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The phenomenon called tears of wine is manifested as a ring of clear liquid, near the top of a glass of wine, from which droplets continuously form and drop back into the wine. It is most readily observed in a wine which has a high alcohol content. It is also referred to as wine legs, curtains, or church windows. ==Cause== The effect is a consequence of the fact that alcohol has a lower surface tension than water. If alcohol is mixed with water inhomogeneously, a region with a lower concentration of alcohol will pull on the surrounding fluid more strongly than a region with a higher alcohol concentration. The result is that the liquid tends to flow away from regions with higher alcohol concentration. This can be easily and strikingly demonstrated by spreading a thin film of water on a smooth surface and then allowing a drop of alcohol to fall on the center of the film. The liquid will rush out of the region where the drop of alcohol fell. Wine is mostly a mixture of alcohol and water, with dissolved sugars, acids, colourants and flavourants. Where the surface of the wine meets the side of the glass, capillary action makes the liquid climb the side of the glass. As it does so, both alcohol and water evaporate from the rising film, but the alcohol evaporates faster, due to its higher vapor pressure. The resulting decrease in the concentration of alcohol causes the surface tension of the liquid to increase, and this causes more liquid to be drawn up from the bulk of the wine, which has a lower surface tension because of its higher alcohol content. The wine moves up the side of the glass and forms droplets that fall back under their own weight. The phenomenon was first correctly explained by physicist James Thomson,〔James Thomson (1855) ("On certain curious motions observable on the surfaces of wine and other alcoholic liquours," ) ''Philosophical Magazine'', 10 : 330-333.〕 the elder brother of Lord Kelvin, in 1855. It is an instance of what is today called the Marangoni effect〔Carlo Marangoni, "Sull' espansione delle gocce di un liquido gallegianti sulla superficie di altro liquido" (On the expansion of a drop of liquid floating in the surface of another liquid) (Pavia, Italy: Tipographia dei fratelli Fusi, 1865).〕 (or the Gibbs-Marangoni effect): the flow of liquid caused by surface tension gradients. The effect can be used to move water droplets around in technical applications. 〔N.Y. Times, "Tiny Internal Tornadoes Bring Drops to Life" ()〕 It is sometimes claimed incorrectly that wine with "lots of legs" is sweeter or of a better quality. In fact the intensity of this phenomenon depends only on alcohol content, and it can be eliminated completely by covering the wine glass (which stops the evaporation of the alcohol). British physicist C. V. Boys argues〔C.V. Boys, ''Soap Bubbles: Their Colours and Forces Which Mould Them'', 2nd ed., Ch. 2, (1911).〕 that the biblical injunction refers to this effect. Since the "tears of wine" are most noticeable in wine which has a high alcohol content, the author may be suggesting this as a way to identify wines that should be avoided in the interest of sobriety. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Tears of wine」の詳細全文を読む スポンサード リンク
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