The film follows Wesley, a trainee at the Weather Bureau of Investigation (WBI), as he learns about precipitation. Through a series of engaging lessons, he discovers the different forms of precipitation, such as rain, snow, and dew, and how they relate to temperature changes and water vapor in the air. Wesley's journey includes practical observations and experiments that help him understand how clouds form and the processes leading to precipitation. Ultimately, he learns that precipitation occurs when water droplets or ice crystals in clouds become too heavy to float and fall to the ground.