The mirage

advertisement
Chapter 15: Light,
color and
atmospheric optics









White and colors
White clouds and scattered light
Blue skies and hazy days
Red suns and blue moons
Twinkling, twilight, and the green flash
The mirage: seeing is not believing
Halos, sundogs, and sun pillars
Rainbows
Coronas and cloud iridescence
White and colors
White and colors


review of fate of visible light passing
through the atmosphere
review of relationship between wavelength
and colors
White clouds and
scattered light
White clouds and scattered
light


reflection
scattering
• Thunderstorms appear dark because the clouds
(cumulonimbus) are about 10 km deep, scattering
most of the light.
Blue skies and hazy
days
Blue skies and hazy days



selective scattering
effect of scattering particle size
crepuscular rays
Red suns and blue
moons
Red suns and blue moons


path length of sunlight passing through the
atmosphere
atmospheric particle effects
• The “definition” of a blue moon as two full moons in
a single calendar month has nothing to do with
atmospheric optics.
The mirage: seeing is
not believing
The mirage: seeing is not
believing


inferior mirage
superior mirage
• Mirages are very common and may be seen frequently
if you look for them.
Inferior mirage

warm surface, decreasing temperatures
aloft
• The proper conditions for an inferior mirage are commonly
found over a hot road surface during summer, or over
an unfrozen lake on a very cold day.
Superior mirage

cold surface, warmer temperature aloft
• The proper conditions for a superior mirage are commonly
found over water and over snow-covered surfaces.
Fata morgana

complex vertical temperature profile
• According to legend, King Arthur’s half-sister,
Fata Morgana in Italian, was a fairy enchantress
trained by Merlin the Magician. She lived in a crystal
palace beneath the water and could build fantastic
castles from thin air.
Halos, sundogs, and
sun pillars
Halos


ice crystals
dispersion
• Halo-producing ice crystals are commonly found
in cirrostratus clouds
Sundogs


hexagonal ice crystals
horizontal orientation
• Sundogs are commonly seen when cirrostratus clouds
are in the sky.
Sun pillars

reflection phenomenon
• Sun pillars can be seen shortly after sunrise or
shortly before sunset on very cold days.
Rainbows
Rainbows




water droplet phenomenon
reflection and dispersion
necessary conditions for a rainbow
the primary rainbow
The secondary rainbow

two internal reflections
• A tertiary rainbow also exists, but it is too faint to
be seen with the human eye.
Coronas and cloud
iridescence
Coronas and cloud
iridescence

diffraction
The corona

necessary conditions
Cloud iridescence

another water droplet diffraction
phenomenon
The Glory

necessary conditions for viewing
• It is very common to see a glory from the window
of an airplane. Make sure you are sitting on the
side opposite the sun.
Download
Related flashcards

Photography

13 cards

Spectroscopy

36 cards

Create Flashcards