ABSTRACT

The vane anemometers usually employed in meteorology are not used in caves because the slow air speed (often less than 0.1 m s−1) is outside their range. Hot wire anemometers are more suitable but they detect only the velocity and not the direction of the airflow that, in caves, may have two ways (in or out, with reference to a given environment). The direction may be identified by using two probes, one of which is shielded. By swapping the position of the shields, it is possible to determine the direction of air flow since the probe that is shielded from the prevailing air flow will record a lower air velocity.