A rotor blade for a wind turbine with an aerodynamic device, and an aerodynamic device is provided. The rotor blade includes a main body defining a pressure side and a suction side of the rotor blade, and includes a main body trailing edge section. The rotor blade includes an aerodynamic device with an attachment section for attaching the aerodynamic device to the main body trailing edge section, an aerodynamic section for influencing the aerodynamic properties of the rotor blade, and a buckling section for controlling the orientation and/or the shape of the aerodynamic section with regard to the main body. The aerodynamic device is configured such that it deforms elastically for a force component acting in flapwise direction on the buckling section, and deforms abruptly if a force component of about the size of the stability limit of the buckling section acts in flapwise direction on the buckling section.