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Showing 5 posts tagged pressure
We were just watching how wind (and so many other things) can get going with the spin of the Earth, now let’s go deeper and find out more about what wind is with PBS’ Dr. Joe Hanson of It’s Okay To Be Smart.
For this experiment, you can use a bicycle pump with a rubber stopper attachment, rubbing alcohol and a clear 1 liter bottle. Don’t forget goggles and some adult supervision! Steve Spangler’s Science has more:
The reason the rubbing alcohol forms a more visible cloud is because alcohol evaporates more quickly than water. Alcohol molecules have weaker bonds than water molecules, so they let go of each other more easily. Since there are more evaporated alcohol molecules in the bottle, there are also more molecules able to condense. This is why you can see the alcohol cloud more clearly than the water cloud.
Clouds on Earth form when warm air rises and its pressure is reduced. The air expands and cools, and clouds form as the temperature drops below the dew point. Invisible particles in the air in the form of pollution, smoke, dust or even tiny particles of dirt help form a nucleus on which the water molecules can attach.
Dr. Roy Lowry of Plymouth University in the UK made science explosively exciting for his class by demonstrating how powerful (and loud) it can be when the pressure of cold, trapped Liquid Nitrogen, a liquified gas, is warmed in a bucket of water. Then he added 1500 Ping Pong Balls.
If that didn’t make sense, watch. He’ll explain it all. And then when you see him pour the balls in and run away (it’s dangerous!), cover your ears or turn down the volume, and let the science commence!
(Updated video link.)