10-04-2017, 09:14 PM
Atmospheric Radiation
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Introduction
The major source of earth is the sun.
The sun transfer energy through the earth by radiated
electromagnetic wave.
In vacuum, electromagnetic waves travel at speed of light (300,000
km/s).
The continuous electromagnetic spectrum distinguishes different
types of waves based on wavelength and frequency.
Heat Transport in Atmosphere
Transport of heat is accomplished by conduction,
convection and radiation
radiation: energy transfer which can take place in a vacuum, with
no intervening physical medium (unlike conduction and
convection)
conduction: transfer of kinetic energy of molecules by collisions
of molecules
convection: transport of heat within a fluid by bulk motion of fluid
itself
heat transported by conduction and convection is
"sensible heating"
Basic Concepts
The subject of atmospheric radiation is concern with the transfer
energy within the atmosphere by photons, or equivalently by
electromagnetic wave.
Solar radiation
solar radiation is emitted from solar
photosphere (surface of sun), at a
temperature of 5800 K
it is most intense at a wavelength of
about 0.5 microns (micrometer), which
lies in the visible part of the
electromagnetic spectrum