  In this work we designed and developed a cluster of light expendable
radiosondes that can float passively inside warm clouds to study their
micro-physical processes. This involves the tracking of both saturated and
unsaturated turbulent air parcels. The aim of this new kind of observation
system is to obtain Lagrangian statistics of the intense turbulence inside warm
clouds and of the lower intensity turbulence that is typical of the air
surrounding such clouds. Each radiosonde in a cluster includes an electronic
board, which is mounted onto a small, biodegradable balloon filled with a
mixture of helium and air. The cluster is able to float inside clouds for a few
hours and to measure air temperature, pressure, humidity and the associated
position, velocity, acceleration and magnetic field readings of each radiosonde
along their trajectory.
