Ultrasonic humidifiers leverage the piezoelectric effect, where an alternating electrical current drives a transducer, typically a ceramic disc, to oscillate at megahertz frequencies, often between 1 to 3 MHz. This rapid vibration induces intense pressure waves within the water, leading to the formation and subsequent implosion of microscopic vacuum bubbles. The implosion releases localized bursts of energy, overcoming the water's surface tension and resulting in the creation of a fine mist. The size of these water droplets, typically a few micrometers, is inversely proportional to the ultrasonic frequency; higher frequencies yield smaller droplets, creating a finer mist. The energy from the implosion is highly localized and rapidly dissipated by the surrounding water, preventing a significant temperature increase. A small internal fan then propels this cool fine mist into the surrounding environment, thereby increasing the ambient humidity.