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Published byNoel Poole Modified over 9 years ago
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Solar Radiation: The driving factor Radiation (energy transmitted as waves, rays and particles) released, absorbed & reflected by all things travels as both a particle and a wave is affected by - - gravity, magnetism, and atmosphere composition, distance, angle of incidence provides Earth with an external source of energy
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The sun produces most of its electromagnetic energy in intermediate wavelengths / frequencies. A.True B.False
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Sources of radiation Sun and other stars are dominant source -Sun is closest so it has a greater influence Earth emits some energy as well -Solar radiation is absorbed by Earth and transformed into longwave radiation Many other planets emit radiation as well -e.g., Jupiter and Saturn -source is from the planet itself not all is absorbed and re-emitted like Earth
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The Sun 93 million miles from Earth It rotates once every 600 hrs (25 days) Has hot spots and "cool" spots -sunspots are relatively "cool" Produces electro- magnetic radiative energy -concentrated in UV, Visible & IR spectral classes
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Sunspots - cyclical magnetic “storms” that occur in 11 year cycles are lower in temperature, but increase solar output. Solar Max = lots of sunspots and increased energy output Solar Min = few to no sunspots and decreased energy output
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Frequency (mHz) refers to vibration of particles Wavelength ( ) = distance between wave crests Electromagnetic Spectrum Long Short ((
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Position affects radiation Far away=less radiation Titled toward= more radiation Far away=less radiation; Closer=more radiation Titled away=less radiation; Tilted toward = more
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The northern hemisphere experiences winter because the Earth is farther away from the Sun than it is during the summer months. A.True B.False
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Eccentricity 100 kyr cycle aphelion Earth’s orbit
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Obliquity 41 kyr cycle Perpendicular to the ecliptic Axis 20 kyr ago Axis at present Axis at 20 kyr in future
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Conditions now Conditions 11 kyr ago Precession of Equinox 22 kyr cycle sun Earth at aphelion Earth at perihelion Path of Earth’s orbit around the sun
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Precession 22 kyr cycle
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Milankovitch cycles- pacemaker to the ice ages from O 18 ice and deep sea sediment cores *
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The atmosphere acts as a mirror, prism and a trap Scatters some of the radiation -why the sky is blue Reflects some of the radiation -clouds, snow, water etc. Absorbs some of the radiation -ground, ozone, dust, etc. Ozone & dust Dust & clouds Clouds & gases mirror prism trap
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Albedo ・ A measure of the amount of reflected radiation ・ Some things reflect radiation better than others -"dry" or "cold" Snow & Ice = high albedo -water = moderate for visible, low for infrared -plants= moderate for visible ・ Land absorbs and releases radiative energy quicker than water Albedo = ________________ incident radiation reflected radiation
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Albedo of land surfaces on Earth Data collected by NASA’s MODIS satellite, April 2002 Warm colors are higher; cool are lower; white no data available
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IR output from Earth K
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Effects of cloud type on radiation budget different types of interference have different effects on Earth's energy budget
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