I can't work out the formula you mentioned before, but the raindrops you mentioned will change their falling form and speed as long as the component, that is, the mass, remains the same during the falling process, as well as the wind direction and speed at different heights. There are also hot air balloons. If the falling speed and direction can be controlled, by the way, if they are not affected by wind and temperature, they will all get the final speed you want. Do you want to know who is fast and who is slow?