Leaf and Canopy Temperature
An infrared thermometer measures radiant energy. This radiation is simply “light” that is slightly outside the human eye’s sensitive range. All objects radiate infrared energy. The intensity of infrared radiation is proportional to the absolute temperature (°K Kelvin) of the object. Infrared thermometers produce no “intrusion error.” A hot object “target” is radiating its infrared radiation in all directions. The object’s radiation characteristics, and hence its temperature, are not disturbed by the presence of the infrared thermometer. The infrared thermometer optics collect a sample of infrared radiation from the hot object (soil & plant) being measured and focus it on the tiny infrared detector. The detector, in turn, converts it to a proportional electrical signal, which is the exact electrical analog of the incoming infrared radiation, and hence the hot object’s temperature. This minute electrical signal is then amplified, converted to a digital signal, and digitally linearized and the resultant temperature either displayed or data logged. Low temperature infrared thermometry (IRT) is technically quite difficult especially when measuring temperatures of crop canopies which have a very weak infrared signal and temperatures are needed to be resolved to 0.1 Deg C to make meaningful irrigation and management decisions. Continuous measurement of the transducer temperature and sky reflectance of infrared light must be undertaken. Accurate measurements of plant canopy temperature, which, along with other environmental variables, allows estimation of canopy transpiration and crop stress using a calculation such as Crop Water Stress Index (CWSI).
For Apogee SI-400 Series information and Field of View (FOV) options, see the product link here.
The MFR-NODE (LoRaWAN or CATM1/NB-IoT) supports up to 2 x SI-400 Series Radiometers
The S-NODE (LoRaWAN or CATM1/NB-IoT) supports up to 4 x SI-400 Series Radiometers