Lecture 7: Soil Aeration and Temperature Flashcards
Explain the greenhouse effect
-heat resulting from the absorption of incoming shortwave radiation is emitted as longwave radiation by surfaces and greenhouse gases
-the land surface emits longwave radiation and receives longwave radiation from greenhouse gases and other surface
Write the land surface energy balance
Rn=G+H+lamdaE
Net radiation=Ground heat flux+Sensible heat flux+Latent heat flux
What is net radiation
how much energy in terms of radiative energy an ecosystem has available to do things
What is albedo
the reflectivity of a surface
-ranges from 0.1 (dark and rough) to 0.5 (light and smooth)
-snow covered soils can have an albedo of almost 1
-moisture and live vegetation darkens the surface so lower albedo
What is ground heat flux
Temperature difference between the surface soil and the subsoil. A type of conduction
-larger temperature gradient between the surface and the depth the stronger the flux will be
-the shorter the distance is the higher the flux will be
-the higher the thermal conductivity is the higher the flux will be
What is sensible heat flux
only small amount of energy used for this. this is heat energy that you can feel like for photosynthesis and other processes
-higher is dryer hotter areas
What is latent heat flux
most of the energy that reaches an ecosystem is used to convert water into water vapor (evapotranspiration)
What is heat capacity
the rate at which soils change temperature is described by their heat capacity (specific heat)
-amount of energy required to raise the temperature of soil by 1 degree celsius
-dry soils have a lower heat capacity than wet soils (dry soils warm up faster than wet soils)
What is thermal conductivity
Transfer of energy from molecule to molecule through direct contact
How are heat capacity and thermal conductivity affected by soil moisture, porosity, and/or surface covers
The closer molecules are, the faster they can conduct heat. Thermal conductivity also higher in areas where the soil is wet because the water is connecting the soil particles
-soils with organic cover has less temperature changes because it stays cool but also resistant to high increases of temperature
What temperature critically affects the quality of soils as habitats for plants and microorganisms?
Soil
What is frost heave
water infiltrates deeper parts, created an ice lance, and collapses
What is cryoturbation
results in patterned ground. polygons, nets, frost boils
What is patterned ground
form of nature self organizing. depends on slope of land and size of rocks and texture of rocks
-comes from seasonal thaw and freezing
Explain how fire affects soil properties
-Volatizes hydrocarbons that solidify/condense to form hydrophobic surface, hence low infiltration rates
-plants and seeds die so the fire removes competition
-seeds may germinate
-organic layers combust exposing mineral soil
-ash is nutrient rich
