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Energy
An agent capabe of setting an object in motion
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Joule
Standanrd unit of measurement of energy in scientific applications
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Power
rate at which energy is released, transferred, or received.
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Electromagnetic Radiation
The energy emitted by the sun and transferred to the Earth. Provides energy for movement of the atmosphere, growth of plants, evaporation of water etc.
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Kinetic Energy
(as opposed to Potential Energy) Energy in use/of motion
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Potential Energy
(as opposed to Kinetic Energy) Energy that hasn't yet been used
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Conduction
(one of 3 energy transfer mecahnisms) The movement of heat through a substance without the movement of molecules in the direction of heat transfer (ex. - a metal rod held partially over fire, part of rod over fire heats, which makes the part of rod not over fire heat as well by heating the molecules next to the ones over the fire)
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Convection
(one of 3 energy transfer mechanisms) The transfer of heat by the mixing of a fluid
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Buoyancy
The tendency for a light fluid (liquid or gas) to float upward when surrounded by a heavier fluid
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Radiation
(one of 3 energy transfer mechanisms) [The only one of the 3 that can occur without a transfer medium] The transfer of energy through empty space.
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Wavelength
the distance between any two corresponding points along the wave
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micrometers (microns)
unit measurement of wavelengths
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Blackbodies
perfect emitters of radiation that emit the maximum possible radiation at every wavelength, purely hypothetical, do not really exist
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Stefan-Boltzmann Law
states that a doubling of temperature produces MORE than a doubling of the amount of radiation emitted.
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graybodies
emit some percentage of the maximum radiation possible at a given temperature (most liquids and solids are graybodies, as blackbodies don't exist)
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emissivity
The percentage of energy radiated by a substance relative to that of a blackbody.
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Wien's Law
tells us that hotter objects radiate at shorter wavelengths than do cool objects.
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shortwave radiation
radiation with wavelengths less than 4 um (microns)
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longwave radiation
radiation with wavelengths longer than 4 um (microns)
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Core
Interior of the sun, where nuclear fusion is produces energy that is ultimately radiated to the Earth.
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inverse square law
states that as the distance of the sun increases, the intensity of the radiation deminishes in porportion of the distnace squared.
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solar constant
the "constant" (steady) solar output of an object
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insolation
the seasonal and latitudinal receipt of incoming solar radiation
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ecliptic plane
The imaginary plane on which Earth orbits the sun for 365 1/4 days (1 year)
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revolution
Earth's annual trip around the ecliptic plane (around the sun)
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perihelion
the point at which Earth is nearest to the sun (around Jan 4)
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aphelion
the point at which Earthh is farthest from the sun (Around July 4)
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rotation
the spinning motion Earth undergoes around its axis every 24 hours
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Polaris
Earth's axis is always pointed in the same direction and always at the same star. This star is called Polaris (The North Star)
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June Solstice
(summer solstice for northern hem, winter for southern hem) The point at which the Northern Hemisphere has its maximum tilt rowards the sun (around June 21), first day of summer
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December Solstice
(winter solstice for Northern Hem, summer sol for southern hem) The point at which Earth is at its minimum availibility of solar radiation
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March Equinox and September Equinox
Intermediate between the two soltices, every place on Earth has 12 hours of day and 12 hours of night
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Tropic of Cancer
23.5 degrees N., the most northward lattitude at which the subsolar point (the point at which the earth and the sun's rays meet at a right angle) is located during the summer solstice. The sun never appears directly overhead above this point.
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Tropic of Capricorn
23.5 degrees S., same as Tropic of Cancer only to the south and occurs during the winter solstice
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solar declination
the latitudinal position of the subsolar point
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Arctic Circle
line of lattitude of 66.5 degrees N.), northern limit of which experiences 24 hours of daylight or darkness
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Antartic Circle
line of lattitude of 66.5 degrees S.), southern limit of which experiences 24 hours of daylight or darkness
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Beam Spreading
the increase in the surface area over which radiation is distributed in response to a decrease in of solar angle. The greater the spreading, the less intense the radiation is.
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