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Snow cover by Latitude
Purpose: Using data sets from MYNASADATA students will create graphs comparing the amount (percentage) of snow cover along selected latitudes by date.
Grade Level: 6-8
Estimated Time for Completing Activity: One class period
Learning Outcomes:
  • Create graphs showing the amount of snow coverage at various points of latitude
  • Compare graphs
National Standards:
  • Science Content: D Earth and Space Science
Virginia Standards of Learning:
  • ES.3: The student will investigate and understand how to read and interpret maps, globes, models, charts, and imagery.
  • ES.3d: The student will investigate and understand how to read and interpret maps, globes, models, charts, and imagery. Key concepts include location by latitude and longitude and topographic profiles.
Prerequisite:
  • Basic graphing skills
  • Familiarity with using longitude and latitude
Tools:
  • Graph paper
  • Graphing utility (e.g. MS Excel)
  • Atlas
Vocabulary:
Lesson Links:
Background:

Lines of latitude are sometimes used to define broad climatic regions. For example, the polar regions exist between 66.5 and 90 degrees N or S. Because these lines are imaginary they can intersect many different kinds of geological features, land types and land coverings. By measuring the amount of a particular type of land cover, in this instance ice, scientists are able to determine the growth or shrinking of glaciers or snow cover in general.

This lesson asks that students pick a latitude and compare the amount of snow cover over the range of longitudes that the chosen latitude intersects. Data for this lesson comes from the International Satellite Cloud Climatology Project (ISCCP). ISCCP computes fractional snow and ice coverage from satellites scanning the Earth using visible, infrared and microwave imagery.
Procedure:

1. Obtain a blank map and draw a horizontal line across the selected latitude. Using an atlas for reference mark at least four large cities near this line.
2. Access the MY NASA DATA website to access a data set. (or use the one provided)
3. Select: Live Access to Data
4. Click on Live Access Server
5. Select Dataset: Snow and Ice
6. Select variable: Monthly Snow Ice Amount (ISCCP) Click Next.
7. On the parameters page, select: View: Longitude line (x), Output: Table of Values (text), Region: Full Region
8. Coordinates are 45N, 130W, 60W, 45N.
9. Dates are Jan 15 2001
10. Click Next to produce the output.
11. To prepare a line or bar graph of the snow cover data do the following:

A. Select and copy the data only. Open Excel and Paste into a worksheet. You will have two columns of numbers. Click on B, then use the Insert menu to add a column in front of Column B. Now click on A to select all of Column A. Under the Data Menu, Select Text to Columns.
Text Import Wizard:
-Step1: Select Delimited(usually the default selection), Click Next.
-Step2: Select Space. In addition to Space, check Other, in the box beside Other put a capital W inside. Click Next, then Finish.

B. You should now have 3 columns of data in your spreadsheet, but you only need two.
-Click on B (of Column B), right mouse click, delete. There should now be 2 columns of data.

C. To make the bar graph:
-Highlight column B, click on Chart Wizard or Insert menu then Chart
-Step 1: Select Chart type (Column is the default). Click Next.
-Step 2: Select Series Tab, Category (X) axis labels: click on symbol next to the text box, highlight Column A, click on symbol again to finalize choice. Click Next.
-Step 3: Name the chart and axes, Title: Snow cover over North America at latitude 45 degrees North, x-axis: longitude, y-axis: percent (type symbol or word) snow cover. You can choose whether to have a legend or other features. Click Next.
-Step 4: Choose your preference of whether to have the chart appear within your spreadsheet (default) or on a seperate page (As new sheet). To see an example of what you should get, click on Data and Graph in the Links section.

11. Mark the selected cities on the graph.
Questions:

1. Does the amount of snow cover vary by longitude? Suggest reasons why or why not.

2. How does the amount of snow compare across a line of longitude?

3. Does longitude control the amount of snow present?

4. What else might contribute to the amount of snow cover?
Extensions:

1. Using an atlas locate four large cities near the line of latitude, using a topographic reference list the elevations of these cities, each person in the group is to locate climate data for one city and share with the group.

2. Using the information you have now gathered, would you change your answer to question 1? Why or why not?

3. Create data sets and graphs of other locations (latitudes). Compare to elevation and seasonal changes.

4. Consider whether El Nino might have an effect on your results. Explore the same data for 1997-98, when a major El Nino occurred. Does this change your conclusions?

Lesson plan contributed by Jodie Harnden, Athena, OR

Click here for Teachers Notes

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