Compl
e
te the Two lab writes ups at the bottom of these assignments.
1.
Summarize the relationship between accumulation and ablation over the course of a glacier.
What relationship between accumulation and ablation is necessary for glaciers to form? How
wil
l the relationship between accumulation and ablation change b
etween a glacier
’
s head and
its toe? How will it change between winter and summer?
2.
Compare and contrast the Nabesna and Athabasca Glaciers. Identify
and describe
three
dimensions of climate which cause the Nabesna Glacier to extend over a much la
rger distance
than the Athabasca Glacier. (HINT: remember our framework of
climate controls
—
how
will they
affect the
relationship between accumulation and ablation?)
3.
In our video tour, we contrasted summer and winter
(or, at least, late
–
spring)
views of the
Victoria and Lefroy glaciers. Although snow accumulates nearly everywhere during the winter
months, in o
nly a few areas does this snow endure to form glaciers. What is special about these
areas of glacial formation?
4.
The glaciers we examined in the Canadian Rockies all end at 6700
–
7500
’e
levation. Why
do
glaciers not extend below this altitude?
(HINT: What effects will altitude have on the
relationship between accumulation and ablation?)
5.
What landforms indicate the previous influence
of glaciation
in the valleys below the Athabasca,
Victoria, Lefroy, and Bow Glaciers?
6.
What elements of the landscape near Geor
getown, Colorado, indicate the presence of glaciers
in Colorado
’
s past? How can you tell that
this glaciation took place in the distant past, in
contrast to the relatively recent glacial activity in the Canadian Rockies?
Lab Assignment 1: Climate Comparison of Two Oregon Cities
In this assignment, you will explore the effects of mountains on climate, by comparing the climates of
two Oregon cities. You will access NOAA Climate Normals data, enter it into Microsoft Excel, and create a
pair of climographs, illustrating the average temperature and precipitation of each. This assignment thus
has several objectives: first, you will gain a better understanding of the role that mountains can play in
influencing climate, by comparing the models discussed in class with real-world data. Second, you will
also practice some basic skills related to data access, entry, and analysis.
Please work through the steps outlined in this document, jotting down your thoughts and responses to
questions as you go. You do not need to turn in your answers to all the questions. Instead, you will
need to turn in a write-up, consisting of the questions in Part V, along with your completed climographs
for Eugene and Bend.
Part I: Reviewing our Class Models
In class, we explored climate in terms of four major climate controls. Review your notes, and briefly
summarize how each of these controls affects the temperature and precipitation of an area.
•
Latitude:
•
Altitude:
•
Continentality:
•
Topography:
We further explored the effects of topography on climate through an idealized demonstration of the
Orographic Effect on a hypothetical mountain.
•
What variations of temperature did the model predict, as an air mass moved from the windward
side of the mountain to the leeward side?
•
How might that movement also suggest precipitation patterns? (Hint: where does condensation
occur?)
1
•
What assumptions does the model make about the structure of a mountain, or a mountain range?
Do these seem realistic? How do they compare to real-world mountains?
Part II: Locating Eugene and Bend
Eugene and Bend are two Oregon towns, with significantly different climates. What might account for
this difference? Use Google Earth to find out.
•
Locate Eugene and Bend. What is the elevation of the two cities? Approximately how far apart
are they?
•
In between Eugene and Bend lies a portion of the Cascade Range. Approximately what elevation
do these mountains reach? (HINT: This is much easier to see if you use a 3D view.)
•
Think back to our controls on climate. Brainstorm: compare and contrast Eugene and Bend, in
terms of their Latitude, Altitude, Continentality, and Topography. What effects would you expect
to see on the climates of the two cities?
Part III: Making A Climograph for Eugene
A. Access the Data
1.
Go to the NOAA National Climatic Data Center website at www.ncdc.noaa.gov. Under the tab entitled
“Data Access,” click on “Quick Links,” then click on the fourth item, “U.S. Climate Normals Products,”
and then click on “1981-2010 Climate Normals Data Access.”
2. Climate data comes in many forms! Scroll down to the FAQs to learn a little bit more about this
dataset. You will use this information in your lab write-up.
