Raindrops Keep Falling On My Head

This past Monday, another heavy rain event struck the area.  Particularly hard hit were residents in southwestern Richland County and neighboring areas in northeastern South Dakota.

Some locations received around 2 inches of rain in less than 30 minutes with reports of raindrops describe as large as quarters by some residents.  But can a raindrop actually become that large?  The answer simply is no.  In fact, raindrops larger than 8 millimeters (mm) are extremely rare and most raindrops are only around 1 mm in diameter (there are about 25 mm in one inch).

That same day a brief shower passed over Fargo Moorhead with very large drops which were likely similar to what fell in the heavy rain event to our south which makes me believe that the raindrops where likely in the 5 to 8 mm diameter range.  When you are use to seeing 1 mm raindrops, it is easy to see how something multiple times larger than average will give the illusion of the raindrops being larger than they really were.

2 Responses

  1. A meteorologist down here in Florida told me that the technical definition of a drizzle isn’t what we usually think of a drizzle being, with is more often a rain. So, 8 mm … Is it okay to round up to a centimeter?

  2. Go ahead and round up. 😉 although, that size is extremely rare. Most “big” drops are around 5-6 mm. There have been some 1 cm raindrops measured. That must have been quite the sight!

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