METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.
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Transcript of METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.
![Page 1: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/1.jpg)
METR125: Light, Color, and Atmospheric Optics
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter19/
color.html
![Page 2: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/2.jpg)
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
![Page 3: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/3.jpg)
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
![Page 4: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/4.jpg)
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
![Page 5: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/5.jpg)
A black object
• an object will appear black when it absorbs all wavelengths of visible light.
• therefore, no light is scattered to our eye.
![Page 6: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/6.jpg)
Processes affecting propagation of electromagnetic radiation
what can happen to visible light as it passes through the atmosphere?
Class Discussion
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Processes affecting propagation of electromagnetic radiation
what can happen to visible light as it passes through the atmosphere?
• Reflection
• Scattering
• Transmission
• Refraction
• Diffraction
![Page 8: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/8.jpg)
Reflection of Light
• light can simply be reflected
• the incident angle (a) will equal the reflected angle (b)
![Page 9: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/9.jpg)
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?????
![Page 10: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/10.jpg)
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?
![Page 11: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/11.jpg)
![Page 12: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/12.jpg)
![Page 13: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/13.jpg)
![Page 14: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/14.jpg)
Rayleigh and Mie Scattering
what processes explain:• blue sky • haze • white cloud • dark areas in cloud
Class Participation Activity
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Crepuscular Rays
• bright light beams due to Mie scattering by haze and dust
• seen most often near sunrise and sunset
![Page 16: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/16.jpg)
what causes red sunsets and clouds to appear orange/red near sunset?
![Page 17: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/17.jpg)
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.
![Page 18: METR125: Light, Color, and Atmospheric Optics et130/notes/chapter19/color.html.](https://reader036.fdocuments.us/reader036/viewer/2022062322/56649e795503460f94b7969d/html5/thumbnails/18.jpg)
Why do clouds also appear red in sunset?
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Transmission of light
• occurs when light passes through an object
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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.
• 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