Make Rain Clouds in a Bottle

Done right, this experiment has the most rewarding whoosh.

Follow these steps to make rain clouds in a bottle!

WHAT'S HAPPENING?

You’re mimicking the part of Earth’s water cycle in which evaporated water (water vapor) cools and condenses, forming clouds as they connect with dust. In this experiment, the alcohol acts like the dust, providing something cool for water droplets to attach to.

When you pressurize the soda bottle by pumping air in, the air molecules collide with each other and warm the bottle. Releasing the pressure causes the water vapor to condense quickly, forming a cloud.

WHAT TO EXPECT

Once the pressure is released—either because the cork blows or the needle is removed—a cloud should form quickly and dramatically in the bottle. Note: Aim the bottle away from you and anyone else.

GLITCH?

No cloud? Your seal isn’t tight enough. Try a different cork, or use duct tape to tighten the seal.

BONUS: REVERSE THE EXPERIMENT!

Before the cloud disappears, put the needle back in and pump a couple more times. The cloud should disappear as quickly as it came. Release the pressure, and the cloud will reform.