SMALL SENSITIVE ANEMOMETER SYSTEM FOR AGRICULTURAL METEOROLOGY

The paper describes a cup anemometer system suitable for use close to the ground and within crop canopies. The anemometers are small, sensitive, weatherproof, rugged and sufficiently inexpensive to be constructed in array proportions. The anemometer is about 6 cm high and the rotor arms about 6 cm long. The counting mechanism employs an automobile lamp whose voltage is stabilized by a Zener diode, a light-chopper unit, a CdS photocell and a highspeed electromagnetic counter. Details of the design, construction, circuitry and field use of the system are discussed. Starting speeds of the anemometers are between 10 and 15 cm/sec. The design of the anemometers is such that uniformity between different batches is high. Twelve prototype instruments had almost identical calibration curves, within ± 1% of the mean over a range 2-8 m/sec. © 1969.