170 likes | 245 Views
PHYSICS OF RADIATION IN REMOTE SENSING. Task proposal for the classroom. OBJECTIVES. There is no Remote sensing without physics. Pupils should learn which main physical laws are necessary for remote sensing difficult physical laws could be demonstrated by excel. REMOTE SENSING.
E N D
PHYSICS OF RADIATION IN REMOTE SENSING Task proposal for the classroom
OBJECTIVES There is no Remote sensing without physics. Pupils should learn • which main physical laws are necessary for remotesensing • difficult physical laws could be demonstrated by excel
REMOTE SENSING • Radiation transports information from an object to a receiver • Information: - reflected sunlight from vegetation
REMOTE SENSING - microwave radiation scattered from a rain cloud or a forest This RADARSAT image of Slamet Volcano (3428m) in central Java demonstrates the usefulness for imaging areas in tropical zones, where a cloud free optical satellite image might take months or years to acquire. Slamet Volcano, Java, Indonesia
ELECTROMAGNETIC SPECTRUM The valleys, like at the left end of the scale for visible light, are the "windows" where there is very little attenuating of the radiation by the medium it passes through.
Stefan Boltzmann law Black bodies: - they are perfect absorber in visibel region they are also perfect emitters they emit radiation at all wavelengths but the intensity emitted at different wavelength is not equal The total intensity is given by the STEFAN-BOLTZMANN law: : Stefan-Boltzmann constant=5,6703 10-8 W m2 K4 W = T4 T : absolute temperature W: total intensity emitted by the black body – integrated over all wavelength
Planck‘s law h: Planck constanth=6,6260755 e-34 J sk: Boltzmann constantk=1,380658 e-23 J/K The distribution of radiation with wavelengths is given by PLANCK‘s law: T : absolute temperature W: spectral energy density c: light speed Demonstration in EXCEL
Wien‘s deplacement law b : Wien‘s constantb=2.897756 * 10-3 mK T : absolute temperature The electromagnetic spectrum passes through a maximum at a wavelength which depends on temperature: Demonstration in EXCEL m
ACTIVITY • When you change the temperature of an object what two things do you change about the light it emits? • Why is RADARSAT to be used for imaging areas in tropical zones? • What is the shortest and the longest wavelength of visible light? • Specify the main properties of black bodies. • Calculate the max at the temperatures of 300 K and 6000 K. (Use the Excelsheet!)
References Websites • http://www.sea.uct.ac.za/Department/SEA202S/phys.htm • http://www.sea.uct.ac.za/Department/SEA202S/phys2.htm • http://satgeo.zum.de/satgeo/methoden/physik_fernerkundung/spektrum/reflexion_absorption.htm • http://www.npagroup.co.uk/imagery/rs_intro/sar.htm • http://www.everythingweather.com/atmospheric-radiation/absorption.shtml