The cold vertical closed circuit wind tunnel is 7.9 m heigh and 3.2 wide, cross section is 0.4 m times 0.4 m which can be reduced in the working leg. The air velocity, inside the tunnel, can be set between 2 and 30 m/s, and the lowest working temperature is about -25°C. On the bottom of the tunnel is placed an inlet of droplets, generated by an outside droplets sprayer. The injected droplets, in a short time, come to thermal equilibrium with the tunnel air temperature and are therefore supercooled. In the upper part of the tunnel is located the working leg (80 cm height). In the working leg several experiments can be designed such as: ice accretion experiments on a rotating pivot, ice growth on plane wings, et.. It is therefore possible to perform tests on groupels from icing of supercooled droplets simulating the processes wich makes hail inside clouds. By changing the operating parameters (air temperature and velocity, water liquid content, et..) it is possible to obtain ice accretion with different properties and morphologies. In the same way tests on wings can be performed simulating airplanes flying through clouds containing supercooled droplets and ice crystals.