Presentation on theme: "METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html."— Presentation transcript:
METR125: Light, Color, and Atmospheric Optics http://apollo.lsc.vsc.edu/classes/m et130/notes/chapter19/color.html
Why do objects have color? objects appear to have color since they are able to selectively absorb and reflect certain wavelengths of visible light..... The sun emits white light - the sum of all wavelengths (colors) of visible light together
White Object An object will appear white when it does not absorb any wavelength of visible light.... it is all scattered hence, the object will appear white
A Red Object An object will appear red when it absorbs all wavelengths of visible light except for red.... red light is scattered to our eye, so the object looks red
A black object an object will appear black when it absorbs all wavelengths of visible light. therefore, no light is scattered to our eye.
Processes affecting propagation of electromagnetic radiation what can happen to visible light as it passes through the atmosphere? Class Discussion
Processes affecting propagation of electromagnetic radiation what can happen to visible light as it passes through the atmosphere? Reflection Scattering Transmission Refraction Diffraction
Reflection of Light light can simply be reflected the incident angle (a) will equal the reflected angle (b)
Mie Scattering Light can be scattered.....redirected in many directions We will consider two types of scattering that occur in the atmosphere Mie Scattering large particles in the atmosphere are able to scatter all wavelengths of white light equally when all wavelengths of white light are scattered equally, then Mie scattering is occurring this is why clouds appear white.... however, if a cloud is optically thick, then little light will penetrate through the cloud.... when little light can penetrate to a particular location in a cloud, such as cloud base, how will it look?????
Rayleigh Scattering ( Scattering, continued) Why is the sky blue? It's because of Rayleigh scattering - the selective scattering of the shorter wavelengths of visible light (violet and blue) by atmospheric gases. Note that Rayleigh scattering involves much smaller scattering particles than Mie scattering Class Think; if there were no atmosphere, what color would the sun look like?
Rayleigh and Mie Scattering what processes explain: blue sky haze white cloud dark areas in cloud Class Participation Activity
Crepuscular Rays bright light beams due to Mie scattering by haze and dust seen most often near sunrise and sunset
what causes red sunsets and clouds to appear orange/red near sunset?
orange/red sunsets in a dirty atmosphere when pollution is present, the atmosphere contains more particles such as aerosols having larger diameters than the atmospheric gases hence, more of the intermediate wavelengths of visible light such as yellow and green are scattered in addition to the blue light what largely remains is red light...., hence the sun appears red.
Transmission of light occurs when light passes through an object
Refraction of Light is the bending of light as it passes from one medium to another with different densities. amount of refraction depends upon: –density of the materials –angle at which the light enters the material –wavelength - causes colors of white light to separate when passing through a prism.causes colors of white light to separate when passing through a prism. light will bend away from the normal when passing into a less dense medium light will bend toward the normal when passing into a more dense medium