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Jan 8, 2008 5:19 pm US/Pacific
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Good Question: Does Blowing On Soup Help Cool It?
SACRAMENTO (CBS13) ―
I was taught when I was a little kid that blowing on soup really cools it off but now I'm wondering, is that an old wives' tale?
"It's really true, blowing on soup really does cool it off and the reason is that when you blow on it, you cause more evaporation and the more evaporation, the faster the soup cools," explain s Dr. Ralph Aldredge, a professor at U.C. Davis.
Dr. Ralph Aldredge, with the U.C Davis engineering department explains how this works. Saying soup is mainly water and as it evaporates it becomes a vapor that sits on the surface of the soup and when you blow on it, it pushes the vapor away, sending away some heat and allowing more room for more heat to escape.
We wanted to know how fast it happens. So we thought we'd conduct our own experiment. We're going to take this soup which is about a hundred thirty degrees - pour some of it in this bowl and let it cool off on its own, then pour some in this bowl, and let the fan simulate blowing."
And sure enough, the bowl that cooled on its own only went down to about one hundred ten degrees, but the bowl with the fan blowing over it got down to about ninety.
So there you go, we just proved a little airflow makes a big difference!
Very informal experiment - but you get the picture and if you blow just on the spoon- it cools even faster!
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