A convector for air cooling of a fluid flowing in a pipe, comprising: - a path for a cooling air flow comprising an inlet from and an outlet towards the environment, - a heat exchange section comprising at Ieast one tube bundle defining a heat exchange surface, said section being provided in said path for the air flow, - fan means producing said air flow along said path, so that said air flow externally invests said tube bundle on said; heat exchange surface, - a humidifying section arranged in said path, upstream of said heat exchange section, where water is atomized to be invested by the air flow, characterized by comprising a wetting device for wetting directly with water a portion of the heat exchange surface of said tube bundle to further cool said portion of tube bundle.