DataStreme Activity 4B:

HEATING DEGREE-DAYS AND WIND CHILL

Do Now:

  1. Print this file.
  2. Print the Wednesday Image 1 and Image 2 Files.
  3. Print (when available) the Thursday, 5 October 2000, Daily Summary File.

To Do Activity:

  1. Read Chapter 4 in STUDY GUIDE, Part A: Narrative.
  2. Go to STUDY GUIDE, Part B: Applications. Start Activity 4B.
  3. Return here (Wednesday Activity B File) when told to do so.

Go To STUDY GUIDE - Activity 4B Now


WELCOME BACK: Procedure continued from STUDY GUIDE.

  1. Heating and Cooling Degree Days and wind chill values are calculated with the use of observational data collected at weather stations. Image 1 is the map of maximum temperatures, in degrees Fahrenheit, at selected stations across the coterminous US during the preceding 24-hour period, ending at 12Z on 04 OCT 2000. The highest maximum temperature reported on the map was ______ °F at [(Blythe, CA) (Oklahoma City, OK)]. The lowest maximum temperature was ______ °F at [(Havre, MT) (Caribou, ME)].

  2. Image 2 is the corresponding map of minimum temperatures across the coterminous US during the same 24-hour period also ending at 12Z on 04 OCT 2000. The lowest minimum temperature reported on the map was _______ °F at [(International Falls, MN) (Burns, OR)]. The highest minimum temperature was _______ °F at [(Phoenix, AZ) (Orlando, FL)]. (The Miami minimum is 73 °F.)

    The maximum and minimum temperature patterns reflect the cool, fair weather High that has settled into the northern Plains and the warm air across the Southwest that set record temperature values.

  3. The following table lists some selected cities with their temperature maxima and minima. For each, calculate the average daily temperature and determine whether Heating Degree Day units or Cooling Degree Day units were produced and how many. (Following NWS practices, the mean daily temperature is rounded up to the nearest whole degree, if necessary, before calculating HDD or CDD.)

    Degree Day Units
    City Max. T (°F) Min. T (°F) Mean T HDD/CDD Units Circle which
    Pocatello, ID 63 41 ________ ________ HDD / CDD
    Phoenix, AZ 98 78 ________ ________ HDD / CDD
    Havre, MT 40 28 ________ ________ HDD / CDD
    Peoria, IL 80 50 ________ ________ HDD / CDD
    Brownsville, TX 92 70 ________ ________ HDD / CDD
    Caribou, ME 68 46 ________ ________ HDD / CDD
    Memphis, TN 91 67 ________ ________ HDD / CDD

  4. Comparing the maximum and minimum temperatures shown on the maps with the degree day values you calculated, it can be seen that utility energy usage in the US during this period was directed toward [(heating) (cooling)] across the Northern US states while [(heating) (cooling)] may have been needed more across the Southern US.

  5. Look at the Image 2 map of minimum temperatures. Missoula, Montana, had a minimum temperature of 30 °F during the previous 24 hours. Assume that at the time the temperature was 30 °F, the wind speed was 5 miles per hour. Using Table 4.3, the windchill equivalent temperature (WET) for this combination of temperature and wind speed would have been ______ °F. This would have been the same as the temperature in calm air at [(International Falls, MN) (Fargo, ND)].

  6. For the same temperature (30 °F), if the wind speed were 15 mph, the WET would have been ______ °F. And for 30 °F and 25 mph, the WET would be ______ °F. The 5 to 15 mph wind speed increase produces an WET difference of ______ F° in equivalent heat loss to the body, while the 15 to 25 mph increase brings only a WET difference of ______ F° in equivalent heat loss to the body. The WET table shows that increasingly higher wind speeds (beyond approximately 25 mph) produce little additional cooling effect in WET values.

The DataStreme homepage also provides current hourly data at many locations within each state in the Surface section, under "State Surface Data - Text" and graphically as "Meteograms for Selected Cities". These data can, among other uses, be employed to calculate WET for your location.

The National Weather Service Internet site provides current meteorological data for any selected station (by state and city) for the US. These data also include a station's daily maximum and minimum temperatures. The Web address is: http://weather.noaa.gov/weather/ccus.html.


Note: If pressure blocks were already distributed to you, be sure to bring them to the Mid-course meeting. See Study Guide Part B: Applications, Activity 5B.

If you witness or experience unusual or interesting weather events, please email them to Ed Hopkins (address at end of Daily Summary files) for possible inclusion as a "Report from the Field". Your experience may be of interest to other DataStreme participants and their students. They add the human element to weather.


Faxing Instructions:

After completing this week's applications, fax the following pages to your LIT mentor by Monday,
9 October:

  1. Chapter 4 Progress Response Form from the Part B: Applications binder, Week 4, or the DataStreme Homepage Progress Response Form,
  2. 4A and 4B Activity Response Form,
  3. STUDY GUIDE, Part B: Applications, page 4A-2,
  4. U.S. - Data map of 00Z 25 SEP 2000 (Monday Image 1 with isotherm analysis and cold front), and
  5. STUDY GUIDE, Part B: Applications, page 4B-2.

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URL: datastreme/learn/b_act.html
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