Reported November 2008

What is Freeze-Pruf?: Freeze-Pruf combines five ingredients into one liquid spray to protect against cold damage in plants. The ingredients have a synergistic effect that exceeds the sum of what they would do individually. The ingredients include an antifreeze-like substance that is present in animals, another that helps lower the freezing point of plant cells by dehydrating them, one that strengthens cell walls, another that helps the solution penetrate leaves and one to resist washing away by rain and snow. The protection lasts about four to six weeks, and the best times to use it are the in late fall and early spring.

What is Frost, and How does it Form?: Tiny frozen water droplets in the air make frost. Water changes to ice in a process known as a phase transition. When water reaches freezing temperature it will turn into ice. Different materials freeze at different temperatures, but water at sea level will freeze at 32 degrees Fahrenheit. Humidity measures how much vapor is present in the air at any given time. Clear, calm, fall nights when the air mass is especially humid are the best conditions for frost to form.

Frost is the frozen version of dew. Like snow, it results from the presence of too much water vapor in already saturated air. It is a very thin deposit of tiny ice crystals. Frost forms when water vapor in the air condenses directly into ice instead of condensing first into a liquid, then into ice. Condensation typically occurs when the temperature drops sufficiently and the air becomes saturated with water vapor. The excess vapor condenses onto surfaces colder than the air. If the surface temperature is above 32 degrees Fahrenheit, dew will form; if it is below 32 degrees Fahrenheit, frost will form. Frost forms on the inside surface of windowpanes when the air inside has lower humidity than the air outside. If it didn't, the water vapor would first condense into small drops before freezing into clear ice.

If you would like more information, please contact:

David Francko, Ph.D.
Tuscaloosa, AL 35487
(205) 348-8280
dfrancko@ua.edu