The hydrodynamics of processes occurring in explosion of condensed explosives in air at some height above the ground surface is considered. The computation technique, physical model, and results of simulation of a two-dimensional hydrodynamic flow arising in explosion of cylindrical charges are discussed. For the description of products of explosion the Jones-Wilkins-Lee equation of state is used. The explosions of charges with different mass (0.5, 5, 50 kg TNT) are considered. The results of calculation allow one to obtain a detailed space-time picture of the arising flow and to study the origination, propagation, interaction and subsequent attenuation of shock waves. It is shown that the interaction of secondary and reflected from surface shock waves can strongly influence on the dynamics of flow. (C) 2010 Published by Elsevier Ltd.