Interaction Between Radiation and the Material. Prof. Arnon Karnieli The Remote Sensing Laboratory Jacob Blaustein Institute for Desert Research Ben-Gurion University of the Negev Sede-Boker Campus 84990, ISRAEL. Radiation Interaction with a Matter. Transmission.
Prof. Arnon Karnieli
The Remote Sensing Laboratory
Jacob Blaustein Institute for Desert Research
Ben-Gurion University of the Negev
Sede-Boker Campus 84990, ISRAEL
Transmitted waves are refracted or diffracted:
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.
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.
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:
- The material is opaque to incident radiation
- A portion of EMR is converted to heat (re-radiated)
- Diffuse reflection (rough surface)
- Specular reflectance (smooth surface)
Nitrogen (N2) - 78%, Oxygen (O2) - 21%, Carbon Dioxide (CO2) - 0.03 %, plus other miscellaneous gases (e.g., H2O).
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.
2. The longer the wavelength, the lesser statistical probability for a contact between the radiation and the atmospheric particles.
Scattering: random re-direction of the radiation ray from parallel orbit to to an omni-direction orbit.
1. Selective scattering
- Rayleigh scattering
- Mie scattering
2. Non-selective scattering
Partical size <<
Type of particles: gases, atmospheric molecules
Mostly affects blue light
Mean diameter 0.1 to 10m
Type of particles: dust, smoke, soot, volcanic ash, water vapor, polen
Mostly affects red light
Haifa, Israel, November 2004
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.
Stead, Nevada, April 28, 1998
Partical size >>
Type of particles: water droplets, crystal ice.
Affects all wavelength equally
Independent of wavelength 0