Heat-Its Role in Wildland Fire. Clive M. Countryman

Heat-Its Role in Wildland Fire - Clive M. Countryman


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       Clive M. Countryman

      Heat-Its Role in Wildland Fire

      Published by Good Press, 2020

       [email protected]

      EAN 4064066424749

       The Nature of Heat

       The science of heat is relatively new

       Heat is energy

       The joule is the standard unit of heat

       Molecular structure affects temperature change

       Heat capacity varies with density and specific heat

       Much energy is involved in changes of state

       Heat transfer is needed for a fire to burn and spread

       Summary

       Heat Conduction

       Conduction is the transfer of heat by molecular activity

       Heat conduction and fluid flow are alike

       Temperature gradient affects conduction rate

       Quantity of heat conducted varies with area

       Fuel density affects thermal conductivity

       Summary

       Heat conduction and wildland fire

       Heat conduction and combustion

       Wildland fuels do not burn directly

       Burning wood has four zones

       The combustion process

       Ignition depends on temperature and heat quantity

       Ignition and combustion take longer in dense fuels

       Moisture affects pyrolysis and ignition

       Char slows pyrolysis

       Heat Conduction and Fire Control

       Small fuels are most important

       To stop the fire, stop pyrolysis

       Summary

       Radiation

       Radiation is energy in the form of electromagnetic waves

       Radiation varies in wavelength

       Radiation intensity and wavelength change with temperature

       Radiation intensity changes with distance and angle

       Substances differ in ability to emit and absorb radiation

       Not all thermal radiation is absorbed

       Some radiation is reflected

       Substances tend to attain a common temperature

       Summary

       Radiation and wildland fire

       Radiation and Weather

       Heat reaches the earth through radiation

       Surface and air temperatures follow radiation intensity

       Variation in radiative heating controls weather

       Radiation and Fuels

       Radiation helps create fuels

       Radiation intensity affects fuel moisture

       Radiation and fire behavior

       Fire is a high-temperature heat source

       Radiation influences fire spread


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