I still hope for above freezing snow... read this article to show that there's hope! And it ties two threads together ... now that's an article! "Drunk water, like drunk people, freezes easier"
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Can Testosterone Help Explain How Clouds Form?
For more information on this story contact:
Email Marcia Goodrich <mlgoodri@mtu.edu>
Phone: 906/487-2343
JUNE 6, 2005 -- Your grade school science teacher lied to you.
What's the freezing point of water? If you answered 32 degrees Fahrenheit (or 0 degrees Celsius), you are among the vast, misinformed majority. Will Cantrell, an assistant professor of physics, explains how nearly everyone gets it wrong.
"When I ask, 'How does water freeze?' people look at me crosswise and say, 'That's easy. Just get it cold,'" he says. "But if you take pure water and cool it to 30 degrees Fahrenheit, you'll have liquid water for a long time."
In fact, if you were to suspend a drop of pure water in the air, out of contact with any surface, you'd have to chill it to about minus 35 Celsius, or 37 below zero Fahrenheit, before it would turn to ice. Fortunately for hockey players and purveyors of snow shovels, everyday water is not pure and is almost always touching a surface of some sort. But it does raise an interesting question: Why does water behave so strangely?
"Water is hard to freeze because it's kind of unruly," says Cantrell. "Trying to convince it to organize into a crystal can be really difficult."
On most surfaces, from dust to pavement, water crystallizes into ice with the same predictability that caused us all to miscalculate its freezing point. (The melting point of pure ice--32 degrees F., 0 degrees C.--is virtually immutable.) Cantrell is investigating what properties a surface must have to raise water's freezing point that high.
This would seem a mere theoretical exercise if it didn't hold the key to how cirrus clouds form. These thin, gauzy clouds form miles up in the atmosphere, and while they don't cause thunderstorms they can play a role in the climate by reflecting sunlight and absorbing heat radiating up from the earth's surface.
Cirrus clouds around the equator may be particularly influential. "The tropics are the thermostat for the planet," says Cantrell, who earned his PhD in Atmospheric Science. "The tropics control global climate. And affecting cirrus clouds affects the temperature of the tropics."
Your average cirrus cloud is miles up in the air, so its constituent ice crystals form in the absence of debris such as dust or soot. But suppose such particles found their way up there, through the burning of forests for agriculture or the exhaust from high-flying jets. "As we put more stuff like this into the atmosphere, how will that change the properties of cirrus clouds?" Cantrell asks. "Nobody knows what effects that could have."
They do know that soot raises the freezing point of pure water slightly, from minus 37 to minus 30 degrees Fahrenheit.
But that's nothing compared to the effect the most famous (male) hormone of all, testosterone, has on water.
"With a little testosterone, water will freeze at about minus 1 degree Celsius," Cantrell deadpans. "I am not making this up."
His research focuses on why testosterone and another class of chemicals that Dave Barry would probably like, long-chain alcohols, are so effective in raising the freezing point of water.
"Drunk water, like drunk people, freezes easier," Cantrell notes. "I want to understand how some of these substances are able to convince water to organize into crystals."
"We don't know yet how they do it," Cantrell says. "But we are getting there."
This funny research has a very serious underpinning, which is why Cantrell's work has received support from NASA and the National Science Foundation. The more we understand about the freezing point of water, the more we can learn about how changes in the atmosphere might affect clouds and even global climate.
