The carbonation in beer can be a confusing concept for some people. After all, if you open up a bottle of beer and pour it into your glass, it doesn't stay bubbly forever. So why does the foam go flat after just a few minutes? There are many factors at play when it comes to beer in a glass. The bubbles are released from the surface of nucleation sites like imperfections in the inside of the glass, grains of salt, and dust particles. A potter can create glasses with variations in the thickness of the glass, indentations or special surfacing on the bottom to affect how much nucleation occurs. The temperature of your glass: tavern or home will affect how much nucleation occurs as well because cooler temperatures mean less gas dissolved in liquid so less gas available escape through nucleation."
The first is the fact that beer is made up of carbon dioxide, alcohol and water. When you pour your beer into the glass, some of the carbon dioxide gas will come out of solution as bubbles. This causes foaming on top of the drink. The amount that comes out depends on how long you let it sit before drinking and other factors such as temperature (which affects solubility).
These are called nucleation sites. When you shake your beer before pouring it into a glass, you're helping to create more nucleation sites for CO2 to release from.
The glassware industry has responded to the popularity of craft beer by creating innovations in glassware that allow for varying levels of nucleation. For example, a potter can create glasses with variations in the thickness of the glass, indentations, or special surfacing on the bottom to affect how much nucleation occurs. Some glasses have dimples or textured bottoms that cause bubbles to form more readily than other kinds of glasses. It's important for customers to know what style of beer they are drinking so that they can select appropriate glassware for maximum enjoyment!
As the liquid warms up, more CO2 is released from nucleation sites on the inside of the glass (let's call them "gassy bubbles"). Cooler temperatures mean less gas dissolved in the liquid, so there won't be as many bubbles available to form under normal circumstances.
If you've ever noticed a beer getting warmer and bubblier over time at a bar or during a party, chances are it's because people aren't drinking fast enough for their drinks to stay cold enough for long periods of time—meaning there's more carbon dioxide available for bubbles to form at any given moment.
There are two main reasons why your beer keeps bubbling once it's in a beer glass. The first is that cooler temperatures mean less gas dissolved in the liquid and so less gas is available to escape through nucleation. As you pour the beer into your glass, more of it comes into contact with air bubbles and those air bubbles are able to form even faster because there’s more surface area for them to form on.
The yeast is at its most active when it's first introduced to your beer, so you may notice that bottled beers are bubblier when you first open them. But once they've been stored for some time, there's more space between the liquid and gas, which means less bubbling—and we can only conclude that this is simply because an unopened bottle of homebrewed ale contains more carbon dioxide than one that's been open for weeks on end.
The bubbles in your beer are carbon dioxide. The gas is dissolved at the bottom of your glass, and as you drink it up, more CO2 comes out of solution and forms tiny bubbles that make up foam on top.
When you pour beer into a glass, there are imperfections in the glass—little pits called nucleation sites—that act as tiny bubble makers. These nucleation sites can be caused by scratches or chips on its surface, sand from drilling machines used to make bottles and barrels (and other things), small grains of salt or dust particles clinging to it after being washed with water or put through dishwashers; basically anything that creates a rough spot on what otherwise would be a very smooth surface.
The next time you're enjoying a nice cold beer, think about the science behind what's happening! The bubbles in your glass are helping to release carbon dioxide from nucleation sites on the surface of your glass. This is why you should always swirl your glass and never shake it because shaking will create more nucleation sites and make more CO2 escape from inside.