Draft Basic Lesson 2
Studying Topography, Orographic Rainfall, and Ecosystems (STORE)
Basic Lesson 2: Using Google Earth to Analyze
the Connection between Topography and Rainfall
Introduction
This lesson introduces Geographical Information Systems (GIS) to the students. Students learn to
read the data contained in the map and use basic GIS functions. GIS in this lesson is essential to
understanding the relationship between topography and rainfall. Future lessons in STORE will
build upon the scientific and GIS understanding that the students take away from this lesson.
This lesson focuses on the California Study Area (see Figure 1 below).
The meteorology GIS data used in this lesson comes from data distributed by the National
Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC).
NCDC has the largest archive of national and global quality controlled weather data. NCDC
distributes weather data collected by surface meteorological instruments operated by the
National Weather Service and other government agencies. Many of these stations are located at
airports and other public facilities. As an example, the San Jose and Modesto weather stations
are located at San Jose International and Modesto City County Airports, respectively and the
Sonora weather station is located at a U.S. Forest Service Ranger Station.
Image 1. California Study Area
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Draft Basic Lesson 2
Objective
To introduce and teach the basics of GIS to the students. To challenge students to see rainfall
patterns over mountains and valleys.
Lesson Duration
1/2 class period, 20 to 25 minutes
Requirements

Google Earth software

Download “STORE CA Data.kmz” or “STORE Data.kmz”.
Part 1 – Set up
1. Open Google Earth from your computer. Once Google Earth (GE) is open, click “File” at
the top right corner of the Google Earth window, and click on “Open” from the drop
down menu. In this window, navigate to the “STORE CA Data.kmz” or “STORE
Data.kmz” file downloaded on your computer. Once you have selected the kmz file, click
“Open”. (Note: the file names may also include a date, because revisions have been
made from time to time).
2. Save “STORE Data” file in GE to “My Places” by dragging and dropping the folder into
“My Places” under the “Places” Panel on the right of the screen.
3. Tip before you start: It can get confusing when you have multiple layers selected at once
and multiple folders and subfolders open. To avoid confusion, close layers, folders and
subfolders you are finished with before opening new ones.
Part 2 - Learn how to read the map layers’ tabular data in Google Earth
4. Five weather stations (e.g., Twin Lakes, Sonora RS, etc.) within the California Study
Area may already be displayed on the map. If they are not, click the box next to the
subfolder called “CA Weather Stations” within the Places Panel on the left side of your
Google Earth window. By clicking that box, a check mark appears and the five layers
in the subfolder become visible on the map – one layer for each weather station.
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Draft Basic Lesson 2
Notice also that when you click the box to the far left of the CA Weather Station
subfolder the + sign changes to a – sign (or in other Google Earth versions, a right-facing
carrot/arrow ( ) changes to a downward-facing arrow ( ). This means that you’ve
opened in the Places Panel the names of the five layers about the individual weather
stations. You should now see that all five weather station layers are checked (see the
blue-circled area) because you just turned them on with one click at their parent folder
“CA Weather Stations.” You can check and uncheck them individually or from the parent
folder.
Click on any one of the weather stations to view a table of information about that station.
You must click on the red dot and not on the name of the weather station. The table
appears in a “pop up window” on the map next to the weather station.
Each table includes the following information:
Longitude (in decimal degrees)
Latitude (in decimal degrees)
Station (in station name)
Elevation (in meters above sea level)
AnnAvgTmp (annual mean temperature °F)
JanAvg (January mean monthly temperature °F)
JanAvgLow (January mean daily temperature °F)
JulAvg (July mean monthly temperature °F)
JulAvgHigh (July mean daily temperature °F)
AnnPrecip (mean annual precipitation in inches)
JanPrecip (January mean precipitation in inches)
JulPrecip (July mean precipitation in inches)
AnnSnow (mean annual snowfall in inches)
5. To close the popup window, clicking on the “x” in its upper right corner.
Question 1: Open each weather station’s information one-by-one and examine the
values. Which station recorded the most annual precipitation? How does elevation at this
weather station compare with the elevation of the other weather stations? Do precipitation
and elevation appear to be closely aligned at all five of the weather stations?
