Vaisala Tethersondes are specially designed for atmospheric boundary layer measurements, and accurately measure PTU (pressure, temperature, and humidity) and wind speed / direction. The sensor modules are sealed, consumable components that can be discarded after their usable lifetime and replaced with a fresh module. Wind speed is measured with a patented three-cup anemometer and a light-chopper tachometer. The anemometer is very sensitive and has a very low starting speed. The Tethersonde's aerodynamic wind vanes and a small digital compass are used to measure wind direction.
