The Rainfall Sensor is mounted in U.V stable plastic and is aerodynamically shaped to reduce the effects of wind. The rain is collected by a funnel having an outer diameter of 80mm, therefore, 5ml of rain water will represent 1mm of rainfall.
The Rainfall Sensor measures the amount of rainfall passing through it by means of an infra-red optical system.

The sensor is manufactured from anodised aluminium with a laboratory glass dome. The unit is fully sealed against the ingress of moisture and sturdily built to withstand the most adverse weather.
Comparing direct sunlight with shade the sensor produces a pulse every 36 seconds (0.01 hour) when the ratio exceeds a certain pre-set level ensuring that the output is independent of time of day or season, giving excellent results within a few minutes of dawn or dusk.

The combined Wind Speed and Direction Sensor is manufactured from anodised aluminium alloy, UPVC and stainless steel with moulded polypropylene cups. 
Wind Direction is sensed by a precision conductive plastic potentiometer which provides exceptional accuracy and high sensitivity.
Wind Speed is derived from a Hall Effect solid state magnetic switch activated by magnets in the cup rotor running in precision stainless steel ball race providing very high senstivity.