MANHATTAN, Kan. – Mary Knapp is asked a lot of weather-related questions in her role as the state climatologist for Kansas. One of the questions that comes up at this time of year, in particular, is “What is the frost line and why is it important?”

“In our region, ‘frost line’ generally refers to the depth to which the ground or the water in the ground, will freeze,” said Knapp, who heads the Kansas Weather Data Library, based in Kansas State University Research and Extension. “The frost line will vary from season to season. It depends on air temperature, soil type, the amount of moisture in the soil, the vegetative or snow cover, and such heat reservoirs as asphalt or buildings.”

Knapp said the frost line is primarily of interest in construction. Many building codes, for example, specify that utilities be buried below the frost line.

“In Arctic regions, the more common reference is to the ‘thaw depth’ -- the distance to the permafrost,” she added. “In tropical regions, ‘frost line’ more commonly refers to an elevation below which frost won't occur.”

Information about Kansas weather is available on the Weather Data Library Web site: http://www.ksre.ksu.edu/wdl/. “Weather Wonders” audio reports are available on the K-State Research and Extension News Media Web site at http://www.ksre.ksu.edu/news/. 

-30-