Hi this is Dave Thurlow for the Weather Notebook. Today on the show we answer one of our Weather NotebookTwisters.
A few weeks ago we asked how bubbles in your coffee might forecast the weather. The theory that some swear by is that during dry sunny weather bubbles will congregate in the middle of the cup and during cloudy damp weather bubbles will cling to the sides of the cup.
Well, as with many weather folktales, the science behind it may make sense but the actual observations don't always reveal the connection to the weather. Listener L.A. Garcia of Yuma, Arizona pointed out to us that he has no doubt that the position of the bubbles in a cup of coffee has no weather forecasting value whatsoever, and he's got a point. However the discussion has some educational value, as he also pointed out. Many listeners theorized that the humidity in the air was the culprit that shifted the coffee bubbles day to day. Some though, including Jim Murray of Pine Meadows, Connecticut and Edith Bently of Fort Thomas, Kentucky suggested that air pressure would be the cause.
High air pressure during fair weather will make the surface of the coffee slightly concave so that the bubbles will slide into the middle of the cup. On the other hand low air pressure during foul weather will make the surface of the coffee slightly convex and the bubbles will slide down to, and stick to the cup. The theory is pretty reasonable but as several listeners said it's hard to think straight until after the cup of coffee - then it's too late to make any observation. So now you know that all those people you see staring into their coffee are aspiring meteorologists.
The Weather Notebook is made possible by a grant from The National Science Foundation. Additional support comes from Subaru, maker of the all weather Legacy. Subaru, the beauty of all wheel drive.