A Momentum Disdrometer for Measuring Raindrop Size from Aircraft *

Abstract

There exists a need to measure raindrop distributions in storms being investigated by radar. A new airborne instrument for such measurements has been developed which measures simultaneously the droplet size and the total liquid water. It is primarily a capillary collector inside of which is mounted a condenser microphone to measure the acoustic wave generated by the transfer of energy from the rain drop to the pickup. This device contains a “built-in” calibration system as it measures both the mass (by measuring momentum) and total volume of identical droplets. There exists a need to measure raindrop distributions in storms being investigated by radar. A new airborne instrument for such measurements has been developed which measures simultaneously the droplet size and the total liquid water. It is primarily a capillary collector inside of which is mounted a condenser microphone to measure the acoustic wave generated by the transfer of energy from the rain drop to the pickup. This device contains a “built-in” calibration system as it measures both the mass (by measuring momentum) and total volume of identical droplets.