An Improved Humidity Sensor

Pang, Shixuan; Graßl, Hartmut; Jäger, H.

doi:10.1175/1520-0426(1996)013<1110:aihs>2.0.co;2

Cited by 4 publications

(3 citation statements)

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“…Anderson suggests that this is because a thin film of noncrystalline water is formed on the sensor material. Pang et al (1996) found a small discontinuity in the sensor response at about 228C while keeping humidity constant at 97% RH, probably a result of a small portion of the water molecules forming ice crystals. Capacitive sensors are used in many automated weather stations (AWSs) and in many modern radiosondes.…”

Section: Capacitive and Other Absorption/adsorption Sensorsmentioning

confidence: 98%

“…The saturation vapor pressure e s (hPa) was calculated from temperature T (8C) as 3 Pang et al (1996) looked at the hysteresis of capacitive sensors and suggested a way of almost eliminating it. 4 The enhancement factor is the ratio of the saturated vapor pressure of water in moist air to the saturated vapor pressure of pure water.…”

Section: Camborne Trial: Descriptionmentioning

confidence: 99%

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Evolution and Accuracy of Surface Humidity Reports*

Ingleby

Moore

Sloan

et al. 2013

Journal of Atmospheric and Oceanic Technology

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Until recently surface humidity was predominantly measured using psychrometers (wet-and dry-bulb thermometers). In some countries, often in conjunction with increased automation, the measurement technique has changed-usually to capacitive sensors. The scale of the change in instrumentation and the error characteristics of the operational instruments have not been well documented. This paper provides an overview of these operational instruments and their error characteristics, intended to be useful for climate and forecast users of the data. It also includes detailed results from comparisons of psychrometers and capacitive sensors with a chilled mirror reference instrument at a site in the United Kingdom under (near) operational conditions. The psychrometers performed well near saturation but underread at lower humidities; any large errors tended to be positive because of insufficient water supply to the wet bulb. New capacitive sensors perform well but they usually drift to higher values during deployment (except in arid climates); they perform best at lower humidities and need regular adjustment and recalibration. The natural variation of relative humidity and the differences between instruments are larger in daytime than at night. Changes in the U.K. synoptic network are described in order to put the intercomparisons into context. The instruments used in selected other countries are surveyed. There is a need for better documentation and real-time exchange of metadata on the instruments used and any changes. Capacitive sensors are also used on some radiosondes and aircraft; relevant studies are briefly reviewed and some parallels with surface usage are drawn.

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Section: Capacitive and Other Absorption/adsorption Sensorsmentioning

confidence: 98%

Section: Camborne Trial: Descriptionmentioning

confidence: 99%

Evolution and Accuracy of Surface Humidity Reports*

Ingleby

Moore

Sloan

et al. 2013

Journal of Atmospheric and Oceanic Technology

View full text Add to dashboard Cite

show abstract

“…CPU as the control center [16][17][18] is also the most important part. The CPU directly reflects the functions and main features of the single chip microcomputer, and executes commands and operations.…”

Section: Cpu Structurementioning

confidence: 99%

Temperature and Humidity Control System of Vegetable Greenhouse Based on Single Chip Computer

2022

DPS

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It changes all year round. In the north, in order to satisfy the public's desire to eat fresh vegetables in winter, vegetable greenhouses came into being. With the rapid development of society, people have put forward higher and higher requirements for the quality of vegetables. The temperature and humidity of the greenhouse have a great influence on the quality of vegetables. Therefore, in order to ensure the quality of vegetables, the temperature and humidity of the greenhouse must be kept within the range most suitable for the growth of vegetables. Therefore, the design of the temperature, room temperature and humidity control system are particularly important. The temperature and humidity control system based on single-chip microcomputer designed in this paper monitors and tempers the greenhouse temperature in real time through the DS18B20 and DHT11 temperature and humidity sensors, respectively, and displays the monitoring results on the liquid crystal display. The single chip microcomputer adjusts the greenhouse temperature and humidity through the monitoring results In order to keep the temperature and humidity of the greenhouse in a constant range. The temperature control system in this paper can achieve a measurement accuracy of ± 0.3 ℃ and a display accuracy of 0.1 ℃. It can also manually adjust the temperature and humidity within a certain range to suit the growth conditions of different vegetables. The results show that the temperature measurement system has the characteristics of high accuracy, high sensitivity, stable operation and so on, which meets the performance requirements of the design. It is a reliable digital temperature measurement control system.

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Methodology for the independent calibration of Raman backscatter water-vapor lidar systems

1999

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We present a method for the independent calibration of Raman backscatter water-vapor lidar systems. Particular attention is given to the resolution of instrumental changes in the short and the long terms. The method reposes on the decomposition of the instrument function, which allows the lidar calibration coefficient to be re-expressed as the product of two terms, one describing the instrumental transmission and detection efficiency and the other describing the wavelength-dependent convolution of the Raman backscatter cross sections with the instrument function. The origins of changes in instrument response necessitate the experimental determination of the system detection efficiency. Two external light sources for calibration are assessed: zenith observation of diffuse sunlight and a xenon arc lamp. The results favor use of the diffuse-sunlight measurement but highlight the need for simultaneous sunphotometer measurements to constrain modeled aerosol optical properties. Quantum mechanical models of the Raman cross sections are described, and errors in determining the cross sections and their convolution with the instrument function are discussed in detail. The calibration coefficients deduced by using the independent method are compared with coefficients deduced from Vaisala H-Humicap radiosonde measurements. These results agree to within current calibration errors (15%, unconstrained aerosol parameters), and a change in calibration coefficient following instrument modification is reproduced satisfactorily. Results from modeling and intercomparison studies are extended to estimate the calibration accuracy and the precision of the diffuse-sunlight method with constrained modeled aerosol parameters. Changes in the calibration coefficient in the short and the long terms should be resolved to 4(6)% and 6(9)%, respectively, which is comparable or better than the precision of existing dependent methods of calibration. The reduction of the absolute calibration error remains an outstanding issue for all calibration methods.

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An Improved Humidity Sensor

Cited by 4 publications

References 0 publications

Evolution and Accuracy of Surface Humidity Reports*

Evolution and Accuracy of Surface Humidity Reports*

Temperature and Humidity Control System of Vegetable Greenhouse Based on Single Chip Computer

Methodology for the independent calibration of Raman backscatter water-vapor lidar systems

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