In nature, water drops can have a large variety of sizes and shapes. Small droplets with diameters of the order of 5 to 10 µm are present in fog and clouds. This is not sufficiently large for gravity to dominate their behavior. In contrast, raindrops typically have sizes of the order of 1 mm, with observed maximum sizes in nature of around 5 mm in tropical rain showers. Electric fields in the atmosphere lead to the largest sizes. Raindrops in natural rain showers cannot reach arbitrarily large sizes. Which factors govern the maximum size of water drops?