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- Author or Editor: Earl W. Barrett x
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Abstract
Following a brief review of the assumptions involved in the usual (Laplacian) expression for the speed of sound waves, an instrument, the sonic thermometer, is described which utilizes this relationship to measure the air temperature. The advantages of the sonic thermometer are then discussed, the main advantages being the absence of radiational errors and extremely low lag—a result of the fact that the measured variable, the speed of sound, is independent of the properties of the measuring elements.
Abstract
Following a brief review of the assumptions involved in the usual (Laplacian) expression for the speed of sound waves, an instrument, the sonic thermometer, is described which utilizes this relationship to measure the air temperature. The advantages of the sonic thermometer are then discussed, the main advantages being the absence of radiational errors and extremely low lag—a result of the fact that the measured variable, the speed of sound, is independent of the properties of the measuring elements.
Abstract
An urgent need exists for a technique of rapid and economical measurement of vertical profiles of atmospheric particulate concentration. It is shown in this paper that the lidar, or optical radar, is capable of meeting this need. The first part of the paper presents the physical basis of the technique wherein equations based on the Mie scattering theory and the radar equation are derived which permit quantitative calculation of the particulate concentration, turbidity index, and horizontal visibility from the lidar data as functions of height. The remainder of the paper is devoted to a brief description of an operational lidar system, some examples of results obtained with it, and an evaluation of its performance during six months of use. A subsequent paper will present some detailed case studies of pollution episodes in the Chicago Metropolitan area.
Abstract
An urgent need exists for a technique of rapid and economical measurement of vertical profiles of atmospheric particulate concentration. It is shown in this paper that the lidar, or optical radar, is capable of meeting this need. The first part of the paper presents the physical basis of the technique wherein equations based on the Mie scattering theory and the radar equation are derived which permit quantitative calculation of the particulate concentration, turbidity index, and horizontal visibility from the lidar data as functions of height. The remainder of the paper is devoted to a brief description of an operational lidar system, some examples of results obtained with it, and an evaluation of its performance during six months of use. A subsequent paper will present some detailed case studies of pollution episodes in the Chicago Metropolitan area.
Abstract
After a theoretical discussion of the basic physical principles involved in the dew-point method of hygrometry, which serves to establish the inherent advantages of the technique, the paper describes the operating principles and the design of an improved, automatic, electronic dew-point hygrometer for laboratory or field use. The instrument makes use of photoelectric detection of condensation on a cooled, polished metal mirror combined with a radio-frequency induction heating system and an all-electronic proportional heat-control servo system. The instrument makes possible the continuous and automatic measurement of atmospheric water-vapor under all conditions of temperature with nearly constant accuracy and small lag.
Abstract
After a theoretical discussion of the basic physical principles involved in the dew-point method of hygrometry, which serves to establish the inherent advantages of the technique, the paper describes the operating principles and the design of an improved, automatic, electronic dew-point hygrometer for laboratory or field use. The instrument makes use of photoelectric detection of condensation on a cooled, polished metal mirror combined with a radio-frequency induction heating system and an all-electronic proportional heat-control servo system. The instrument makes possible the continuous and automatic measurement of atmospheric water-vapor under all conditions of temperature with nearly constant accuracy and small lag.
Abstract
The electronic dew-point hygrometer described by Barrett and Herndon in 1951 has been improved in three distinct areas: the servo-amplifier system, the optical system in the sensing head, and the operating-adjustment system. The improvements are described, and the operational use of the improved hygrometer is discussed briefly.
Abstract
The electronic dew-point hygrometer described by Barrett and Herndon in 1951 has been improved in three distinct areas: the servo-amplifier system, the optical system in the sensing head, and the operating-adjustment system. The improvements are described, and the operational use of the improved hygrometer is discussed briefly.
