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electromagnetic radiation
as a self-propogating elecctric and magnetic wave that is similar to a wave that moves on the surface of a pond
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wavelength
the wave consists of a series of crests and troughs. the distance between two adjacent crests
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frequency
- greek letter a (lambda). an observer standing at a fixed point in the path of the wave would be passed by a given number of crests in one second. this number is called the frequency of the wave
- v (nu) greek letter
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photon
a single particle or pulse, of electromagnetic radiation is referred to as a photon.
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electromagnetic spectrum
the full range of forms of electromagnetic radiation, which differ by their wavelengths (or by their frequencies), makes up the e.p.
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visible radiation
or visible light, consists of a relatively narrow range of wavelengths, from about 400nm to 700nm.
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visible spectrum
the coloros of the rainbow--in other words, the range of component wavelengths of visible light--are referred to as the visible spectrum
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infrared radiation
are significantly longer than those of visible light. hence, it is convenient to keep track of them in units called micrometers (um) rather than in nanometers.
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ultraviolet (UV) radiation
- about 10% of the Sun's energy is emitted at wavelengths shorter than those of visislbe light
- wavelengths of the ultraviolet region extend from 400nm down to about 10nm
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flux
is the amount of energy (or number of photons) in an eletromagnetic wave that passes perpendicularly through a unit surface area per unit time
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inverse-square law
- is expressed mathematically as
- S= S 0 (r0 / r ) ^2
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kelvin (absolute) temperature scale
- measured in units called kelvins (K)
- Scientists, particularly those studying climate, often use this system
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black body radiation
the radiation emitted by a blackbody
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wien's law
- states that the flux of radiation emittted by a blackbody reaches its peak value at a wavelength amax that depends inversely on the body's aboslute temperature
- according to this rule, hotter bodies emit radiation at shorter wavelengths than do colder bodies
- amax (=approx) is the wavelength of maximum radiation flux in micrometers
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photosphere
the sun emits most of its energy, including visible radiation, from the surface layer, and photosphere
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stefan boltzmann law
states that the energy flux emitted by a blackbody is related to the fourth power of the body's absolute temperature
f =ot4
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effective radiating temperature
we do this by defining a quantity Te that represents the ert of the planet. this temperature is the temperature that a true blackbody would need to have to radiate the same amount of energy that Earth radiates
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barometric law
the decrease with altitude follows the barometric law, which states that atmospheric pressure decreases by about a factor of 10 for every 16km increase in altitude
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troposphere
which extends from the surface up to 10 to 15km (higher in the tropics, lower near the poles)
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stratosphere
immediately above the troposphere is the stratosphere, which is located from about 10 to 15km to 50 km above the surface and in which temperature increases with altitude
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mesosphere
above the stratosphere, temperature decreases with altitude in the mesosphere (from about 50km to 90km) and then increases once again in the uppermost layer, the thermosphere (above about 90km)
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convection
is a process in which heat energy is transported by the motions of fluid (a liquid or a gas).
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latent heat
is the heat energy released or absorbed during the transition from one phase--gaseous, liquid or solid--to another
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radiation
is the transfer of heat energy in the form of electromagnetic waves
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conduction
is the transfer of heat energy by direct contact between individual molecules
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H2O rotation band
The frequency (or wavelength) of the radiation that can be absorbed or emittted depends on the molecules structure
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