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  • Long-wave radiation at the ground: II. Geometry of interception by slopes, solids, and obstructed planes

    Creator:
    Unsworth, Michael H.
    Abstract:
    At the earth's surface, long‐wave radiation received from the atmosphere in the absence of cloud may be expressed as the sum of the flux density from an isotropic source and the flux density due to anisotropy of atmospheric radiation. Separation of these components facilitates calculations of the radiative flux received...
    Resource Type:
    Article

  • Spectral distribution of solar radiation. I: direct radiation

    Creator:
    McCartney, H. A. and Unsworth, Michael H.
    Abstract:
    Measurements of the spectral distribution of direct solar radiation, made in both wide and narrow wavebands, are reported. The measurements suggest that the wavelength dependence of aerosol attenuation in central England, in summer, can generally be described by a power law with wavelength exponent of about 1.7. Attenuation of visible...
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    Article
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    : direct radiation By H. A. McCARTNEY* and M . H. UNSWORTH Department of Physiology and Environmental

  • Turbulent transfer of sulphur dioxide to a wheat crop

    Creator:
    Fowler, D. and Unsworth, Michael H.
    Abstract:
    Fluxes of sulphur dioxide to wheat were measured over two growing seasons. The deposition velocity, vg, depended primarily on affinities of surfaces for SO2 and varied from less than 0.1 to about 1.5cms−1. Stomata were an important sink, and diurnal changes in stomatal resistance accounted for most of the variation...
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    Article
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    wheat crop By D. FOWLER* and M. H. UNSWORTH Environmental Physics Unit, School of Agriculture

  • Some aerodynamic features of a cotton canopy

    Creator:
    Bache, D.H. and Unsworth, Michael H.
    Abstract:
    Analysis of profiles measured over irrigated cotton in the Sudan Gezira showed that the crop boundary layer remained stable throughout most of the day. The shape of wind profiles measured within the canopy suggested that momentum was absorbed mostly in the upper layers of the canopy, with the lower regions...
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    Article
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    cotton canopy By D. H. BACHE* and M. H. UNSWORTH Nottingham University, School of Agriculture

  • Longwave radiation at the ground: IV. Comparison of measurement and calculation of radiation from cloudless skies

    Creator:
    Dalrymple, G.J. and Unsworth, Michael H.
    Abstract:
    On cloudless days in summer, longwave irradiance was measured with a radiometer and was calculated from a radiation chart using records from radiosondes released at regular intervals. The results show that the chart underestimated the longwave flux density at the ground by up to 40W/m^(-2), corresponding to an extra atmospheric...
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    from cloudless skies By G. J. DALRYMPLE and M. H. UNSWORTH University of Nottinghatn. School of

  • Long-wave radiation at the ground

    Creator:
    Unsworth, Michael H. and Monteith, J.L.
    Abstract:
    The apparent emissivity of the atmosphere ϵ, defined as the ratio of incoming long-wave radiation to black-body radiation at screen temperature Tₐ, was measured under clear skies in the English Midlands and in the Sudan. At a zenith angle Z the emissivity was given by ϵ(Z) = a + bIn(usec...
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    ground I. Angular distribution of incoming radiation By M. H. UNSWORTH and J. L. MONTEITH University

  • The diffuse solar irradiance of slopes under cloudless skies

    Creator:
    Steven, M. D. and Unsworth, Michael H.
    Abstract:
    The diffuse irradiance of slopes relative to the diffuse irradiance of a horizontal surface is calculated by integrating the mean radiance distributions of cloudless skies in Britain for a wide range of solar elevations, azimuths and slope angles. There is reasonable agreement with measurements reported from a number of stations;...
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    Article
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    of slopes under cloudless skies By M. D. STEVEN and M. H. UNSWORTH Environmental Physics Unit

  • Effects of aerosol on the local heat budget of the lower atmosphere

    Creator:
    Glazier, J., Monteith, J.L., and Unsworth, Michael H.
    Abstract:
    The convergence of heat below subsidence inversions was estimated from radiosonde ascents on fine summer days. Sensible heat input from the ground was estimated from measurements of heat fluxes and net radiation over a wheat field. Absorption and back scattering of solar radiation by aerosol throughout the atmosphere were calculated...
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    heat budget of the lower atmosphere By J. GLAZIER, J. L. MONTEITH and M. H. UNSWORTH University of

  • Shade-ring corrections for pyranometer measurements of diffuse solar radiation from cloudless skies

    Creator:
    Steven, M. D. and Unsworth, Michael H.
    Abstract:
    When a shade ring is used to shield a pyranometer from direct solar radiation, a correction to the measured diffuse radiation is necessary to account for diffuse radiation intercepted by the ring. A general analysis is developed to relate shade-ring corrections to the radiance distribution of diffuse radiation. The corrections...
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    Article
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    skies By M. D. STEVEN and M. H. UNSWORTH Eiivironmental Physics Unit, University of Norringham

  • The angular distribution and interception of diffuse solar radiation below overcast skies

    Creator:
    Steven, M. D. and Unsworth, Michael H.
    Abstract:
    The angular distribution of diffuse radiation was measured from May 1976 to May 1977 with a set of purpose-built actinometers. Radiance distributions for 98 overcast hours were fitted well by an expression similar to the conventional function for a 'standard overcast sky' (SOC). However, values of the coefficient b averaged...
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    and M. H. UNSWORTH Environmental Physics Unit, University of Nottingham School of Agriculture