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Interaction Between

Radiation and the Material

Interaction Between

Radiation and the Material

Prof. Arnon Karnieli 

The Remote Sensing LaboratoryJacob Blaustein Institute for Desert Research

Ben-Gurion University of the NegevSede-Boker Campus 84990, ISRAEL

Prof. Arnon Karnieli 

The Remote Sensing LaboratoryJacob Blaustein Institute for Desert Research

Ben-Gurion University of the NegevSede-Boker Campus 84990, ISRAEL

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Radiation Interaction with a MatterRadiation Interaction with a Matter

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TransmissionTransmission

- Incident radiation passes through the material without attenuation

- Change in the direction of radiation is given by the index of refraction of the material

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Refraction and DiffractionRefraction and Diffraction

Diffraction refers to the "bending of waves around an edge" of an object. Diffraction depends on the size of the object relative to the wavelength of the wave.

Refraction occurs when an electromagnetic wave crosses a boundary from one medium to another. A wave entering a medium at an angle will change direction.

Transmitted waves are refracted or diffracted:

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Index of Refraction Index of Refraction

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Index of refraction (n) is the ratio of the speed of light in vacuum relative to the speed of light through the material

Snell’s law describes refraction angles:

1 1 2 2sin sinn n

/ nn c c

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- The material is opaque to incident radiation

- A portion of EMR is converted to heat (re-radiated)

AbsorptionAbsorption

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Reflectance

- Diffuse reflection (rough surface)

- Specular reflectance (smooth surface)

ReflectionReflection

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(DIFFUSE)

ScatteringScattering

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)()()()( TARI EEEE

Radiation Budget EquationRadiation Budget Equation

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Radiation Interaction with the AtmosphereRadiation Interaction with the Atmosphere

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Atmosphere Effect on Satellite ImageAtmosphere Effect on Satellite Image

With atmosphere No atmosphere

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Nitrogen (N2) - 78%, Oxygen (O2) - 21%, Carbon Dioxide

(CO2) - 0.03 %, plus other miscellaneous gases (e.g., H2O).

Atmospheric GasesAtmospheric Gases

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Aerosol Types and OriginAerosol Types and Origin

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Atmospheric AbsorptionAtmospheric Absorption

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Atmospheric AbsorptionAtmospheric Absorption

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Atmospheric Windows and ShuttersAtmospheric Windows and Shutters

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Scattering Vs. AbsorptionScattering Vs. Absorption

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Ep= h*c/

Rules - 1Rules - 1

Rules govern the interaction between energy and the atmospheric media:

1. Since there is an indirect relationship between the energy of the photon and the wavelength, less electronic influence on the atmospheric particles is expecting in

long wavelengths.

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2. The longer the wavelength, the lesser statistical probability for a contact between the radiation and the atmospheric particles.

Rules - 2Rules - 2

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Scattering: random re-direction of the radiation ray from parallel orbit to to an omni-direction orbit.

ScatteringScattering

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ScatteringScattering

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Scattering Types

1 .Selective scattering- Rayleigh scattering - Mie scattering

2. Non-selective scattering

Scattering TypesScattering Types

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Type of particles: gases, atmospheric molecules

Mostly affects blue light

Partical size <<

Scattering intensity 41/I

Selective: Rayleigh ScatteringSelective: Rayleigh Scattering

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A Clear Blue SkyA Clear Blue Sky

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Red SunsetsRed Sunsets

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Red SunsetsRed Sunsets

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Far LandscapeFar Landscape

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SkylightSkylight

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UV/Skylight FilterUV/Skylight Filter

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No Filter Skylight Filter

UV/Skylight FilterUV/Skylight Filter

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Shadows on the MoonShadows on the Moon

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Black SkyBlack Sky

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Black SkyBlack Sky

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Type of particles: dust, smoke, soot, volcanic ash, water vapor, polen

Mostly affects red light

Partical size

Scattering intensity 41/I to 0

Mean diameter 0.1 to 10m

Selective: Mie ScatteringSelective: Mie Scattering

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Haifa, Israel, November 2004

Mie Scattering – Air PollutionMie Scattering – Air Pollution

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Mie Scattering – Biomass BurningMie Scattering – Biomass Burning

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Mt. Pinatubo stratospheric Aerosol layer as seen from Space Shuttle STS-43 (August 1991). The stratospheric aerosol layer forming two distinct strata is clearly visible approximately 10 kilometers above the cloud tops.

Mie Scattering – Volcanic EruptionMie Scattering – Volcanic Eruption

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Mie Scattering – Dust StormMie Scattering – Dust Storm

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Mie Scattering – Haze EpisodeMie Scattering – Haze EpisodeStead, Nevada, April 28, 1998

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Partical size >>

Type of particles: water droplets, crystal ice.

Affects all wavelength equally

Independent of wavelength 0

Nonselective ScatteringNonselective Scattering

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Nonselective ScatteringNonselective Scattering

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Scattering - SummaryScattering - Summary