Beer Bottle Condensation: What Forces Produce Droplets?

philosophy, Physics
Dan asked us¹... "My question concerns condensation droplets. What dictates how droplets form, then combine with each other? When you blow warm breath onto a cool surface, at first nothing appears to happen. Keep it up and droplets appear. These small droplets merge into bigger droplets. What physical laws dictate how this occurs? Also, what role does gravity play on vertical surfaces such as a chilled bottle of beer, producing tiny rivulets of moisture running down the sides?" Initial Commentary The answer, which follows, although it has some basis in well-known physical principles, depends in part upon observation, mental visualization, and (finally) blatant speculation. This is an interesting procedure, since so many of life’s mundane occurrences are in reality quite fascinating when closely examined. Initial Condensation We breathe in and…
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Capillary Action from the Forces of Adhesion and Cohesion

Chemistry, Plants
What is capillary action? The easiest way to define it is to give the simplest example of it at work. A capillary is a tube with a fine bore, typically less than a millimeter. For the purpose of our discussion, we will use a scientist's glass capillary tube, which is both straight and clear. The liquids we will discuss as examples are water and mercury. Not All Liquids Exhibit Capillary Action Take note of Figure 1. Two capillary tubes (not drawn to scale) are immersed in liquid – the left tube in water, the right in mercury. The water rises up its tube and forms a concave meniscus at top. The mercury does not rise up its tube. It forms what looks like the upper portion of a sphere –…
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