This morning it was raining so hard the drops were painful. What causes this? Is it drop size and the height from which they fall? Or is there another mechanism that increases the speed at which drops fall? The rain seemed to be coming down especially hard, and drops hitting the ground bounced high into the air.
• Two things affect the energy of a raindrop and hence how painful it feels when it hits your head: its size, and the speed at which it falls. In practice, raindrops cannot grow bigger than about 5 millimetres in diameter, as air…
