In the present Letter we use the Direct Numerical Simulation (DNS) of the
Navier-Stokes equation for a two-phase flow (water and air) to study the
dynamics of the modulational instability of free surface waves and its
contribution to the interaction between ocean and atmosphere. If the steepness
of the initial wave is large enough, we observe a wave breaking and the
formation of large scale dipole structures in the air. Because of the multiple
steepening and breaking of the waves under unstable wave packets, a train of
dipoles is released and propagate in the atmosphere at a height comparable with
the wave length. The amount of energy dissipated by the breaker in water and
air is considered and, contrary to expectations, we observe that the energy
dissipation in air is larger than the one in the water. Possible consequences
on the wave modelling and on the exchange of aerosols and gases between air and
water are discussed
