Principles Problem Set
Corrections indicated below for Problem 6.
Updated to include constants necessary to compute
some of the problems.
Solve the problems below using the equations and
concepts discussed in class. Include units with all the answers and
discussion were appropriate.
1. The meter (m) is the basic unit in which
wavelengths are measured. Convert 0.5 micrometers to its equivalent
frequency. Also convert 33GHz (common unit of measure in the microwave
portion of EMR) to wavelength (in meters and micrometers).
2. Calculate the total radiant exitance from
the sun assuming it is a 6000K blackbody. Also, determine the wavelength
of maximum emission (in micrometers). This corresponds with what wavelength
3. Compute the total radiant exitance from a blackbody with a temperature
of 300K. Determine the wavelength of maximum emission (in micrometers).
This corresponds with which wavelength region? Discuss importance
in relation to the Earth as a blackbody.
4. The radiant flux from the sun is 3.9x1026 W. Calculate the
solar constant (Wm-2). The solar constant is the flux per square
meter of solar radiation at the outer boundary of the Earth's atmosphere
that is received on the surface held perpendicular to sun's rays, averaged
over the year.
5. Suppose that the sun were somewhat bluer in color, so that its wavelength
of maximum irradiance were 0.400 micrometers instead of 0.475 micrometers.
Estimate the radiative equilibrium temperature of the earth under these
conditions, assuming the albedo remains the same.
6. A body is emitting radiation in the
following idealized spectrum of monochromatic radiation:
lambda < 0.35 um, Elambda = 0
0.35 um < lambda < 0.50 um, Elambda = 1.0 Wm-2
0.50 um < lambda < 0.70um, Elambda = 0.5 Wm-2
0.70 um < lambda < 1.00 um, Elambda = 0.2
lambda > 1.00 um, Elambda
Compute the irradiance.
7. 150 Wm-2 of direct 'red' solar radiant flux irradiates
a soil surface with a 'red' absorptance of 0.80. How much energy is reflected
from the surface?
8. On a hazy day, what type of scattering dominates. Explain.
9. Explain why the sky appears brilliant colors of orange and red during
10. You are a geologist looking at finding particular
mineral resources associated with oil and gas reserves using satellite
data. The mineral resources are spectrally sensitive in the ultraviolet
through mid-infrared region of the spectrum. What portions of this region
would be most beneficial for your investigation?
speed of light (c) = 2.99792458 x 108m
Stefan-Boltzman's constant (sigma) = 5.67051 x 10-8 m-2
mean Sun-Earth distance (dse) =1.4956 x 1011 m
radius of Sun (rs) = 6.9595 x 108
radius of Earth (re) = 6.371009
x 106 m
Due on Friday, October 1, 1999.
to Geog474 Homepage
Last revised on September 23, 1999 by Tracy DeLiberty.