3. Now let’s get the data! Use the Search Tool (linked under “Data Access” at the top of the same page)
to access Monthly Normal Data. Select your US state of interest (Oregon) and then select the Eugene
station (Eugene Mahlon Sweet Airport, OR US). This may take a little time to load, but it will show the
2
monthly normal temperature and precipitation data, displayed neatly in a table and in a simple line
graph.
B. Enter the data in Excel
Although the line graph provided on the website is useful for quickly analyzing some trends, the way the
data are presented, the trends in precipitation do not stand out whatsoever. It essentially looks like
precipitation doesn’t change over the course of the year, when in fact it does. This is because
temperature and precipitation are on the same vertical axis. By putting the data in Excel and creating a
climograph, the patterns for both precipitation and temperature will become easier to interpret.
1.
Open Microsoft Excel and create a new spreadsheet. Save this spreadsheet in a place you’ll
remember. (It’s useful to keep a backup, and helpful to have a copy of your data to work on in
future.) Be sure to periodically save your work as you continue.
2. In cell A1, type the name of the location (in this case, Eugene).
3. Beginning in cell B2 and working across row 2 to cell M2, label each cell with an abbreviation to
represent each month (e.g. Jan, Feb, Mar).
4. Enter the term “Total Precipitation” in cell A3 and then enter the monthly amounts of
precipitation across the third row in cells B3 through M3.
5. Enter the term “Average Temperature” in cell A4 and then enter the monthly average
temperatures across the fourth row in cells B4 through M4.
3
C. Take a Closer Look at the Data
Complete the table below. In some cases, basic calculations will be needed. If you are comfortable with
formulas in Excel, these are easy to compute. Otherwise, a calculator or by-hand math will do the trick! If
your answer has more than two decimal places, please round to the hundredths place.
Table 1. Climate Trends for Eugene, OR vs. Bend, OR based on 1981-2010 Climate Normals Data – use the
the PRECIP (IN) and AVG TMP (°F) data.
Eugene, OR
Bend, OR
Precipitation in the wettest month (in)
Precipitation in the driest month (in)
Average precipitation for the 12 months (in) (mean of
the 12 months)
Range between the wettest and driest month (in)
Average temperature in the hottest month (F)
Average temperature in the coldest month (F)
The average of the average temperatures for the 12
months (F) (mean of the 12 months)
Range between hottest month and coldest month (F)
D. Create a Climograph in Excel
1.
Click and drag to select cells A2 through M4. With these cells selected, go to the insert ribbon. In
the charts section , choose Insert Line Chart. (It looks like
). Be sure to use an ordinary line
chart (ie, from the first column of the pop-up menu), rather than a stacked line chart.
2. If we display temperature and precipitation on the same vertical axis, we will have a hard time
seeing how precipitation varies over the course of a year. We will therefore add a secondary
vertical axis, for our precipitation data. Click once on the precipitation line so that all 12 points are
simultaneously selected. After you have selected these points, right-click, and select “Format
Data Series”. The resulting menu gives you the option to plot this data series on a secondary axis.
Voila! You now have two y-axes and the precipitation trends should already be much clearer.
3. We now want to reformat the precipitation series so that it displays as a column graph rather
than a line graph. With the precipitation series still selected on the chart (click once the
4
precipitation line to re-select if you need to), access the Change Chart Type tool. (This is on the
Chart Tools Design ribbon, along the top toolbar.) Within the “Custom Combination” options,
change the chart type for the Total Precipitation to Clustered Column (the first option).
4. Now make the graph more presentable.
a. Using the “Add Chart Element” tool in the Chart Tools Design ribbon, add some labels to
make the chart more readable. These should include a chart title above the chart that
clearly and explicitly explains what type of data is presented, and meaningful axis labels
for both the horizontal (time) axis, and both the primary and secondary vertical axes.
The vertical axes titles need to include the units. The labels you choose should allow any
viewer to easily understand what they are seeing!
b. Feel free to move things around a bit, resize font, etc. to make the climograph more
aesthetically pleasing.
What makes a good climograph?
Customarily, physical geographers use a line graph to show temperature, with a bar graph showing
precipitation. In order to clearly show the variation in each, climographs have two vertical axes—
one for temperature, the other for precipitation.
Creating these graphs in a spreadsheet program can be a challenge, using tools and settings that are
often buried in menus and properties-panes. The above instructions, and a video on the course
website, can help you design a good graph in Microsoft Excel. If you want to use another program,
plan to spend some time figuring out how to format your graph, perhaps with the aid of some
online searches.
