AT622, Review Material for Test 1
Maxwell’s Equations: We learned a rough history of light. Understand basic princples of
what an electromagnetic wave is (how E & B are related, where the speed of light comes
from in the equations, how E-field is modified in an absorbing medium with a non-zero
imaginary part of the refractive index).
Electromagnetic spectrum: basic parts of the spectrum, long vs. short wave, what is
important about each part of the spectrum for atmospheric science (basically ch3 Petty).
Solid Angle: Know the equation for calculating solid angle. Solid angle of a sphere viewed
from anywhere.
Quantities: Intensity/Radiance, Flux Density (spectral vs. monochromatic) = Irradiance,
power, energy. Know the units on every such quantity we’ve talked about.
Equation for flux density from radiance (angular integration). Remember the cosine term
and why it is there.
Planck’s function: What it describes. Limits: Wien limit (short wavelength), Rayleigh-jeans
limit (long wavelength), and how to derive them. How is peak wavelength of emission
related to temperature? What is the Stefan-Boltzmann law, where does it come from?
What is the ultraviolet catastrophe, and what was the key in determining a physical basis
for deriving this formula?
What is brightness temperature; TB equation in the Rayleigh-Jeans limit and how to derive.
What is Kirchoff’s law? Terms: emissivity, absorptivity, reflectivity. Brightness
Interaction at a planar boundary: Snell’s law, critical angle. Depends on incidence angle &
index of refraction. What do the real vs. imaginary parts of index of refraction of a material
affect? Fresnel relations for reflectivity & transmissivity at a planar boundary & their
dependence on polarization state. Brewster’s angle.
Definition of surface albedo. Specular vs. Lambertian surfaces.
Solar stuff: Sun emits roughly as a blackbody at T=5870 K. Solar lines. Solar insolation:
equation for SZA, how to get daily averaged, how to calculate length of day. Limiting cases:
equinoxes, solstices, poles. Meanings of terms that determine solar insolation.
Radiation balance stuff, Fin=Fout. Calculating emitting temps of objects & surfaces, net
fluxes, heating rates.