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  • Author or Editor: F. J. Lourence x
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F. J. Lourence
and
Wilson B. Goddard

Abstract

The water level in a sump of a 6.1 m diameter floating lysimeter tank is measured by a linear-variable differential transformer. The transducer output representing weight changes of the floating tank is recorded continuously on a strip-chart recorder. An automatic-range switching device enables the system to have a sensitivity of 0.025 mm of water level through a range of 9.15 cm. Floating lysimeter evapotranspiration totals measured by this system agree well with the weight records of a scale-type weighing lysimeter of dimensions operating close by.

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F. J. Lourence
and
W. O. Pruitt

Abstract

An aspirated psychrometer system using thermopiled copper-constantan sensors is described. Field data are presented showing temperature and humidity profiles obtained over a turf crop by nine self-contained units mounted on a 6 m mast. Temperature and humidity can be determined with accuracies of 0.025C and 0.15 mm Hg vapor pressure.

The units are relatively inexpensive and easy to fabricate. The wet-bulb element, a porous ceramic cup supplied with a continuous column of water from a reservoir, provides more reliable and less critical operation than the conventional cotton-wick elements.

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D. L. Morgan
,
W. O. Pruitt
, and
F. J. Lourence

Abstract

Various methods of estimating atmospheric radiation including the use of radiation charts and six empirical formulas are examined, using micrometeorological data collected at Davis, Calif. The Bolz method for adjusting the clear-sky estimates of atmospheric radiation from empirical formulas for cloudy, conditions is studied using observed cloud conditions and measured atmospheric radiation. This method works well for overcast low-cloud conditions. However, in high-cloud conditions with less than complete sky coverage, it is less satisfactory, perhaps due to problems in analytically representing the cloud conditions.

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