You hear it all the time. “Look at the legs” as they hold their glasses in the air and twirl them around looking at the tear drops rolling down the bowl. Many people, consciously or subconsciously, equate a wine’s legs to a wine’s quality. This is mistake. While a wine with great legs might be a phenomenal wine, it could also be plonk.
Some people swear that a wines legs are an indicator of quality when in reality, wine legs are simply science at work. Wine legs are an example of a scientific phenomenon known as the Gibbs-Marangoni Effect where there is fluid surface tension caused by the evaporation of alcohol. When you swirl your glass, the wine coats the glass and some of the alcohol begins to evaporate. As this happens, the wine collects on the sides of the glass and starts to form the tear like droplets that you recognize.
Having said this, wine legs can tell you at least one thing about a wine. Since wine legs don’t appear without the evaporation of alcohol, wine legs can be an indicator of the alcohol content in a wine. Higher alcohol wines will have more legs. So, the next time someone tries to tell you that you’re sipping fine wine because the wine has great legs, you’ll know better.