A new astrophysics activity at Nordita focusses on the calculation of the stochastic gravitational wave (GW) background. Specifically, we determine, using numerical simulations and analytical approach, the strengths of the resulting GW field at the present time for a range of GW sources associated with turbulent stresses in the energy-momentum tensor. Another activity concerns the interaction of particles with turbulence and the growth of cloud droplets. This activity is supported by a grant on Bottlenecks for the growth of particles suspended in turbulent flows (Knut & Alice Wallenberg Foundation, with Professor Mehlig from Gothenburg as PI).