quiz 1 cont'd Flashcards
a blackbody is…
… a perfect radiator and absorber at a given temperature
it will absorb all radiation that strikes it and will radiate the maximu amount of energy that a medium at its temperature is capable of radiating
does not exist but some materials come close.
e.g. snow in the infrared
Stefan-Boltzmann Law
The total emitted radiation from a blackbody is proportional to the fourth power of its absolute temperature
As the temperature of an object increases, its dominant wavelength…
…shifts toward the shorter wavelengths in the spectrum
total radiant energy exiting an object is the sum…
of the area under each radiation curve
a micrometer is…
one millianth of a meter
the produces _______ % of its energy in the visible spectrum
41%
the visible spectrum is from about ____ um to about ____ um wavelength
0.4 to 0.7
the order of the three visible light bands starting from shorts to longest
blue, green, red
percentages of suns spectrum in shorter than blue, from blue to red, and from red to longest
9%, 41%, 50%
most remote sensing relies on reflected radiation within
.4 to 2.5 um
Absortptivity
(a): the fraction of incident radiation at a given wavelength that is absorbed by a material
Emissivity (epsilon)
(epsilon): the fraction of blackbody emission at a given wavelength emitted by a surface
Reflectivity
(r): the fraction of incident radiation at a given wavelength reflected by a surfice
Transmissivity
(t): the fraction of incident radiation at a given wavelength tranmitted by a surfice
Kirchhoff’s law:
a + r + t = 1
radiant flux
the time rate of flow of energy onto, off of, or through a surface is called radiant flux and is measured in watts
how electromagnetic radiation is affected in atmosphere
speed, wavelength, intensity, spectral distribution, and direction
scattering differs from relection in that it is …
unpredictable
the amount of scattering (in Rayleigh scattering?) is _____ related to the ______ power of the radiation’s wavelength. Fore example blue light (.4 um) is scattered 16 times more than near-infared light (0.8 um).
inversely; 4th
Rayleigh scattering occurs when …
the diamter of the matter (usually air) are many times smaller than the wavelength of the incident electromagnetic radiation.
