Vaisala RAINCAP® Technology
Vaisala RAINCAP® Sensor is an acoustic sensor that measures the impact of individual raindrops on a smooth stainless steel surface using a piezoelectric detector. The sensor provides real time information on rain intensity, duration, and accumulated rainfall.
How it works
The RAINCAP® sensor consists of a round stainless steel cover, approximately 90 mm in diameter mounted to a rigid frame. A piezoelectric detector is located beneath the cover. Raindrops hit the RAINCAP® sensor surface at terminal velocity, which is a function of the raindrop diameter. Rain measurement is based on acoustic detection of each individual rain drop as it impacts the sensor cover. Larger drops create a larger acoustic signal than smaller drops.
The piezoelectric detector converts the acoustic signals into voltages. Total rain is calculated from the sum of the individual voltage signals per unit time and the known surface area of the RAINCAP® sensor. In addition, the intensity and duration of rain can be calculated.
The RAINCAP® sensor can also distinguish between hail and raindrops. The acoustic signature of hail is markedly different from that of rain and is easily detected. The RAINCAP® sensor reports intensity, duration, and accumulation of hail.
The RAINCAP®sensor has been tested extensively at different sites in temperate and tropical locations. Comparisons made to tipping bucket gauges and weighingrecording gauges validate the measurement performance of the RAINCAP® sensor. See figures 3 and 4 for comparison data.
There is no obvious measurement accuracy advantage to any specific rain measurement method, but there are several unique advantages to the RAINCAP® technology.
- First, the RAINCAP® requires virtually no maintenance, therefore it is suitable for remote locations.
- Second, the RAINCAP®provides precipitation data in real time.
- Third, the RAINCAP®can distinguish between rain and hail and provide data for both types of precipitation.
Products using RAINCAP® Technology
Weather Transmitter WXT530 Series
