Water and Energy Balance
Evapotranspiration: the sum of surface evaporation and transpiration
Transpiration: the loss of water from plant leaves
Water vapor feedback: greenhouse effect provided by water vapor, when the atmosphere warms and increases its water vapor content
Net radiation: balance between the inputs and outputs of shortwave and longwave radiation
Direct radiation: radiation that comes directly from the sun without scattering or reradiation by the atmosphere or objects in the environment
Diffuse radiation: shortwave radiation that is scattered by particles and gases in the atmosphere
Reflected radiation: shortwave radiation that is reflected from clouds and objects in the landscape
Albedo: fraction of the incident shortwave radiation reflected from a surface
Snow/Ice albedo feedback: atmospheric warming caused by warming-induced decrease in albedo due to earlier snowmelt
Emissivity: coefficient that describes the max rate at which a body emits radiation, relative to a perfect (black body) radiator, which has a value of 1.0
Ground heat flux: heat transferred from the surface into the soil
Latent heat of vaporization: energy required to change a gram of a substance from a liquid to a vapor without change in temperature
Turbulence: irregular velocities of air or water movement that can transport heat and materials more readily than by diffusion
Bulk air: air above the canopy that isn’t strongly influenced by the canopy.
Convective turbulence: caused by the increased buoyancy of surface air caused by heat transfer from the surface.
Mechanical turbulence: caused by the uneven slowing of air by a rough surface.
Roughness element: obstacle to air flow (i.e. a tree) that creates mechanical turbulence
Bowen ratio: ratio of sensible to latent heat flux
Specific heat: energy required to warm a gram of a substance by 1C
Vapor pressure: Partial pressure exerted by water molecules in the air