Lab Activity: Earth's Energy Budget and the Greenhouse Effect
This activity was selected for the On the Cutting Edge Reviewed Teaching Collection
This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: Jun 30, 2009
In a previous lab activity, students examine the global, long-term average energy budgets for the earth's surface and atmosphere, accounting for radiative energy as well as other forms of energy. (The numbers come from a textbook.) In the current lab, students:
- investigate how those numbers compare to observations in global data sets of temperature, solar and longwave infrared radiative fluxes, albedo, and other quantities, which students display and analyze using "My World GIS" software;
- investigate spatial and seasonal variability in several aspects of these budgets;
- investigate possible connections between some of these variations and properties of the earth; and
- compare the observations to theoretical calculations based on the Stefan-Boltzmann relation.
- Extend previous knowledge about several aspects of the earth's global average surface, atmospheric, and whole-earth energy budgets, to consider spatial and temporal variability.
- Connections between spatial variations in the energy budget and properties of the earth, such as albedo, vegetative cover, rainfall distribution, distribution of water vapor, and topography.
We haven't formulated formal science process objectives for this activity, but if we did, they might look like this:
- Use GIS software (a tool used by some climate scientists) to display, describe, analyze, and interpret global observational data sets of climate-related quantities.
- Become aware of the nature of observed data, including its nature, source, limitations, accuracy, and completeness (or lack thereof).
- Pose hypotheses to account for patterns in the observations, and test those hypotheses using other data sets.
- Compare theoretical calculations and results of data analysis to previously published results about the earth's global energy budget.
Context for Use
The activity is the 6th in a sequence of lab activities designed to build understanding of the earth's energy budget, including the greenhouse effect.
As designed, this activity requires access to computers equipped with "My World GIS" software and appropriate global data sets. Students should already have some facility with the software as well as knowledge about radiative energy, the Stefan-Boltzmann law, the earth's long-term, global average energy budget, and the seasons, all acquired during previous lab activities and supporting instructional activities.
For the purpose of this submission, I regard the style of this activity is more important than the particular content and prerequisites. Several previous lab activities are similar in style but have less prerequisite skill and knowledge.
It would be possible to adapt at least some of this lab to a context without computers and software, by providing students with hard copies of the data displays that this lab asks students to construct using My World GIS software. (They would then not get experience using a tool of the sort that some climate scientists use in their work to explore data, but that is only one of several science process goals of this activity and arguably not the most important one. The activity could be completed a lot faster that way, too. I don't know what impact this might have on student understanding of the concepts--it could be positive because they don't have to struggle with the software to display the data, but they don't have "ownership" of the displays nor do they engage as deeply with the data--for example, they wouldn't be required to figure out whether the displays they've generated have problems or not, which would be an experience that could be good for them.)
Description and Teaching Materials
The lab activity itself is available here.
The file contains hypertext links to prerequisite lab activities and a couple of supporting animations. Upon request, I (dempsey AT sfsu.edu) can provide digital versions of the data displays that students are asked to create as part of the lab activity using the My World GIS software.
Lab Activity #6: Earth's Energy Budget and the Greenhouse Effect (HTML File 14kB Jun30 09)
Teaching Notes and Tips
There are, of course, costs associated with the prospective benefits. Most notably, this approach can take a lot of class time. This comes partly from the need for students to learn to use the software. We devote one lab activity (part of one 3-hour class period) at the beginning of the semester to this purpose, and, to help justify the necessary time investment, we use the software for several subsequent lab activities, culminating in the one described here. Students support each other as they continue learning the software in subsequent labs, and whenever possible we provide step-by-step written instructions about what to do. These instructions can be relatively lengthy, and students can become so focused on carrying out the steps that they lose track of the lab objectives (including those for both content and science process). Hence, it's important to get their attention periodically to focus on the questions posed by the lab activity. We do this both via interactions with individual and small groups of students and via intermittent whole-class discussions.
My World GIS does not come with all of the data sets required by this lab activity and several of its prerequisite labs. (We developed these activities for use with My World GIS's predecessor, "Worldwatcher", which does have the data sets.) Hence, we've had to add the necessary data sets to the My World GIS configuration, which means that My World GIS can't be used "out of the box" to carry out this lab. (For access to these data sets, see "Resources" below.)
This lab activity, like several of its prerequisite lab activities, asks students to interpret patterns in the data that they display and analyze. Because the data sets are real, they sometimes contain irregularities and missing data. It's important to make students aware of these and other limitations of (the) data and take them into account when posing and testing hypotheses about the data. (Bad or missing data can sometimes explain observed features in data.)
An in-class quiz within a week or two asks about the main points made by the lab activity. However, in practice we have focused these quizzes on conceptual understanding of subject matter rather than science process. There's no reason why quiz questions about science process couldn't be posed, however.
References and Resources
We use several global observational data sets that come with software called "Worldwatcher", which is the predecessor to My World GIS. (The lab activity originally used Worldwatcher.)
(Contact me at dempsey AT sfsu.edu for instructions about how to install the data sets.)