Foil chaff clouds as a tool for in-situ measurements of atmospheric motions in the middle atmosphere: their flight behaviour and implications for radar tracking

The aerodynamic behaviour of foil chaff (rectangular plates) used for in-situ measurements of atmospheric motions in the middle atmosphere (up to 100 km altitude) can be described by Stokes' Law in which the corrections are applied to the coefficient of viscosity. The results obtained with this approximation are in good agreement with observations and allow us to explain in detail certain peculiarities occasionally seen in the tracking of chaff clouds by radar.