Your submitted graphs should also include:
•
•
•
Clear titles for each graph.
Clear labels for your vertical and horizontal axes.
Indication of the units of measurement you are using.
Part IV: A Climograph for Bend
You will now repeat Part III for Bend, OR using the climate station “Bend, OR US.” You can simply cycle
through all of the steps again for Bend. You can create an entirely new Excel workbook for the Bend
data, create a new worksheet within your existing workbook file, or scroll down in your existing
worksheet. (Just be sure that you select the appropriate data to make the new graphs!)
As you add the Bend data to the summary data table and create a climograph for Bend, begin to compare
the two cities. What significant differences do you notice between the two cities’ climates? What might
explain these differences?
5
Part V: The Write-Up
You will now turn in a write-up that analyzes and interprets the climates of Eugene and Bend. , in light of
your data. This writeup should include your climographs (cut-and-paste them from Excel into Word), and
include data from your study. Be sure to phrase all answers in your own words—the goal isn’t just to put
words on paper, but to cement your understanding of the concepts!
1.
Which two of our four climate controls best account for the differences between mountain and
lowland climates? In your own words, describe their effects on temperature and precipitation.
2. Describe the geographic situations of Eugene and Bend, that you looked up in Part II. Why are these
cities a good case study for investigating the Orographic Effect? How does this case study compare
to the model of the Orographic Effect that we worked through in class?
3. In your own words, describe the processes that create the Orographic Effect. What will happen, in
terms of temperature and precipitation, as an air mass moves from the windward to the leeward side
of a mountain range? (Hint: in this case study, storms typically move from West to East. That is,
Eugene is on the windward side of the Cascades, and Bend is on the leeward.)
Some key terms that should appear in your response include the following: adiabatic cooling and
heating, dew point, condensation, and the rain shadow effect.
4. Compare and contrast the climates of Eugene and Bend based on the data you graphed. (Be sure that
your responses directly refer to the data in your climographs and data table.)
a. What precipitation patterns do you see for the two cities? How would you explain the
difference between the two cities’ precipitation totals?
b. What temperature patterns do you see in Eugene and Bend. Which city has the highest
average annual temperature? Which city has the highest range in average temperature
over the course of the year?
5. Do these patterns agree with our model of the Orographic Effect? What might explain the
difference? (Hint: think back to the four climate controls, and to the assumptions made in our
model.)
6. What temperature and precipitation patterns would you expect to see at a weather station located
high in the Cascades? (You don’t need to predict specific numbers, but outline what overall trends
you would expect to see.)
7. A friend, seeing your lab data, says “I was planning a ski trip to the Cascades this winter. I’m so glad
to see your data. Now I know that I should stay on the west-facing side of the mountain. There won’t
be any snow on the east-facing side!” Is that friend correct? What advice would you give them about
their winter plans?
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What to turn in:
Save your completed writeup (with climographs included), and submit it to the Canvas dropbox for this
assignment. D2L can read and understand Word documents or PDF files, but not Apple’s Pages.
Finally, keep saved copies of your excel file, and your writeup—Just in case!
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Lab 2: Exploring Glacial Landscapes in Google Earth
In this lab, you will use Google Earth to explore a series of glacial landscapes in Western North America.
You will identify a series of the glacial landforms we discussed in lecture, and at each site, I’ll pose
several questions that will (hopefully) help you connect what you see to the processes we’ve discussed.
As in Lab 1, you don’t have to submit all of your answers to these questions; however, you should think
through them, and jot down notes. At the end of the lab, I’ll ask you to submit a writeup addressing
several overarching questions.
Think of this as a virtual field trip—the goal is not only to answer the questions, but also to explore some
fascinating places. (This is a geography class, after all!)
Part I: A brief review
Think back on what we’ve learned about glaciers in lecture and our readings. (Note that while we
discussed both continental and alpine glaciation in lecture, our focus here is on alpine glaciation.)
The relationship between accumulation and ablation is key to understanding glacial formation.
In your own words, define what these terms mean. What relationship between accumulation
and ablation is necessary for a glacier to form?
Are accumulation and ablation constant across all points on a glacier? How will this relationship
between a glacier’s head and toe?
