Wind Chill
Objectives:
Students will define wind chill.
Students will make a graph of the data they collect.
Standards Assessed: Benchmarks
Earth Science:
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Grades 3-5: D. Analyze weather and changes that occur over a period of time.
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Grades 6-8: C. Describe interactions of matter and energy throughout the lithosphere, hydrosphere and atmosphere (e.g. weather).
Procedure:
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Discuss the concept of wind chill. Do students feel colder when the wind is blowing? Is there a way they can find out what the wind chill is on a given day? (News shows and Web sites listed below)
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Have the students find whether movement of the air or wind affects the temperature that we feel.
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Prepare a pan of water with about .5 inch of room temperature water. Lay a thermometer in the water with the ball of the thermometer submerged. Take the temperature at the time you put the water in and then again five minutes later.
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Have the students make a hypothesis of what they think will happen.
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Put a fan by the water so that the air from the fan blows over the water. Wait about 20 minutes and again check the temperature. (Be careful! Don't get the fan or the cord of the fan wet!)
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Plot the points on a graph on the board.
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Students will write a summary of the graph and then answer the questions, "How does moving air or wind affect the temperature of the water? What do you think you could do to stay warm?"
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Have students go to http://www.nws.noaa.gov/om/windchill to see the chart of wind chill factor (or the teacher could print the chart and distribute to students).
Materials:
Evaluation:
Points Criteria
| 0, 5, 10 |
Heading, Title, Problem and Hypothesis are listed. |
| 0, 5, 10 |
Materials and procedure are explained. |
| 0, 10, 20 |
Data points were included and defined. |
| 0, 10, 30, 50 |
A clear conclusion that explains the results of the procedure is given. |
| 0, 5, 10 |
Mechanics (grammar, spelling, punctuation, etc.) |
Enrichment:
Older students might want to calculate the wind chill factor using the information below.
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Formula to calculate a Fahrenheit wind chill.
T(wc) = .0817 ?3.71V0.5 + 5.81 -0.25V)(T - 91.4) + 91.4
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T(wc) Wind Chill
V Wind Speed in statute miles per hour
T Temperature in degrees Fahrenheit
Note: When wind speeds are below four miles per hour, the above formulas will give you a wind chill that is higher than the actual temperature. When wind velocities are near zero and you are standing still, your body heat warms the air near your body. This warm air near your body provides some insulation from the colder environment. As a result, it may feel warmer than the actual temperature.
Source for both formulas: The National Weather Service
http://www.5cities.com/weather/wind_chill_formula.htm
Extra-credit:
Students can determine from a wind chill graph when it would be dangerous to be outdoors.
Source for the formula: The National Weather Service
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