|Climate has a strong influence on the types of plants, plant communities, and, in turn, animal communities found within Yellowstone National Park. Understanding climate patterns in the Park will help us to develop a baseline for understanding the more complex ecological processes operating there. Climate Diagrams are one tool that scientists use to explore the relationship between the type and distribution of terrestrial ecosystems and the climate. The diagrams summarize annual variation in temperature and precipitation, the length and intensity of wet and dry seasons, and the portions of the year during which average minimum temperature is above and below 0 degrees C. A sample climate diagram is included at the end of this document.
In this exercise, you will compare the climate (temperature, precipitation) at different elevational locations within Yellowstone National Park:
- West Yellowstone, MT (the west entrance of Park, low elevation, mainly forest)
- Old Faithful, WY (located in the mid-elevation, geothermally active, Firehole Valley)
- Lake Yellowstone, WY (near the Hayden Valley, a higher elevation meadow complex)
Go to the web page of the Western Regional Climate Center located in Reno, NV (www.wrcc.dri.edu), and access the Western US Climate Historical Summaries Database:
http://www.wrcc.dri.edu/climsum.html (Western US, by state)
Using the WRCC web site, compare and contrast the climate in three different regions of YNP. For each of your three regions, construct climate diagrams using the 1971-2000 (30-yr) climate averages. Climate diagrams are simply graphs of average monthly temperature (y-axis 1) and precipitation (y-axis 2) plotted by month (x-axis). The data can be cut and pasted from the WRCC web site directly into your Excel spreadsheet, where you can plot your data. Temperature data must be in degrees C and precipitation data in millimeters. In order for your climate diagram to look like the one attached, you must adjust the temperature and precipitation scales so that 10 degrees C lines up with horizontally with 20mm of precipitation.
In addition to the 3 climate diagrams, create 2 Excel graphs that compare average snow depth in the 3 locations (monthly) and average annual snowfall in the 3 locations.
Please answer the following questions in your write-up:
- What is the climate of Yellowstone like? What are the 3 locations that you are comparing?
- How do they differ in elevation and location?
- Do monthly air temperatures (maximum, minimum, annual range, etc.) vary between your 3 locations? If so, how and why?
- Do monthly and annual precipitation (months of max, min precip, total annual precip, etc.) vary between your 3 locations? If so, how and why?
- How does average snow depth differ between the 3 sites by month? How does average annual snowfall differ between the 3 sites?
- In summary, what are the primary controls on Yellowstone's climate?
It is recommended that you use Excel or some other type of spreadsheet program to analyze and display your data, as well as to create graphics for your write-up. Any graphics should be incorporated neatly into your word-processed write-up.
Some conversions that may be helpful:
Degrees C = ( degrees F – 32) / 1.8
Millimeters = Inches x 25.4
Final write-up for homework should include:
- 3 climate diagrams
- 1 snowpack comparison diagram
- answers to questions