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Draft Basic Lesson 2
Part 2 - Visualize variations in precipitation corresponding to changes in elevation
(Orographic Rainfall)
1. Keep the weather station layers on the map. In the Places panel, click the box
the layer name “Terrain Path through the Weather Stations”.
next to
A check will appear in the box and a terrain path will open on your map. The path
intersects each weather station. If you click this box again, the box will become
unchecked and the layer will disappear from the map. This is how you turn map layers on
and off.
2. You will now call up an “elevation profile” of the terrain path to examine the topography
along the path. First, make sure that you’ve select the layer “Terrain Path through the
Weather Stations by clicking its name. You will know if is selected when a blue frame
appears around the name. Then, click “Edit”. A menu of editing choices should appear on
top.
3. In the list of choices, click “Show Elevation Profile”. An elevation profile of the terrain
path will appear. It is a cross-sectional view showing the changing elevation and
topography. In other words, it is a two-dimensional view that mimics what you would see
from the ground if you were looking at a vertical slice (i.e., cross-section) of land with all
of its changes in elevation.
4. Move your cursor along the elevation profile to study the changing elevation by clicking
anywhere on the profile’s moveable dark vertical line. To move the line, hold the mouse
down, move it, then release the mouse. Notice that the location of that vertical line on the
elevation profile appears on the map as a thick red arrow.Notice also how the values
displayed on the map correspond to the values on the elevation profile.
NOTE: The terrain path through the weather stations has been pre-developed for you as a
layer. However, you can also create your own terrain paths and make your elevation
profiles for them. To create your own path, click on the path-creation icon:
It is the fourth icon from the left on the horizontal bar at the top of the Google
Earth window. .
A dialog box will then appear on top of the map with a default name: “Untitled Path.”
In the dialog box, first replace “Untitled Path” with a meaningful name (such as “My path
through mid-California”). Then, keep the dialog box on the screen and draw your path. If
the dialog box is in the way, you can resize it by clicking lower right corner, then holding
your mouse down and making it smaller. You can also move it around by holding the
mouse anywhere on it and dragging it to a better spot out of the way). (NOTE: do not
close the dialog box until you have completed drawing the path. Otherwise you
cannot draw it.)
To draw your path, click once with your mouse at the place where you want the path to
begin, then drag the mouse to the place where you want it to end, then click again. This
will create a path with a single line segment. If however you want to create a path with
more than one line segment, continue drawing new segments with your mouse and
clicking where you want each segment to end. If you want to change the shape of one of
the segments, simply click the segment, hold the mouse down and move it. When you are
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Draft Basic Lesson 2
done moving it, let up on the mouse. Your path will appear on the map as a thin white
line.
When you are done drawing your path, click the OK button on the path dialog box.
Notice how the dialog box then disappears but the name of the path appears on the Places
panel. If you don't like where it appears on the panel, hold your mouse down on the path
name and move it somewhere else. Once you’ve created your path, you can bring up an
elevation profile for it just like you did for the path through the weather stations.
5. Keeping the weather station and terrain profile layers open, you will now study layers
showing 30-year averages of annual amounts of rainfall. Each layer consists of a single
polygon representing an area on the map that has a certain range of values for average
annual precipitation totals, such as from 5.01 to 12 inches, 12.01 to 20 inches, etc. To
make these layers visible on the map all at once, click the box in the Places panel next to
the subfolder called “Recent Average Annual Precipitation Totals” (circled in red on
Image 2). When you click the box, a check will appear in it and your map will look like it
does in Image 2.
Image 2:
TIP: You can zoom in and out of the map area, depending on how much detail you want
to see. To zoom, scroll your mouse over the top right corner of the map area. A toolbar
for zooming in and out should appear below a compass rose.
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Draft Basic Lesson 2
Question 2: As you move your eye along the terrain path, what pattern do you see in
precipitation in relation to elevation? Based on your understanding of orographic rainfall (first
introduced in Basic Lesson 1), provide a simple explanation as to why this pattern occurs. For
another view of the terrain, examine Figure 2.
Figure 2. Average annual precipitation overlain on a topographic relief map for the California
Study Area. The darker blue areas over the land represent greater average annual precipitation.
Additional Information
The Hydrologic Cycle at http://snow.cals.uidaho.edu/clim_map/koppen_usa_map.htm. This link
shows how climate zones in the US are very closely related with elevation. Mountainous areas
have colder/wetter climates than adjacent lower areas.
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