What do wine 'legs' or 'tears' mean?
Quick answer
Wine 'legs' or 'tears' are the slow-moving droplets that trickle down the inside of your glass after you swirl it. They are caused by the Marangoni effect — a difference in surface tension between alcohol and water — and mainly indicate alcohol content and residual sugar.
Detailed answer
Swirl your glass, set it down, and watch: thin rivulets will slowly creep down the inside wall. Some people call them 'legs', others call them 'tears', and many assume they signal a high-quality wine. The truth is simpler — and more interesting.
What you are actually seeing is physics in action. Alcohol evaporates faster than water (its boiling point is 78.4 °C versus 100 °C for water). When alcohol escapes from the thin film on the glass wall, the remaining liquid becomes richer in water, which has higher surface tension. That tension pulls the liquid upward into a ring, which eventually breaks into droplets that slide back down. Scientists call this the Marangoni effect.
Thicker, slower legs generally mean higher alcohol or more residual sugar — or both. A full-bodied Zinfandel at 15 % ABV will show much more dramatic legs than a crisp Muscadet at 12 %. Sweet dessert wines like Sauternes, which can contain over 200 g/l of sugar, produce legs so thick they almost look like syrup.
Here is a fun experiment for your next tasting: line up three wines of different alcohol levels and compare their legs side by side. You will notice a clear correlation between ABV on the label and the speed of the tears.
Bottom line: legs tell you about concentration, not about quality. A perfectly made 11 % Riesling with thin legs can be far more exciting than a jammy 15 % red with dramatic ones. Trust your nose and palate instead.