There are countless microbes in the air around us. Microbes such as bacteria and fungi can even be found in the sky's higher altitudes thousands of meters above the ground, floating around as bioaerosols. Dr. Maki Teruya, currently a professor at Kindai University's Graduate School of Science and Engineering, has been studying microbes for many years and contends that these bioaerosols may cause clouds to form and drop rain. The field of meteorology has found that minerals such as dust and ash serve as the ice nucleus of clouds at altitudes above 7,000 meters, but the cause of clouds at lower altitudes has long been a mystery. Can bioaerosols really make it rain? We'll follow Dr. Maki's unique research as he searches among forests and the sky to answer this question.