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Summary:
Some air masses on Earth are warm, wet, and have a low density. We call them “low pressure systems.” On the other hand, some air masses are colder, dryer, and heavier. We call these “high pressure systems.” So what happens when the two meet? That’s where it gets interesting. Usually, the heavier air will slide beneath the warmer, wetter air. And when warm, wet air is pushed skyward, it cools off. The water vapor then condenses, forming clouds of droplets. And if those droplets get heavy enough… grab your umbrella. Unfortunately, this process is hard to simulate in the lab. Condensation requires large temperature changes, which take time. And unless you want a foggy classroom, we can’t use regular air either. Luckily, both of these problems can be solved with a plastic bottle and a regular old bicycle pump.

Resources:
April 5 – Cloud in a Bottle Lab (pg612).docx