Selan and Lauren, of Highland Park School, asks :-
How long does it take a raindrop to reach the ground?
Gavin Fisher, a meteorological physicist with the National Institute of Water and Atmosphere, responded.
About ten minutes for most types of raindrops.
Raindrops come in all sizes from about half a millimetre to about 3 mm in diameter. We more or less know this because just how wet you get out in the rain depends on the size of the drops. That is why you can get completely soaked in just a couple of minutes in a thunderstorm (large drops) but you can walk about in drizzle (small drops) for a long time before getting wet. Any water droplet smaller in diameter than half a millimetre isn't a rain drop but is just part of mist or clouds. Any water drop bigger than 3mm will blow out on falling, thus creating several smaller drops.
The smaller raindrops fall at about 5 km/hr (a fast walking speed). A 1mm drop will fall at about 15 km/hr (a biking speed) and a 3mm drop will fall at about 30 km/hr (a very fast biking speed).
As well as depending on how fast the drops fall, the time of fall depends on how high they start from. Low clouds, which can produce light winter rain, will be about half to one kilometre high. Medium level clouds, which often produce heavier rain, will be about two to five kilometres up. Big thunderstorm clouds, which can produce the largest drops, can be up to seven to ten kilometres high.
So the smaller drops fall slower than big drops but dont have as far to fall. Using these figures you can work out that all raindrops take much the same time to fall, about ten minutes.