, and its transforma- tion and conservation occur in processes that are predictable and measurable High School: Earth Science Evaluate evidence that Earth s geosphere, atmosphere, hydrosphere, and bio- sphere interact as a complex system Learning Objectives Students will be able to manipulate different variables in the model and use this to make infer- ences about the temperature of Earth 2

3 Prior Knowledge Required Students should know and understand the origins of the Celcius and Fahrenheit temperature scales, thermal equilibrium, heat capacity, energy conservation, blackbody radiation, Wein s Law and how to use Excel. Common Student Misconceptions & Prior Understandings o o o 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. Correction: All objects absorb and reflect light to different degrees. Our ability to see ob- jects depends on the reflection of light. Misconception: The earth gets heat from the sun. Correction: 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. Correction: Without the greenhouse effect, the earth would not be warm enough to sup- port life. The increase in temperature due to increased greenhouse gases in the atmosphere will have negative effects. Materials Computers with Excel Internet access, or pre- downloaded and installed PhET simulation, Blackbody Spectrum, at spectrum Introduction to Lesson In an effort to understand past, present, and possible future climates, scientists enter atmos- pheric observations into computer programs that help them create models of Earth s atmos- phere and climate. Using Excel, students will manipulate different variables in a simple mathe- matical model and use this model to make inferences about the temperature of Earth. Lesson Sequence 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 ( spectrum) and develop questions you would like to explore in class. Day 2: PhET Simulation

4 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) Ex- cel 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. Student Handouts All available at LearnMoreAboutClimate.Colorado.edu under For Educators. 1. Part A. PhET Blackbody Radiation Simulation at spectrum. This may be used on- line, or downloaded and installed 2. Part B. Pre- Lab Questions 3. Part C. Excel Model 4. Part D. Homework assignment Assessment Students will create a set of graphs that depict 3 different variables. Each graph will be accom- panied 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 4

5 Understanding Student Misconceptions about Weather and Climate onal&columnid=professional!misconceptions Current Concentrations of Greenhouse Gasses (and Increased radiative forcing) A Climate Modeling Primer Example Homework from ATOC 1060 Wikipedia Entry on Temperature Calc of Earth Boltzmann_law#Temperature_of_the_Earth The Carbon Dioxide Greenhouse Effect Climate Prediction Models - example lesson plans and excel sheet physics Real Climate - Learning from a Simple Model from- a- simple- model/ Wolfram Alpha Educational Brief - Solar Radiation and the Earth System briefs/ed- stickler/ed- irradiance.html Brookhaven Laboratory - Heat Capacity, Time Constant, And Sentivity OF EARTH'S CLIMATE SYSTEM References See resources and background reading above. Extensions 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.

6 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 sys- tem. 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 6