Small raindrops fall to the ground slowly, while large raindrops fall quickly.
For example, a very small raindrop with a diameter of 0.02 mm, or 1/50th of 1 mm (such a small raindrop is really a mist rather than rain) falls only 1 to 2 cm per second. Raindrops with a diameter of 0.15 mm fall at a speed of about 50 cm per second.
Rain with a diameter larger than 0.5 mm is generally referred to as rain, and rain with a diameter as small as 0.5 mm falls at a speed of 2.2 m/s. Rain with a diameter as small as 1 mm falls at a speed of 6.2 mm/s. Rain with a diameter as large as 3 mm falls at a speed of 7-8 m/s. Rain with a diameter as large as 3 mm falls at a speed of 7-8 m/s. A rainfall of 7 to 8 meters per second is equivalent to a speed of 25 to 30 kilometers per hour. Rain falls at an unexpectedly high speed when it is heavy.