184
Radiation Fluxes in Natural Environments
Gates, D. M. (1980) Biophysical Ecology. New York: Springer Verlag.
Hall, F.G., K.F. Huemmerich, D.E. Strebel, S.J. Goetz, J.E. Nickeson,
and K.D. Woods, (1992) Biophysical, Morphological, Canopy Optical
Property, and Productivity Data From Superior National Forest. NASA
Tech. Mem. 104568, Goddard Space Flight Center, Greenbelt, MD 2077 1.
List, R. J. (197 1) Srnithsonian Meterological Tables, 6th ed. Washington D. C.: Smithsonian Institution Press.
Liu, B. Y., and R. C. Jordan (1960) The interrelationship and characteristic distribution of direct, diffuse, and total solar radiation. Solar
Energy 4: 1-19.
McCullough, E. C., and W. P. Porter (1971) Computing clear day
solar radiation spectra for the terrestrial ecological environment. Ecology
52:1008-1015
Monteith, J. L. and M. H. Unsworth (1 990) Principles of environmental
Physics, second edition. London: Edward Arnold.
Mum, R. E. (1966) Descriptive Micrometerology. New York: Academic Press.
Peterson, W. A., and I. Dirmhirn. (1981.) The ratio of diffuse to direct
solar irradiance (perpendicular to the sun's rays) with clear skies - a
conserved quantity throughout the day. J. Appl. Meteorol. 20:826-828.
Weiss, A. and J. M. Norman. (1985.) Partitioning solar radiation into
direct and diffuse, visible and near-infrared components. Agric. Forest.
Meteorol. 34:205-213.
Problems
1 1.1. Compare Rabs for an animal under a clear night sky and a completely
overcast cloudy night sky. Assume T, = Tg = 20" C.
11.2. Compute Rabs for your hand suspended horizontally over a dry
soil surface on a clear day. Assume T, = 25" C, T, = 45" C, yf = 40°,
and q = 0.65. Estimate values not given and state assumption
for making estimates Estimate the total watts absorbed by your
hand.
11.3. Give all components of the radiant energy budget, and compute the
net radiation for a bare soil surface under a clear sky on April 10 at
1100 hrs. solar time. Latitude is 37" and elevation is 1200 m. Air
temperature is 18" C and soil surface temperature is 22" C.
1 1.4. Make the same computations as in problem 1 1.3, but for an overcast
sky.
11.5. Find the elevation, zenith, and azimuth angles of the sun at 600 hrs
(solar time) on June 2 1, at a latitude of 48" and longitude of 95".
11.6. Find the daylength and time of sunrise and sunset using the data in
problem 1 1.5.
11.7. Estimate the duration of civil twilight in hours for Example 1 1.1.
Radiation Fluxes in Natural Environments
Gates, D. M. (1980) Biophysical Ecology. New York: Springer Verlag.
Hall, F.G., K.F. Huemmerich, D.E. Strebel, S.J. Goetz, J.E. Nickeson,
and K.D. Woods, (1992) Biophysical, Morphological, Canopy Optical
Property, and Productivity Data From Superior National Forest. NASA
Tech. Mem. 104568, Goddard Space Flight Center, Greenbelt, MD 2077 1.
List, R. J. (197 1) Srnithsonian Meterological Tables, 6th ed. Washington D. C.: Smithsonian Institution Press.
Liu, B. Y., and R. C. Jordan (1960) The interrelationship and characteristic distribution of direct, diffuse, and total solar radiation. Solar
Energy 4: 1-19.
McCullough, E. C., and W. P. Porter (1971) Computing clear day
solar radiation spectra for the terrestrial ecological environment. Ecology
52:1008-1015
Monteith, J. L. and M. H. Unsworth (1 990) Principles of environmental
Physics, second edition. London: Edward Arnold.
Mum, R. E. (1966) Descriptive Micrometerology. New York: Academic Press.
Peterson, W. A., and I. Dirmhirn. (1981.) The ratio of diffuse to direct
solar irradiance (perpendicular to the sun's rays) with clear skies - a
conserved quantity throughout the day. J. Appl. Meteorol. 20:826-828.
Weiss, A. and J. M. Norman. (1985.) Partitioning solar radiation into
direct and diffuse, visible and near-infrared components. Agric. Forest.
Meteorol. 34:205-213.
Problems
1 1.1. Compare Rabs for an animal under a clear night sky and a completely
overcast cloudy night sky. Assume T, = Tg = 20" C.
11.2. Compute Rabs for your hand suspended horizontally over a dry
soil surface on a clear day. Assume T, = 25" C, T, = 45" C, yf = 40°,
and q = 0.65. Estimate values not given and state assumption
for making estimates Estimate the total watts absorbed by your
hand.
11.3. Give all components of the radiant energy budget, and compute the
net radiation for a bare soil surface under a clear sky on April 10 at
1100 hrs. solar time. Latitude is 37" and elevation is 1200 m. Air
temperature is 18" C and soil surface temperature is 22" C.
1 1.4. Make the same computations as in problem 1 1.3, but for an overcast
sky.
11.5. Find the elevation, zenith, and azimuth angles of the sun at 600 hrs
(solar time) on June 2 1, at a latitude of 48" and longitude of 95".
11.6. Find the daylength and time of sunrise and sunset using the data in
problem 1 1.5.
11.7. Estimate the duration of civil twilight in hours for Example 1 1.1.