Wind turbines packed in large offshore wind farms hinder each other by the formation of turbulent wind wakes, which lead to large efficiency losses at downstream turbines. With the growing number and attention for wind farms, it becomes clear that the wake effect is not only present on a turbine-to-turbine level, but also on a farm-to-farm level. On a wind farm level the energy extraction by each individual turbine cumulates, leaving a pronounced wake in the downstream region, the so-called cluster wakes.