Cloud in a bottle



Making your own small clouds with a hard squeeze: A plastic bottle, a bit of water, and a match will lead you to appreciate how some clouds form. If you have a thermocouple thermometer, you can dig a bit further. Here’s the link for the full story.

Cloud in a bottle: This is a simple demonstration of phenomena in forming clouds in nature.

Equipment: minimal, cheap.

You fill a clear, squeezable bottle with saturated vapor – you do that by putting a little water in the bottom of the bottle and shaking and swirling it around for, oh, say, a minute. Next, you light a match and put it in the mouth of the bottle and shake it to extinguish the flame and introduce smoke into the bottle, then quickly capping it. If you feel safer, you might light a longer piece of wood, or a cork punk. Now squeeze the bottle hard and then release it sharply. The interior will fill with mist, which is tiny water droplets that condensed around the tinier smoke particles. You can keep squeezing and then releasing the bottle several times to get the effect.

The principle is that the sudden expansion of the air in the bottle decreases its temperature to the point that it is below the condensation point of the water vapor. To put it technically, the expansion is adiabatic, without exchanging any significant heat with the outside air. There are several discussions of the temperature effect, which also explains the decrease of temperature as air goes to higher elevations in steady (nonturbulent) conditions; my explanation using the physics is on another post in these webpages. Of course, the squeezing is the opposite effect. To make the demo more detailed, you can run a fine-wire thermocouple thermometer into the bottle through a tiny hole in the lid, sealing it thoroughly. You can run the thermocouple end to a thermocouple thermometer as I’ve done in this picture. You’ll see the temperature rise on squeezing the bottle and fall on letting it expand.


Video for frames to grab – filling it with a bit of water, shaking it, lighting a match, putting it out to make smoke, sealing the bottle, squeezing it, releasing it, and doing it again

Picture of a cap with a hole

Picture of Omega TCT with lead and with reading

Picture of TC threaded into hole and sealed

Video of squeezing while viewing the TCT and the bottle contents


Leave a Reply

Your email address will not be published. Required fields are marked *

WordPress Anti-Spam by WP-SpamShield