1 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 Prof. Arnon Karnieli The Remote Sensing Laboratory Jacob Blaustein Institute for Desert Research Ben-Gurion University of the Negev Sede-Boker Campus 84990, ISRAEL

2 Radiation Interaction with a Matter

3 Transmission - Incident radiation passes through the material without attenuation - Change in the direction of radiation is given by the index of refraction of the material

4 Refraction 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:

5 Index of Refraction 22 11 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:

6 - The material is opaque to incident radiation - A portion of EMR is converted to heat (re-radiated) Absorption

7 Reflectance - Diffuse reflection (rough surface) - Specular reflectance (smooth surface) Reflection

8 (DIFFUSE) Scattering

9 Radiation Budget Equation

10 Radiation Interaction with the Atmosphere

11 Atmosphere Effect on Satellite Image With atmosphereNo atmosphere

12 Nitrogen (N 2 ) - 78%, Oxygen (O 2 ) - 21%, Carbon Dioxide (CO 2 ) %, plus other miscellaneous gases (e.g., H 2 O). Atmospheric Gases

13 Aerosol Types and Origin

14 Atmospheric Absorption

15 Atmospheric Absorption

16 Atmospheric Windows and Shutters

17

18 Scattering Vs. Absorption

19 E p = h*c/ Rules - 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.

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

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

22 Scattering

23 Scattering Types 1. Selective scattering - Rayleigh scattering - Mie scattering 2. Non-selective scattering Scattering Types

24 Type of particles: gases, atmospheric molecules Mostly affects blue light Partical size << Scattering intensity Selective: Rayleigh Scattering

25 A Clear Blue Sky

26 Red Sunsets

27 Red Sunsets

28 Far Landscape

29 Skylight

30 UV/Skylight Filter

31 No FilterSkylight Filter UV/Skylight Filter

32 Shadows on the Moon

33 Black Sky

34 Black Sky

35 Type of particles: dust, smoke, soot, volcanic ash, water vapor, polen Mostly affects red light Partical size  Scattering intensity to Mean diameter 0.1 to 10  m Selective: Mie Scattering

36 Haifa, Israel, November 2004 Mie Scattering – Air Pollution

37 Mie Scattering – Biomass Burning

38 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 Eruption

39 Mie Scattering – Dust Storm

40 Mie Scattering – Haze Episode Stead, Nevada, April 28, 1998

41 Partical size >> Type of particles: water droplets, crystal ice. Affects all wavelength equally Independent of wavelength 0 Nonselective Scattering

42 Nonselective Scattering

43 Scattering - Summary