Abstract: An electical current flow sensor, where a spherical surface thereof is subjected to an in-flowing fluid in order to the speed of the fluid. The spherical surface is formed by a body made of a good thermally conductive material. An electrical resistor is disposed in a cavity in the interior of the body of good thermally conductive material. The electrical resistor is placed in a good heat exchange with the wall of the cavity. The electrical resistor is adjusted to a preset temperature by electrical current feed, whereby increased fed-in electrical current is measured and serves as a measure for the current flow speed.