Method for operating a wind power installation, wherein the wind power installation has: - an aerodynamic rotor with rotor blades which are adjustable in terms of their blade angle, wherein the rotor is able to be operated at a variable rotor rotational speed, and - a generator which is coupled to the aerodynamic rotor, wherein - the method comprises the steps of: - specifying the air density at the location of the wind power installation, - setting a blade angle (α) of an adjustable rotor blade in a manner dependent on an output power and/or a torque and/or the rotor rotational speed, wherein - the blade angle is set in a manner dependent on at least one pitch characteristic curve (Kα,p), which specifies the blade angle as a function of the output power and/or the torque and/or the rotor rotational speed and in a manner dependent on the air density, characterized in that, - to take account of an air density (ρ) at the location of the wind power installation, the pitch characteristic curve is a pitch characteristic curve (Kα,ρ) which is dependent on the air density at the location and in the case of which the blade angle (α) has, in a manner dependent on the air density at the location, a minimum (α0) in the region of a reference density (ρ0), applicable to the location, of a locational atmosphere, wherein the reference density (ρ0) of the locational atmosphere is a standard density of a standard atmosphere, specifically a reference density (ρ0) with a density (ρ) above or at 1.3 kg/m 3. - an aerodynamic rotor with rotor blades which are adjustable in terms of their blade angle, wherein the rotor is able to be operated at a variable rotor rotational speed, and - a generator which is coupled to the aerodynamic rotor, wherein - the method comprises the steps of: - specifying the air density at the location of the wind power installation, - setting a blade angle (α) of an adjustable rotor blade in a manner dependent on an output power and/or a torque and/or the rotor rotational speed, wherein - the blade angle is set in a manner dependent on at least one pitch characteristic curve (Kα,p), which specifies the blade angle as a function of the output power and/or the torque and/or the rotor rotational speed and in a manner dependent on the air density, - specifying the air density at the location of the wind power installation, - setting a blade angle (α) of an adjustable rotor blade in a manner dependent on an output power and/or a torque and/or the rotor rotational speed, wherein - the blade angle is set in a manner dependent on at least one pitch characteristic curve (Kα,p), which specifies the blade angle as a function of the output power and/or the torque and/or the rotor rotational speed and in a manner dependent on the air density, - to take account of an air density (ρ) at the location of the wind power installation, the pitch characteristic curve is a pitch characteristic curve (Kα,ρ) which is dependent on the air density at the location and in the case of which the blade angle (α) has, in a manner dependent on the air density at the location, a minimum (α0) in the region of a reference density (ρ0), applicable to the location, of a locational atmosphere, wherein the reference density (ρ0) of the locational atmosphere is a standard density of a standard atmosphere, specifically a reference density (ρ0) with a density (ρ) above or at 1.3 kg/m 3.