How will the relationship between accumulation and ablation change seasonally, during the
course of a year?
In module 3, we identified several factors which affect mountain climates at various scales.
Brainstorm: how will each of the following affect accumulation and ablation?
Latitude
Altitude
Continentality
Topography
The Orographic Effect and Rain Shadows
Slope Aspect
Terrain
Part II: Downloading the glaciers.kmz File
Hopefully you’re now somewhat familiar with the Google Earth Pro interface. (Past labs and activities
have introduced you to visualizing landscapes in 3D, measuring distances and elevations, and viewing
historical imagery—If you missed them or feel rusty, take a look back through!)
Just to repeat, you’ll need to have Google Earth Pro installed on a “real” computer for this lab. This is
different from the basic version, which runs on smartphones and tablets, but can also work in a web
browser. You need the Pro version.
To make things easier, I’ve compiled a collection of place-marks in Google Earth. Download the
glaciers.kmz file from D2L and save it somewhere where you’ll be able to find it. Then, fire up Google
Earth. Once you’ve clicked through the introductory tool tips, go to File Open and select glaciers.kmz
This will show a number of placemarks under the “Places” Tab at the left side of the screen. You may
need to click the drop-down menu for “Temporay Places” to see all the placemarks. (You can turn off
and collapse the “Sightseeing Tour” to save some space.)
At the left side of the screen, the “Layers” tab lets you adjust which place-marks Google Earth displays.
(It’s immediately below “Places.”) Most of the time, the default view works well enough, but you might
want to turn off unnecessary layers to reduce visual clutter. (You’ll want to keep “Borders and Labels”,
“Roads”, and “Terrain,” and perhaps “Photos.”)
Part III: Glaciers in Alaska
1. The first placemark is for the Nabesna Glacier, in Wrangell-St. Elias National Park in Southeast
Alaska. Double-click “Nabesna Glacier” under the “Places” Tab.
The view starts as a top-down view. Shift to a 3D scene, and trace the course of the Nabesna
Glacier. Where does the glacier originate? Where is its outflow?
Based on the points you have identified, how long (roughly) is the Nabesna Glacier? How much
elevation change takes place over the glacier’s length?
(HINT: Google Earth will show you the elevation under your mouse pointer. To measure linear
distances, use the ruler tool
, but be sure to choose sensible units of measurement.)
Why is there so much more glaciation on the north side of the St. Elias Mountains than the
south side?
Zoom in to get an up-close look at the glacier. (You’ll see a somewhat awkward composite of
different imagery, but it’s not a huge problem right now.) What are the extended stripe-like
structures below the confluence of the glacier’s two forks?
Part IV: Glaciers in the Canadian Rockies
1. Next, double-click on the “Athabasca Glacier” placemark. This will take you to Jasper National Park,
on the Alberta/British Columbia Border. The Athabasca Glacier is one of several glaciers descending
from the Columbia Icefield—often referred to as the hydrological apex of North America. These
descend north to the Mackenzie River and the Arctic Ocean, east to the Saskatchewan River and
Hudson Bay, and west to the Columbia River and the Pacific. The Athabasca Glacier is one of the
world’s most accessible and famous glaciers.
The default view in Google Earth shows imagery from March 2019. Does this make it easy to
identify the glacier, or to measure its length?
To get a clearer view of the glacier’s extent, use the historical imagery feature. Return your view
to a top-down image (you can do this by double-clicking the “Athabasca Glacier” placemark in
the list of places). Then, click the
button on the toolbar, and select the imagery from July
7, 2015. What is different between the March and July imagery? What does this tell you about
the changing balance of accumulation and ablation during the course of the year?
Near Sunwapta Lake at the toe of the glacier, there is a 3D photo-sphere, accessible with the
icon on the map. (You may need to turn on photos in the Layers panel to see it.) Double-
click on this icon to view a user-contributed panoramic view of the glacier’s toe. Next, click “exit
photo” to see the glacier in Google Earth’s 3D-rendered view. (You may need to pan the view,
or “look up” using the view controls.)
Try to recreate the view from Gadd’s Handbook of the Canadian Rockies shown below. What
features can you identify?
Measure the length and elevation change of the Athabasca Glacier. How does it compare to
what you measured for the Nabesna Glacier? Brainstorm several reasons that might explain this
difference.
