Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Soil Moisture Content
Name: Peter d'E.
Status: other
Age: 50s
Location: N/A
Country: N/A
Date: 2001


Question:
How does moisture content in soil affect the soil temperature?


Replies:
Peter,

Water has a very different thermal conductivity than most soil particles and air (the thermal properties of the soil are determined by these three). The thermal conductivity of water is much greater than that of air, so the higher the soil moisture content the greater the thermal conductivity.

The greater the soil moisture content, the more the soil thermal conductivity is like that of water. Therefore, a saturated soil has a conductivity near that of water.

However, just because the soil moisture content is high, doesn't mean that the soil will warm up faster in the Sun than a dry soil. Evaporation of the water will remove much of the Sun's energy before the soil will have a chance to warm.

Therefore, dry soils do warm up faster from sunlight and cool faster at night. This is assuming that there isn't a vegetation cover over the soil. Most wet soils evaporate the water, keeping the soil from warming as fast during the day, and cool more slowly at night because of their greater heat capacity (because of the higher water content).

Soils that are better at holding water in them (reducing evaporation), such as clays and peat, are the exception to the above; they may not evaporate as much water and therefore do heat up in the sun, and do not loose as much energy at night. Peat bogs are often very warm, although part of that energy comes from rapidly occurring rotting of organic matter. Wet clays can also become very warm in the Sun.

David R. Cook
Atmospheric Research Section
Environmental Research Division
Argonne National Laboratory


Click here to return to the Weather Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory