Step-by-step tutorial
Step 1
Gather your materials.
Step 2
Pour a small amount (roughly 1 tablespoon) of rubbing alcohol into your empty bottle and screw the cap back on.
Step 3
Swish the rubbing alcohol around so that it covers the walls on the inside of the bottle.
Step 4
Use the pushpin to poke a hole in the middle of your cap. Widen the hole with your pencil so it's just large enough to fit the needle of your pump.
Step 5
Slide the needle of your pump into the hole, and add some clay to the inside of the cap. Squeeze the bottle to make sure it's air-tight.
Step 6
Pump up the bottle! The more you pump, the more dramatic your result will be! We pumped about 40 times. Just make sure to keep the bottle air-tight.
Step 7
When you're done pumping, hold onto the bottle firmly and twist open the cap to release the pressure. (A loud popping noise will occur, so any onlookers around may want to plug their ears.) A cloud will instantly form inside!
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So what's happening?
When you release the pressure, the gas inside rapidly expands. This expansion causes the rubbing alcohol vapor inside your bottle to cool off very quickly and condense into little tiny droplets. These droplets are your cloud!Extra experiment! Try twisting your cap back on with the cloud still inside. Then re-pressurize your bottle by pumping. What happens to your cloud?