Present weather detector
The Vaisala PWD21 present weather detector at Chilbolton Observatory provides continuous, unattended reports of weather conditions. It uses the forward scattering of a light beam between two offset terminals to measure visibility and a capacitative rain sensor to quantify precipitation. It combines these measurements with those of ambient temperature to report current weather conditions and those over the last hour using both NWS and WMO weather codes. The instrument provides valuable supporting information for other measurements at the site.
The present weather detector was deployed at Sparsholt College from 2005 to 2007 and at Chilbolton from 2009 to 2015.