You ever crack a cold one (soda, beer, champagne) and witness a little cloud linger near the mouth of the drink? That cloud's there because of adiabatic expansion, baby. Expansion without any heat exchanged with the surroundings: that's thermodynamics at play.
Carbonation
Carbonated drinks have additional CO2 dissolved in the liquid that makes them fizz, that's been added through different methods. For soda, injecting CO2 under pressure forces the gas to stay dissolved in the liquid at the bottling plant. For certain alcoholic drinks like beer and champagne, the CO2 comes from fermentation: yeast cells eat sugar and produce alcohol + CO2 as byproducts (alcohol is microbe poop!).
The bottle/can stays sealed holding pressure and keeping the gas trapped in solution but when you open it, the pressure drops (to atmospheric pressure), the CO2 comes out of solution and you get bubbles and fizz. Think of shaking up a coke bottle, nothing happens until you actually twist the lid enough to crack then it'll all come crashing out.
When you open it, oftentimes you'll see a little cloud form, especially in bottles. What's happening here? That little cloud isn't CO2: CO2 gas is colorless and invisible. That cloud is made of water vapor condensing into tiny tiny droplets (basically a mini-cloud).
Adiabatic Expansion
Molecules are all bouncing around with a certain amount of energy, which we measure as temperature. Higher temperature = more energy, the particles are bouncing around a lot more, and faster. Lower temperature = less energy. Think about gas molecules in a compressed space like a bunch of bouncy balls bouncing around with a certain amount of energy. If you suddenly give them more room, they spread out and this work costs energy.
For the case of the carbonated drink, when you open up the drink and open the compressed CO2 to the atmosphere, it expands to spread out and does work pushing against the surrounding air. This work costs energy, and since there's no heat coming in from anywhere outside (the process is so fast, there's no time for any heat to transfer), the energy needs to come from the gas itself and its temperature drops. This is a pretty dramatic drop too, research in the journal Physics of Fluids shows that in that jolt of expansion, temperatures can cool down to anywhere from -50ºC to -70ºC (Antarctica in the wintertime, but in a super small volume).
This is the same process that causes clouds to form but in a much smaller (and faster, more violent) scale. That sudden cooling drops the air temperature below its dew point, the point at which water vapor in and around the escaping gas can't stay gaseous, and so condenses into a visible mist. The thermodynamic work is all done by the CO2, but what we see is the condensed water vapor.
References and Additional Reading
- On the popping sound and liquid sloshing when opening a beer bottle — Physics of Fluids, 2025
- Vapour pressure and adiabatic cooling from champagne: Slow-motion visualization of gas thermodynamics — Physics Education, 2012