Overview

Sure, skiing the Greatest Snow on Earth is fun, but it's not always possible and in some parts of the world artificial snow is critical for skiing. In this learning activity, we examine the importance of both temperature and humidity for snowmaking. After completing this activity, you should be able to ascertain whether or not snowmaking can occur at your favorite resort if nearby temperature and humidity observations are available.

Instructions

Utilize the information located in the Scenario and Key Concepts to answer the questions located in this activity. This knowledge check contains 15 multiple-choice questions and is not timed. You may refer to the textbook, videos, or your notes to help you work through the assigned questions. You will have two attempts to complete this activity. The highest grade will automatically be recorded. Once you have submitted your activity for a second time, you will be able to see the correct answers. Discuss with your instructor if you have questions about your answers or feedback.

Activity is due Sunday, by 11:59 p.m. MT

Submission and Assessment Guidelines

You will complete the quiz associated with this scenario within Canvas. For help on how to take a quiz in Canvas, review How do I take a quiz.
This learning activity is worth 9 points toward your final grade.

Scenario

After graduating from the University of Utah, you've accepted a well-paying position in Saratoga Springs, NY. It's a popular tourist destination, known for thoroughbred horse racing, but for skiing, knowing how the snowmaking conditions have been at your favorite resort is critical for finding adequate snow coverage and decent ski conditions.

It is midnight on New Years and you've just watched the ball drop in Times Square. You and your friends have decided that perhaps you'll try to get up early and ski at Killington tomorrow. By eastern standards, Killington is a large resort and it has an excellent snowmaking system if the weather cooperates. The question is, has the weather cooperated?

Key Concepts

a. Temperature, humidity, and wet-bulb temperature

For snowmaking, it isn't the temperature that matters, but the wet-bulb temperature. The wet-bulb temperature is the minimum temperature to which air can be cooled through evaporation. It depends strongly on humidity. When the humidity is low, the wet-bulb temperature can be several degrees or lower than the actual temperature, sometimes enabling snowmaking when the temperature is actually above freezing. On the other hand, when the humidity is high, snowmaking can be difficult when temperatures are just below freezing.

Calculating wet-bulb temperature is actually very difficult! I won't subject you to the torture. However, if you have access to observations of temperature and humidity (or dew point) from at or near your local ski area, you can calculate it easily by Googling "wet-bulb calculator." Click here for one site at which you input temperature and relative humidity to get wet-bulb temperature.

b. Observations by Killington

MesoWest is a program at the University of Utah that provides access to tens of thousands of weather observations across the United States. Near Killington, the Vermont Agency of Transportation provides observations from the Route 4 Mendon Mountain observing site (identified by the letters "VTMNM") just north of Killington at an altitude of 2,139 feet/652 meters [remember to right click and select "Save As" to download a larger, higher resolution version of any of the figures below]. With lifts between 1,165 and 4,241 feet, this site is broadly representative of the conditions at Killington (although it's not perfect).

Maps of Vermont and the Killington areas with the Mendon Mountain observing site annotated

Figure 1. Left: Google maps terrain map of Vermont and the surrounding region. Right: Google maps satellite view of Killington ski area and the location of the VTNMN observing site.

In Figure 2 are graphs showing temperature (red line), wet-bulb temperature (green line), and relative humidity (blue line) during the 7 days prior to your possible trip. Dates and times are based on Eastern Standard Time, with 00:00 representing midnight and 12:00 representing noon. Note that where temperature and wet-bulb temperature are the same, the red temperature line covers the green wet-bulb temperature line.

Temperature and wet-bulb temperature graph

Relative humidity graph

Figure 2. Graphs of temperature (red line), wet-bulb temperature (green line), and relative humidity (blue) during the 7 days prior the possible ski trip. Source: MesoWest.

Citations

Scenario:

- - Wet Bulb Calculator
    - Citation: Omni Calculator. (n.d.). Wet bulb calculator.
  - MesoWest
    - Citation: MesoWest. (n.d.). States. University of Utah.

Images:

Key Concepts