Apogee Instruments SF-110 Benutzerhandbuch - Seite 4
Blättern Sie online oder laden Sie pdf Benutzerhandbuch für Sicherheitssensoren Apogee Instruments SF-110 herunter. Apogee Instruments SF-110 17 Seiten. Radiation frost detector
Seite druckenINTRODUCTION
In January 2022, the SF-110 (formerly called the leaf and bud temperature sensor) underwent a redesign to improve
performance and ruggedness. As part of this redesign, the bud temperature sensor was removed, as it was determined the
leaf measurement was most critical. The SF-110 was renamed the radiation frost detector.
Frost damage to plants can have a large impact on crop yield and quality. Protection of crops during frost events is
dependent on the accuracy of plant temperature predictions. Often, air temperature is not a reliable predictor of
timing, duration, and severity of frost events because plant canopy temperatures can be significantly different
than air temperature under certain environmental conditions.
On clear, calm nights, plant leaf temperature can drop below freezing even if air temperature remains above 0 C
(see figure on page 5). This is called a radiation frost and is caused by the lack of air mixing (wind) near the surface
and a negative net longwave radiation balance at the surface (more longwave radiation is being emitted from the
surface than what the surface is absorbing from the clear sky). Under cloudy and/or windy conditions, radiation
frost events do not occur.
Apogee model SF-110
radiation frost detectors are designed to approximate plant leaf temperatures for prediction
of frost
events. SF-110
radiation frost detectors are intended for applications in cropped fields and orchards when
air temperatures will be near freezing and where air
temperature measurements are not a good predictor of frost
formation.
Apogee Instruments SF-110 radiation frost detectors consist of a precision thermistor combined with a simulated
leaf. The sensor is designed to mimic a plant leaf. SF-110 radiation frost detectors provide close approximations of
leaf temperature and can be used to predict frost on leaves. The detector is weatherproof and designed for
continuous temperature measurement in the same environmental conditions to which plants are exposed. The SF-
110 detector outputs one analog voltage signal (when supplied with an input voltage) that is related to the
resistance of a thermistor. The resistance is directly related to simulated leaf temperature.