Back to product search

Vaisala PWD22 Present Weather Detector

Vaisala PWD22 present weather detectors and visibility sensors provide an accurate and reliable measurement of prevailing visibility. Vaisala have a strong pedigree in weather monitoring instrumentation, thousands of the PWD22 present weather and visibility sensors are installed globally in diverse applications and climates. Vaisala PWD22 present weather detectors provide the mix you require of visibility
measurement range (MOR), characterisation of reduced visibility, precipitation type identification, precipitation accumulation/intensity
measurement, and report formats (WMO, NWS code tables).


Vaisala PWD22 Present Weather Detector Specifications:

  • Operating principle: Forward scatter measurement with 45° scattering angle
  • Observation range of MOR 10 … 20 000 m (32 … 65 600 ft)
  • Accuracy ±10 % at 10 … 10 000 m (32 … 32 800 ft) ±15 % at 10 … 20 km (2.6 … 12 mi)
  • Weather type identification 7 different types of precipitation (rain, freezing rain, drizzle, freezing drizzle, mixed rain/snow, snow, ice pellets), Precipitation (unknown type), Fog (mist), haze (smoke, sand) or clear
  • Weather type reporting WMO 4680 (SYNOP), 4678 (METAR) and NWS code tables; 49 different codes supported from WMO 4680 code table
  • Precipitation detection sensitivity 0.05 mm/h (0.0020 in/h) or less, within 10 minutes
  • Precipitation intensity measurement 0.00 … 999.99 mm/h (0.00 … 39.37 in/h)
  • Precipitation amount measurement 0.00 … 99.99 mm (0.00 … 3.94 in)
  • Amount of new snow 0.00 … 999 mm (0.00 … 39.33 in)
  • Power supply 12 … 50 VDC (electronics) 24 VAC or 24 VDC for heater option
  • Average power consumption: 3 W (peak 10 W), With optional luminance sensor: 5 W, With optional hood heaters: 65 W
  • Outputs Serial data line may be used either asRS‑232 or RS‑485 (2‑wire) level signals
    3 relay controls (open collector)
    Analog output current: 0 … 1 mA or 4 … 20 mA
    8-m power/data cable standard. (The PWD end is equipped with connector).
  • Auxiliary data Low visibility alarms in the data messages. 3 adjustable alarm limits to set the 3 relay controls. Hardware status (fail/warning) in the data messages. Third relay control output can also be driven by hardware status.


Proven measurement principles for Vaisala PWD22 identify precipitation type by accurately estimating the water content of precipitation with a capacitive device (Vaisala RAINCAP® sensor element) and combining this information with optical forward scatter and temperature measurements. These three independent measurements are processed through sophisticated algorithms in order to produce an accurate evaluation of the weather type according to the WMO and NWS code tables.

Vaisala PWD22 sensors use the proven forward scatter measurement principle to measure meteorological optical range (MOR). The visibility sensor is well protected against contamination: the optical components point downwards and hoods protect the lenses against precipitation, spray, and dust.  This weather-proof design of Vaisala PWD22 sensors provides accurate measurement results and reduces the need for maintenance. The optional hood heaters are recommended for wintry conditions to prevent ice and snow accumulation.

Vaisala PWD22 Present Weather Detector sensors are less than one meter long. It is a compact, light-weight instrument that comes with a cable and connector for easy installation, and can be mounted in many ways on any existing mast.


Fluidic are a recognised distributor of Vaisala MetOcean instrumentation for Scotland and the North of England.  Our instrumentation engineers are product trained and able to help with instrument selection within the full range of Vaisala instrumentation.  Please call either office for more information (Glasgow 0141 641 5920,  Warrington 01925 572401).


Enquire about this product
Your Name *
Please call either office for more information: