An anemometer that utilizes the principle that the convection of heat from a body is a function of its ventilation. In its usual form it consists of a thin platinum wire heated to approximately 1000°C so that its temperature is relatively independent of ambient temperature variation. Wind speed is determined by measuring either the current required to maintain the hot wire at a constant temperature or the resistance variation of the hot wire while a constant current through the wire is maintained. Wind speeds as low as a few centimeters per second can be measured in this manner. The response time constant of the wire can be made very small. See hot-film anemometer.