Snow permittivity measurement for avalanche forecasting - uses probes for measurement at two frequencies with thermistor for temp. determination to calculate water content of snow

摘要

Measurement of permittivity of snow at two different frequencies together with temperature measurement enables avalanche risk to be forecast. Probes with electronic measurement and control circuits are arranged at particular depths in snow. Each probe contains a thermistor in a bridge circuit with a potentiometer and galvanometer permitting direct reading of snow temperature. Permittivity is measured by connecting a measuring capacitor and balancing capacitor to two oscillators in turn. A motor varies the balancing capacitor for balance on the galvanometer connected to discriminator outputs. The motor also drives a potentiometer producing a voltmeter reading which enables density and water content to be determined.