<prompt> Asmann psychrometer is useful for -HumidityVelocityTemperatureSound intensity  <response>: A psychrometer is an instrument to measure the humidity of the air. Assmann psychrometer is a poable instrument to give accurate readings of wet and dry bulb temperatures of air. In this instrument, the air is drawn at a speed of 5 meters per second by clockwork fan. Parks Textbook of Preventive and Social Medicine, 25th Edition, Pg 809 