Thermodynamics: Sea ice melt

Steven Neshyba, University of Puget Sound; and Penny Rowe, NorthWest Research Associates
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Summary

Students learn about thermodynamics topics through calculation of the amount of heat required to melt Arctic sea ice. They start by watching an online animation of changing polar ice with time. They next download data of Arctic ice extent and volume. Working in a Jupyter Notebook, they use thermodynamic principles and equations to plot the phase diagram of water, find the freezing point depression of Arctic sea ice in equilibrium with sea water, and compute the change in the enthalpy of fusion of water resulting from that temperature depression.

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Learning Goals

Students become familiar with Arctic sea ice, including its seasonal cycle and loss of ice with climate change. They download and analyze Arctic sea ice and apply thermodynamic principles to predict the heat required to melt it. This analysis is scaffolded by a Computational Guided Inquiry (CGI) module, which for this activity takes the form of a set of Jupyter Notebooks, which they use to conduct inquiry in the role of a scientist through making calculations and producing and examining plots. Critical thinking and active inquiry is promoted by open-ended responses to prompts (Pause for Analysis questions). Specific learning goals are as follows:

  1. Learn about datasets available for Arctic sea ice volume and extent, and how Arctic sea ice is changing.
  2. Be familiar with calculating sea ice thickness from extent and volume.
  3. Develop skills in acquiring and plotting data using Python.
  4. Be able to construct a phase diagram of water and integrate the Clapeyron equation to get the Clausius-Clapeyron and Thomson Equations.
  5. Learn how to compute the heat required for seasonal melt of Arctic sea ice.
  6. Practice finding the freezing point of Arctic sea ice in equilibrium with sea water using Raoults' Law.
  7. Have experience correcting the change in the enthalpy of fusion of ice when it is in equilibrium with seawater, using Kirchoff's Equation.

Context for Use

This activity is designed to be used in a course such as in Physics or Physical Chemistry in which thermodynamic principles are taught. Students must have in-class access to computers with internet access and with Jupyter Notebook installed. A computer lab with pre-loaded software can be used or, as in successful pilots, students can download the software onto personal laptops before class (instructions are provided). Problems can be mitigated by having students work in pairs and having an extra laptop or two available as needed, equipped with the software. The activity has successfully been taught in both classes and lab sections of 20 students or less. Application in large classes can be fostered by additional support, if available; e.g. through teaching assistants. The activity typically takes 3 to 5 hours and includes homework assignments. No previous computational or coding experience is required. The instructor will give an introductory lecture to the thermodynamic concepts, assign pre-module homework, guide the students in working through the module, and facilitate group discussions. The module is adaptable – the three parts can be used in combination, or each as a standalone module (with slight modifications), as has been done in a lower-level Engineering Physics course.

Description and Teaching Materials

Overview

In this module, students will work actively with polar data through computer programming in Jupyter with Python. The instructions and notebook are designed so that no prior coding experience is necessary on the part of the student or instructor. This module is made up of three Jupyter Notebooks, which can be taught sequentially or divided between class periods. Preparation can take place in a block (a single preparation activity for all three modules), or prior to each module separately. The notebook and all other materials needed to implement the activity are provided below. Links to online resources used are provided and digital backups are included in case data is moved or removed. The following describes activities and the materials used for each.

What do the student modules look like? Take a quick look at how the modules look in Jupyter Notebook: Sea Ice Melt Module 1, Sea Ice Melt Module 2, Sea Ice Melt Module 3. (These are static images. For the interactive versions, see the instructions and materials below.)

Materials

  • Student setup guides (Zip Archive 1.2MB Apr29 20). After unzipping, this includes:
    • finding_moving_files_mac.docx, finding_moving_files_pc.docx: File management on your computer
    • installing_running_jupyter_mac.docx, installing_running_jupyter_pc.docx
    • Introduction_to_python3.ipynb: Python3 tutorial, to be run in Jupyter Notebook
  • Sea Ice Melt module (Zip Archive 21kB Apr28 20). After unzipping, this includes:
    • Sea_ice_melt_1_Introduction_to_polar_data.ipynb
    • Sea_ice_melt_2_Constructing_a_phase_diagram.ipynb
    • Sea_ice_melt_3_Effects_of_sea_water.ipynb
  • . After unzipping, this includes:
    • Sea_ice_melt_1_key.ipynb
    • Sea_ice_melt_2_key.ipynb
    • Sea_ice_melt_3_key.ipynb
  • Digital Backup: CO2 concentration (as of 2020 March) (Acrobat (PDF) 238kB Mar8 20)

Instructor Preparation

  1. Download materials above and unzip files.
  2. Follow the workflow below.
  3. Compare the completed notebooks to the provided keys and review the answers to questions and rubric in the Assessment materials.
  4. Modify the notebooks as desired and/or include only a portion of them.

Workflow

  1. The instructor provides the setup guides to the students.
  2. As a homework assignment, students follow the instructions for installing Jupyter Notebook on a Mac or PC. Alternatively, the instructor ensures the software is available in a computer lab that will be used. Students also work through the instructions for finding and moving files on a Mac or PC.
  3. The instructor provides the Seasonal Arctic Ice Melt module files to students. Students put all the files Seasonal Arctic Ice Melt module files together in a folder on their computer. (Note that *.ipynb files cannot be opened with the text editor; they must be saved to the computer and opened from Jupyter Notebook). Instructors typically make the files within available for the students on Google Drive or a platform used by their institution, and direct students to put the files into a directory on their computers.
  4. The instructor may choose to demonstrate any of the above task on an overhead display before or after the students attempt it as a homework assignment, or have the students follow along with the instructor in class.
  5. The instructor gives a lecture explaining that the class will now apply concepts of Thermodynamics to a real-world example (melting of Arctic sea ice), and introduces the concepts of sea ice volume and extent. The relevant material is provided in the introduction to the first notebook: Seasonal Arctic ice melt – 1. Introduction to polar data.
  6. Students work through Introduction_to_python3.ipynb (provided in step 3).
  7. Students watch a video about Arctic sea ice loss. The instructor may optionally have students watch other climate change videos (see references and resources below).
  8. Working at a computer singly or in pairs, students complete the student module, which is composed of three parts (each as a separate notebook). The instructor circulates around the class, helping as needed. The instructor may choose to have students complete all three notebooks in a long lab session, complete them sequentially in different classes.
  9. The instructor should bring students together at the end of each notebook and again after students complete all three notebooks, to meet as a group to discuss student responses to the Pause for Analysis questions as well as any observations or questions.
  10. The instructor wraps up the activity by linking the student work back to the original goals.

Teaching Notes and Tips

Digital Backups

Data archived online is sometimes moved or removed, or students may have difficult accessing it. In case of this possibility, we have included an image showing the CO2 concentration (as of 2020 March) (Acrobat (PDF) 238kB Mar8 20). We suggest downloading this file and having it available (e.g. on a thumb drive) in case it is needed.

Computer lab vs personal laptops

While students can use a computer lab or work on individual laptops, we suggest the latter. Installing Jupyter Notebooks on laptops is straightforward, gives the students a valuable experience, and allows them to complete work at home, if needed. Furthermore, the student has the computational tool available to them after completion of the activity.

Assessment

Successful completion of the CGI module is expected to be indicative of meeting the learning objectives. Assessment includes in-class assessment of the module as students work as well as grading of completed notebooks and Pause for Analysis responses. The zipped Assessment file provided with the materials includes the following:

  • sea_ice_melt_1_key.ipynb
  • sea_ice_melt_2_key.ipynb
  • sea_ice_melt_3_key.ipynb

References and Resources

Climate change videos:

References