High and low pressure are mentioned often in the Storm Team 2 Forecast. Pressure changes based on height and temperature.
Storm Team 2 Meteorologist Carly Smith demonstrates high and low pressure by crushing a can.
Question: How can air cause a can to crush?
Hypothesis: If I change the temperature inside then the pressure will change and the can will crush.
Materials: can, tongs, bowl of ice water, hot plate or stove, and a little bit of water inside the can.
- Turn on your stove or hot plate to a medium or high temperature.
- Fill an empty soda can with a little bit of water.
- Place the can on the stove or hot plate.
- Wait for the water inside to start boiling.
- While waiting for the water to boil inside the can, take a medium to large bowl and fill it with ice water.
- Once the water starts boiling in the can grab the tongs and use them to pick up the can.
- Dunk the can, open end first, into the bowl of ice water.
Observation: The can is suddenly crushed.
Conclusion: When the water inside the can is boiling liquid water molecules are evaporating and water vapor fills the can. The gas wants to fill the entire space, so water vapor and air molecules are pushing out against the edge of the can. Gas molecules move around very quickly. As the temperature rises the pressure in the can is higher.
In the atmosphere air naturally flows away from high pressure. This creates sinking air. Typically with high pressure, we see warmer days with more sunshine.
Once the can is dunked in the bowl of cold water. The temperature quickly changes. The water vapor or gas inside condenses. The water and air molecules slow down. They are no longer pushing on the wall of the can. The pressure drops. The quick change in temperature and pressure results in the rapid crush of the can.
In the atmosphere, air moves away from high pressure and into an area of low pressure. Converging air at the surface will result in rising air. Clouds are able to form as water vapor rises into the atmosphere.
I hope you have as much fun as I did crushing cans! Please share your photos and videos with me on Facebook at Carly Smith WX WDTN.