Understanding wind chill in a cold snap
This week has been a chilly one, to say the very least! Many of you returned to online learning and working from home in order to stay safe during these frigid temperatures. I do have to be honest; this has been a pretty mild winter to date, so I am not going to complain… too much anyway!
With the temperatures dropping out there this week, I have had quite a few questions about the actual thermometer reading and temperature with wind chill and why we should wear lots of layers to keep us warm.
How does this work?
Well, we had better investigate this further. Let’s get started!
Remember to ask an adult before doing this experiment
Materials
• Fan
• Five small thermometers
• Kettle
• Water
• Room thermometer
• Table or sturdy work surface
• Notebook and pencil
• Measuring cups
• 250 mL styrofoam cup
• 250 mL glass cup
• 250 mL ceramic cup
• 250 mL plastic cup
• 250 mL metal insulated cup
• Shallow tray/cookie sheet to hold all of the cups
• Stopwatch
• Ruler
Procedure
• Check and record the inside temperature in your science notebook. Note: this is the temperature of the room you are working in.
• Draw a chart in your notebook so you can keep track of the temperatures of each cup – record for 30-second intervals for five minutes.
• Place the five cups side by side in the tray and set on a sturdy works surface. They should all be lined up.
• Place the fan near the table you are working. Note: it needs to be close enough to create wind. Please adjust as you see necessary to create this effect.
• Measure to make sure your fan is 50 cm away from the cups and that it will blow directly over top of the cups – not on them so they blow over.
• Fill the kettle with water and plug in so it can boil.
• Allow the water to boil for 30 seconds.
• Once the kettle has boiled, use a measuring cup and measure 150 mL of boiling water and place in each cup. Note: you may want to have an adult help you here so you do not burn yourself.
• Carefully set a thermometer in each cup.
• Record the temperatures of the water in each cup in your science notebook.
• Start the fan and then quickly, the stopwatch.
• Record your temperature every 30 seconds in your chart.
• Which cup was the best to protect against the windchill?
What is going on?
The temperature of the air in winter is not always a reliable indicator of how cold you may feel when you go outdoors. Wind speed, relative humidity and sunshine also have an effect on the temperature. Often times on the news you will hear them talk of the temperature with the “wind chill.” It is a good idea to listen to this as the wind chill index is the temperature your body feels when the air temperature is combined with the wind speed. The higher the wind speed the faster exposed areas of your body lose heat and the cooler you will feel (just like in this experiment – the water cooled off at different rates depending on what kind of insulator they had). This is why the news will often tell you that “exposed skin” will freeze in just a few minutes if left uncovered when you go outside. Be careful and listen to these warnings as frostbite is no joke!
Wind chill came into play in your experiment. The cups cooled off as the wind from the fan blew over them. Were you able to determine which type of cup was the best insulator? Please let me know so I can keep my coffee hot on these cold winter mornings!
Hmm… perhaps this would be a good science fair project? There is still time to do a great project – especially if you are looking for something to do during your February break!! The Kiwanis Regional Science Fair will be on April 16 for Grades 7-12 and April 23 for Grade 4-6 – virtually of course.
If you have any questions with regards to Science Fair, do not hesitate to call me anytime at Praxis.
Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, www. praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403.527.5365, email: praxis@ praxismh.ca.