1. Mechanisms Particle/Molecule-light interactions responsible
for creating optical effects. These interactions include:
reflection, scattering, refraction and diffraction. 2. Air, Dust,
Haze Optical effects resulting from the interaction of light with
air, dust and haze particles. These effects include: crepuscular
rays, blue skies, blue haze and sunsets.
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3. Ice Crystals Optical effects resulting from the interaction
of light with ice crystals. These effects include: sundogs, sun
pillars and halos. 4. Water Droplets Optical effects resulting from
the interaction of light with water droplets. These effects
include: cloud iridescence, rainbows and a silver lining along the
edge of clouds Mirages: Fata Morgana
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1. Ray Optics The Law of Reflection Examples: sun glint -
reflection of the solar disk off water. sparkling of snow surface -
snow crystals acting like little mirrors. Example photo. sun
pillars - caused by reflection of sunlight off crystals.
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Refraction The law of refraction is n1sinq1= n2sinq2 Examples
of refraction Refraction causes a setting sun to look flat
Twinkling, or scintillation, if stars Twilight caused by refraction
and scattering. Atmospheric mirages are caused by light passing
through and being refracted by air layers of different densities.
Densities differences can be caused by temperature changes. Fata
Morgana Halos - appear with ice clouds. Crystals have to be small
15 or 20 microns. Shadows on the bottom of a pool.
2. WHY IS THE SKY BLUE? The blue color of the sky is due to
Rayleigh scattering. As light moves through the atmosphere, most of
the longer wavelengths pass straight through. Little of the red,
orange and yellow light is affected by the air.
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PROJECTS TO DO TOGETHER PROJECT 1 - Split light into a spectrum
What you need: a small mirror, a piece of white paper or cardboard,
water a large shallow bowl, pan, or plastic shoebox a window with
direct sunlight coming in, or a sunny day outdoor What to do: Fill
the bowl or pan about 2/3 full of water. Place it on a table or the
floor, directly in the sunlight. (Note: the direct sunlight is
important for this experiment to work right.) Hold the mirror under
water, facing towards the sun. Hold the paper above and in front of
the mirror. Adjust the positions of the paper and mirror until the
reflected light shines on the paper. Observe the colored spectrum.
What happened ?
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3. Ice Crystals Sundogs (mock suns or parhelia) Sundogs, also
known as mock suns or "parhelia", are a pair of brightly colored
spots, one on either side of the sun.
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Sun Pillars vertical shafts of light A sun pillar is a vertical
shaft of light extending upward or downward from the sun
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Halo
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Coronas produced by diffraction of light. This 'crown' of light
around the sun or moon is called the corona.
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4. Water Droplets Iridescent Clouds
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What is a rainbow? Where is the sun when you see a rainbow?
What makes the bow?
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What makes the colors in the rainbow? What does a rainbow look
like through dark glasses?
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What are Reflection Rainbows? What makes a double rainbow?
Simulating a Rainbow
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Silver Lining and Cloud Iridescence produced through
diffraction of sunlight
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Mirage Roadmirage
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Trees shown which are normally invisible below horizon, a
superior mirage refracted from above Sunrise first light caused by
super-refracted sunlight Double sun sunrise caused by a
super-refracted sun