My opening presentation was a lot of fun for this topic. We talked about mythology (all of the cultures that had a god representing wind, e.g., the Greek god Aeolus). We talked about world record wind speeds – the record originally belonged to Mt. Washington with a recorded wind speed of 231 miles per hour, but as of 1996 the record belongs to Barrow Island Australia with a recorded surface wind speed of 253 miles per hour! We even talked briefly about the daring kite fighting events in countries like Brazil, Afghanistan, India, and Pakistan where kite strings are coated with powdered glass and people battle to take down other kites!
My group also had a lot of laughs over this hilarious video of people in Norway trying to cross a street as Storm Ivan hits. At one point, you can even see how the police have to start escorting elderly people across the street because they literally can’t walk across on their own! 🙂
Thanks to our “visit” with Bill Nye the Science Guy via his episode on Wind, we also got a very good explanation for not only how winds are created, but also how other weather phenomena occur…like hail storms. With Bill Nye’s parting wisdom, we were ready to launch into our two main experiments of the day: Windbags and Anemometers.
Experiment #1: Windbags
- I purchased packs of “wind bags” from the Steve Spangler web site because that was simplest, but you can actually create your own windbags using the cartridges that come from diaper genies and the like; you should ideally have 1 bag per scientist
Our experiment was really very simple. Each windbag needs to be knotted closed at one end (I did this in advance so my scientists wouldn’t have to worry about that detail). For my first demonstration to the group, I pinched the open end mostly closed and asked them how much air they thought I could trap in the windbag with 3 large breaths by putting my mouth right up to the opening. After my 3 breaths, I fully closed the open end and dragged my hand down the length of the windbag until I had gathered my air at one end (I only gathered about 1-2 feet of air in the bag). My second attempt created a perfect launching pad for explaining the Bernoulli Principle to the group. Holding the open end of the windbag wide open, keeping my mouth back from the opening about 6 inches, and doing just one giant breath, I was able to trap significantly more air in the windbag! Why did this happen? When I blew into the windbag, it created an area of lower air pressure inside the bag than outside it. Bernoulli’s Principle suggests that the atmosphere wants to remain balanced, so air from the outside of the bag actually races into the bag alongside my breath to help stabilize the pressure and make it match the pressure outside the bag. My scientists had a blast testing this out time and again (and, of course, jousting with the full windbags when they were finished) 🙂
Experiment #2: Anemometers
- Paper cups (I used dixie cups, but you can also create this using regular sized cups); you will need 5 cups per scientist
- Pencils (1 per scientist)
- Pushpins (1 per scientist)
- Plastic straws (2 per scientist; you can use either bendy or straight straws, whatever you have on hand)
- Scotch tape
- Sticker dots or magic markers (you need to mark the base of one of the outer cups so you have a way to visually count revolutions – you can use markers, but I had some colored sticker dots handy and used them instead)
- Single-hole paper punch or scissors
While this project was fairly easy to assemble, there are a few temperamental steps along the way where my scientists needed an extra hand. Before my program, I did a little preparation in advance. Each scientist will receive 5 paper cups. Four of those cups will need 2 holes about a half inch to an inch below the lip. You can use scissors to punch the holes, but I used my handy single-hole paper punch to pop them in. [I marked the cup lips lightly with pencil to help guide my use of the paper punch.] The fifth cup will need 4 holes evenly spaced around the cup, also a half inch to an inch below the lip. And in this fifth cup you may want to also punch a hole in the center of the bottom of the cup in advance (I forgot to do this and several of my scientists had trouble doing this on their own). I won’t go into detail about all of the steps here because there are two great sites that give detailed explanations:
- This instructables.com post had some excellent step-by-step photos for creating a simple paper cup anemometer
- I liked this Southeast Regional Climate Center PDF for its descriptions on the various steps, and in particular, I liked the table at the end of the PDF that gives you a translation for “revolutions in seconds” to both “miles per hour” AND “kilometers per hour” for the actual wind speed you’re recording
There are lots of sites that give similar though differing instructions for how to create simple anemometers – the two above sites were my favorites.
One of the steps that gave my scientists some trouble was positioning the 4 outer cups on the straws. The tricky parts were 1) using the scotch tape to make sure the cups remained in a sideways position, and 2) making sure that all cups were pointed in the correct direction and were optimized for capturing wind. You also need to make sure that in the final step, when the pushpin is pushed through the crossing straws into the pencil eraser, the pin is loose enough in the eraser that the cups can freely spin when they encounter wind.
Since going outside to test the anemometers with real wind wasn’t going to be an option for me, I brought in my hair dryer from home and let the kids take turns. On the plus side, the kids enjoyed seeing the anemometers successfully rotating and moving with the air. On the negative side, the blow dryer wind was too strong to allow for doing actual readings with our anemometers. It worked better the further back I stepped from the scientists, but it still wasn’t ideal for doing actual recordings. Perhaps a fan would generate a gentle enough wind for real-time tests of the anemometers…
This was the final program in this current session, but look for more fun from Gizmos, Gadgets and Goo when my scientists and I return to our experiments in November and December. In the meantime, check out the fun video of our “wind” activities below… 🙂