Theory 72/Measurement & modelling/Rain gauges
Gauge Error Is Wind Against Exposure
The claim
Rain gauge undercatch is set by the ratio of wind speed to gauge orifice shielding, so exposed gauges underreport snowfall by a large and systematic margin.
01Mechanism
Wind deflects particles around the orifice; shielding reduces the deflection.
02Prediction
Undercatch should track the ratio.
03Refutation
Undercatch tracking rainfall intensity would remove wind.