Geology 1350 Lecture 22 Outline of Last Lecture I. Air PollutionOutline of Current Lecture I. Light color and atmospheric opticsCurrent LectureReflection, scattering, refraction, diffraction- gases aerosol and hydrometer particlesVarious optical phenomena- blues skies, rainbowseyes are sensitive to light and color and we see objects because of the light and color that they reflect scattering- depends on the size of the objects in particular on the ration diameter of objects vs wavelengthtypes- Rayleigh: (air molecules)blue sky red sunsets, mie(aerosols) brownish smog, geometric:(cloud droplets)white cloudsgas scattering- redirection of radiation by a gas molecule without a net transfer of energy of the molecules (Rayleigh), the longer pathway of light through the atmosphere the more short wavelength are scattered, shortly before sundown in unpolluted air: blue light and a lot of green light scatters, yellow sun; special effects in forests: blue ridge mtn. /Virginia blue mtns. /Australia, scattering of blue light by aerosols, dust and salts are large enough to cause geometric scattering and change blue skies into hazy white skiesaersols and hydrometeor particle scattering- redirection of radiation by a particle without a loss of energy to the particle: reflection-the angle of incidence equals the angle of reflection, refraction- change of medium if different density, speed of wave changes, if wave travels into a medium of higher density it refracts toward the surface normal, depends on wavelength refraction bends short wavelengths more than long wavelengths, example is dispersion of white light into individual colors through a glass or ice crystal prism, special case refraction These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.and twilight refraction or needing of sunlight creates an apparent sunrise and late sunset, alsocauses the sun to flatten at its base , diffraction- wavefront encounters an object causing series of secondary concentric waves, waves overlap, bending of light; most important is diffraction and double refraction- particles scatter light primarily in the forward direction, single internal reflection, backscattering., rainbow- dispersive refraction, reflection, viewers eye only sees one wavelength from each raindrop, rain is in front and sun is in the back, after the rain is gone, colors split and enter therain drop at a specific angle, the backside, and creates reflection, after the reflection the blue and red will exit the droplet takes out the radiation and occurs another reflection red color hits your eye and blue passes by , in order to see the blue you need additional raindrops, different droplets appear when you move and that depends whether you see the red or blue colorabsorption extinction coefficients- cloud water droplets are poor absorption og light but large enough to reflect all wavelengths as geometric scatters, ……fractions or reflected transmitted and absorbed radiation depending on cloud thicknesssummary of blue and white clouds- selective scattering of blue light by air molecules producesthe blue sky, scattering of all wavelength of visible light in liquid lcloud droplets produces white cloudsadditional examples, colors in the atmos- white hazes and clouds, high relative humid, aerosolparticles increases in size by absorbing liquid water, mie scattering of all wavelengths with equal intensity whitish colorreddish and brown color in smog- no2: absorption of blue and some green light often during morning hours when no2 mixing ratios are high, nitrated aromatics and PAHS : absorptions of blue light, soil dust aerosols: absorptions of blue and green lightblacks colors in smog- black carbon what happens to no2 in sunny days- photolesis, light will split the no2 moleculered skies and brilliant horizon in smog- aerosol particles: scattering of blue green and red light ,gas molecules :scattering of blue and green lightglory- the glory around the aircraft shadow is attributed to diffraction but based partly on surface refraction to create the bending that brings the light back to the viewerwe have more optical phenomenon if there is more ice , cirrus clouds- ice crystals halo- cirriform cloud ice crystals randomly oriented to the ground refract light at an angle of 22 tocreate an arc, less common are the 48 degree halo which require more regular column type crystalssun dogs and dispersion- ice crystals selectively refract and bend sun to create brightly colored red spots on either side of the sun example, glacier bay, Alaskareflection and sun pilar- reflection of lightdiffraction and coronas- solar and lunar coronas are caused by diffraction or bending of light as it passes around through ice crystalsinferior mirage- refraction of light by density differences is the cause for a mirage creating an apparent figure, when very hot air rests below air , light transmitted bends upwards creating a line of sights into the groundsuperior mirage- occurs when warm air rests above cold air, causing the line of sight to head upward and the object appear at a higher attitude, example you see high mountains when they are really smaller because of exceptional temperature, its all about