Problems
165
distance. These variations are much smaller than other sources of uncertainty in the radiation budget, so we do not try to account for them in our
calculations, and assume that the solar input just outside the atmosphere
is constant and equal to the solar constant.
References
Brutsaert, W. (1 975) On a derivable formula for long-wave radiation from
clear skies. Water Resour. Res. 11: 742-744.
Brutsaert, W. (1984) Evaporation into the Atmosphere: Theory,
History, and Applications. Boston: D. Reidel.
Gates, D. M. (1980) Biophysical Ecology. New York: Springer Verlag.
Monteith, J. L. andM. H. Unsworth (1990) Principles ofenvironmental
Physics (2nd ed.). London: Edward Arnold.
Nicodemus, F. E., J. C. Richmond, J. J. Hsia, I. W. Ginsberg, and T.
Limperis (1977) "Geometrical considerations and nomenclature for reflectance." NBS Monograph 160, U.S. Dept. Commerce/National Bureau
Standards, 1977.
Problems
10.1. The median wavelength for solar radiation in the 0.3 to 3 pm wave
band is approximately 0.7 pm. If the irradiance is 1 kw/m2, what
is the photon flux?
10.2. When the energy flux density in the 400 to 700 nm waveband is
200 w/m2, what is the photon flux density of PAR (mol m-2 s-I)?
10.3. When photon flux density is 1000 pmol mW2 s-I in the 400 to
700 nm waveband, what is the energy flux density (w/m2) in the
PAR waveband? What is the flux density of solar radiation (all
wavelengths)?
10.4. What is the wavelength ofpeak emittance for a 2800 K incandescent
light bulb?
10.5. If your mean surface temperature is 28" C, what is your emittance?
If the mean wall temperature in the room in which you are standing
is 20" C, what is the average thermal irradiance at your surface?
Estimate your net radiant heat loss. Assume
= 0.97 and &, l l =
1.0.
10.6. Compare the radiant emittance of a clear sky and a completely
overcast sky, both at 0' C. How much additional radiant energy
does the ground receive on an overcast night?
165
distance. These variations are much smaller than other sources of uncertainty in the radiation budget, so we do not try to account for them in our
calculations, and assume that the solar input just outside the atmosphere
is constant and equal to the solar constant.
References
Brutsaert, W. (1 975) On a derivable formula for long-wave radiation from
clear skies. Water Resour. Res. 11: 742-744.
Brutsaert, W. (1984) Evaporation into the Atmosphere: Theory,
History, and Applications. Boston: D. Reidel.
Gates, D. M. (1980) Biophysical Ecology. New York: Springer Verlag.
Monteith, J. L. andM. H. Unsworth (1990) Principles ofenvironmental
Physics (2nd ed.). London: Edward Arnold.
Nicodemus, F. E., J. C. Richmond, J. J. Hsia, I. W. Ginsberg, and T.
Limperis (1977) "Geometrical considerations and nomenclature for reflectance." NBS Monograph 160, U.S. Dept. Commerce/National Bureau
Standards, 1977.
Problems
10.1. The median wavelength for solar radiation in the 0.3 to 3 pm wave
band is approximately 0.7 pm. If the irradiance is 1 kw/m2, what
is the photon flux?
10.2. When the energy flux density in the 400 to 700 nm waveband is
200 w/m2, what is the photon flux density of PAR (mol m-2 s-I)?
10.3. When photon flux density is 1000 pmol mW2 s-I in the 400 to
700 nm waveband, what is the energy flux density (w/m2) in the
PAR waveband? What is the flux density of solar radiation (all
wavelengths)?
10.4. What is the wavelength ofpeak emittance for a 2800 K incandescent
light bulb?
10.5. If your mean surface temperature is 28" C, what is your emittance?
If the mean wall temperature in the room in which you are standing
is 20" C, what is the average thermal irradiance at your surface?
Estimate your net radiant heat loss. Assume
= 0.97 and &, l l =
1.0.
10.6. Compare the radiant emittance of a clear sky and a completely
overcast sky, both at 0' C. How much additional radiant energy
does the ground receive on an overcast night?