Turn off historical imagery. Meltwater from the Athabasca Glacier feeds the Sunwapta and
Athabasca Rivers, which flow (north) to Jasper. Trace this valley downstream. At several points,
zoom in, using a 3D view. What do you notice about the shape of the valley? What does it
suggest about previous glacial activity in the area?
2. Next are the Victoria and Lefroy Glaciers. These are located close together, above the Plain of the
Six Glaciers, which is itself high above the famous Lake Louise. Click on either placemark—you
should be able to see both glaciers.
First, zoom in to get a feel for the two glaciers. Explore a 3D view (Hint: look from the northeast
to the southwest). This is impressive mountain scenery, but it is difficult to identify the precise
extent of the two glaciers.
Because of this, I have prepared a brief video tour of these glaciers, accessible as part of the lab
materials posted to Canvas. Watch this video, then explore on your own.
(HINT: If you turn on historical imagery, do so from a top-down, vertical view, before adjusting
the display to 3D.)
Some things to think about as you explore:
o What is a cirque? How do cirques increase snow accumulation, and reduce snow
ablation?
o
What is a firn line? What can a firn line tell you about the seasonal balance of
accumulation and ablation?
o
Finally, trace the valley down toward Lake Louise. What signs of recent glacial activity
and retreat are visible in the landscape?
3. Be sure you have turned off historical imagery, and select the placemarks for “Bow Lake” and “Bow
Glacier Falls”. The Bow Glacier has retreated dramatically during the past hundred years, but you
can see where it descends from the Wapta Icefield.
Identify the small, roughly circular lake to the southwest of Bow Glacier Falls. A century ago,
this lake lay under the Bow Glacier! Trace a path downhill from the Bow Glacier toward Bow
Lake. What (post-)glacial landforms do you see?
What in the landscape might help you estimate the timeframe of the glacier’s retreat?
Part V: Post Glacial Landscapes in Colorado
1. Select the last placemark, for Georgetown, Colorado. Zoom in and tilt the view to look at the
mountains immediately south and southwest of the town.
Examine the two valleys that come together just above Georgetown. What do they suggest
about the formation of this landscape?
Follow the valley of Clear Creek downhill (along I-70, northward and eastward toward Denver.)
How far down-valley does the U-Shaped glacial valley extend? Do you see any clear sign of a
terminal moraine?
In contrast to the Canadian examples above, these areas have not been actively glaciated since
the last ice age—some 10,000 years. What might have happened to the terminal moraine in the
intervening time?
Part VI: The Writeup
Thus far, I’ve asked you to look at a number of glaciers, to measure them, and to think about the
processes operating across seasonal, annual, and longer-term time-scales. Now, it’s time to bring
together what you’ve learned. In a separate document, please answer the following questions. Your
answers should be 1-2 substantial paragraphs each. Use your own words, and cite specific examples
from our explorations. Submit your writeup to the Canvas dropbox.
1. Summarize the relationship between accumulation and ablation over the course of a glacier.
What relationship between accumulation and ablation is necessary for glaciers to form? How
will the relationship between accumulation and ablation change between a glacier’s head and
its toe? How will it change between winter and summer?
2. Compare and contrast the Nabesna and Athabasca Glaciers. Identify and describe three
dimensions of climate which cause the Nabesna Glacier to extend over a much larger distance
than the Athabasca Glacier. (HINT: remember our framework of climate controls—how will they
affect the relationship between accumulation and ablation?)
3. In our video tour, we contrasted summer and winter (or, at least, late-spring) views of the
Victoria and Lefroy glaciers. Although snow accumulates nearly everywhere during the winter
months, in only a few areas does this snow endure to form glaciers. What is special about these
areas of glacial formation?
4. The glaciers we examined in the Canadian Rockies all end at 6700-7500’ elevation. Why do
glaciers not extend below this altitude? (HINT: What effects will altitude have on the
relationship between accumulation and ablation?)
5. What landforms indicate the previous influence of glaciation in the valleys below the Athabasca,
Victoria, Lefroy, and Bow Glaciers?
6. What elements of the landscape near Georgetown, Colorado, indicate the presence of glaciers
in Colorado’s past? How can you tell that this glaciation took place in the distant past, in
contrast to the relatively recent glacial activity in the Canadian Rockies?