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SALT LAKE CITY — And you thought water froze solid at 32 degrees.
Now, University of Utah scientists may have solved one mystery by showing how cold water can get before it absolutely must freeze — 55 degrees below zero Fahrenheit.
That's 87 degrees Fahrenheit colder than what most people consider the freezing point of water.
Research published in the Nov. 24 issue of the journal Nature indicated that super-cooled liquid water must become ice at minus 55 degrees because the molecular structure of water changes physically with each water molecule loosely bonded to four others.
The findings suggest this structural change from liquid to "intermediate ice" explains the mystery of "what determines the temperature at which water is going to freeze," according to Valeria Molinero, assistant professor of chemistry at the University of Utah and senior author of the study.
You need that to predict how much water in the atmosphere is in the liquid state or crystal state. This is important for predictions of global climate.
–- Valeria Molinero, U of U
"We're solving a very old puzzle of what is going on in deeply super-cooled water," she said.
How and at what temperature water must freeze has more than just "gee-whiz" appeal, a University of Utah news release states. Atmospheric scientists studying global warming want to know at what temperatures and rates water freezes and crystallizes into ice.
"You need that to predict how much water in the atmosphere is in the liquid state or crystal state," which relates to how much solar radiation is absorbed by atmospheric water and ice, Molinero said. "This is important for predictions of global climate."
She also noted that the findings could help scientists develop applications for atmospheric chemistry and materials that respond to the changes in the various states of liquid.
Molinero, along with chemistry doctoral student Emily Moore, devised a new computer model that is 200 times faster than its predecessors. The model simplified the number crunching and the findings could be very useful in the future, she said.