Physical Science Review for Exam IV -May 16, 2002
Light and Color
Mixing additive primary-colored lights: red, green, blue.
Describe the experiment and the results.
Computer simulation of same experiment.
How color computer screens work - red, green, blue dots
Subtractive primaries and pigments - magenta, yellow, and cyan
Why are they called subtractive primaries?
Overhead spectrograph
Spectra of red, green, and blue filters
Spectra of magenta, yellow, and cyan
Overlap of primary filters - no light gets through because spectra
don't overlap
Overlap of subtractive filters - common color gets through
Spectra of hydrogen discharge
Spectra of helium and neon
Spectra of sun - continuous, like projector, but absorption lines superimposed
from elements in sun's atmosphere
Rainbow
Prism and dispersion
What is dispersion? different colors (wavelengths) have different refractive
indices
Raindrop - path of light in raindrop to make the rainbow
Where must one look to see rainbow?
Explain 3 techniques for measuring rainbow angle - angle sticks, photography,
projector and artificial raindrop
Relative Humidity and barometric pressure
Definition of Rel. Humidity
Definition of absolute humidity
How to measure RH?
Why does the wet bulb become cool in the psychrometer?
Why does high RH and high temperature make one uncomfortable?
What is barometric pressure?
How do we determine difference in elevation using barometer?
How does a barometer work?
How does a recording barometer (barograph) work?
What causes the relative variation in barometric pressure through weather
cycles? Descending air makes larger pressure; ascending air causes
lower pressure.
Global air circulation
Convection
Hadley cells - draw the cross-section
Coriolis effect - what is it? How did we demonstrate it in the
lab?
Prevailing winds - trade winds, westerlies, polar easterlies - combined
from Hadley cells and coriolis effect
Cyclone - ccw circulation around a low pressure in N. Hemisphere. Opposite
direction in S. hemisphere. Coriolis effect causes the circulation
Difference between cyclone and tornado - many people call tornados
cyclones.
Anti-cyclone - cw circulation around high pressure in N. Hemisphere.
Opposite in S. hemisphere.
Weather patterns - stationary front is boundary between polar and temperate
cyclone.
Cyclones develop along this front and front breaks between cold and
warm fronts
"Stationary" front meanders N and S and globe is "checkerboarded" with
alternate cyclones and anti-cyclones
Deep sky objects - Galaxies and globular clusters - see web site
Number of stars in each
Examples of distances
Shape of each