Daily Archives: August 24, 2012

A closer look at the raindrop: Why are there different sizes?

No, this isn’t snow…it’s rain! Heavy, relentless rain

What a beautiful day! Bremerton National Airport recorded a high of 66 today while many other locations hovered on either side of 70 degrees. And yes, it was a chilly one this morning! Temperatures dipped as low as 39 degrees at Sanderson Field in Shelton and it will be another chilly one tonight. This is just one of many signs that fall is coming. Another sign? Increasingly wetter weather.

My sister called me a couple weeks ago from North Carolina and asked me why some raindrops are large and others are small. She noted how after a thunderstorm rolled through their area, the raindrops were impressively large and she had never seen anything like that in Washington. So why the difference and what causes it?

First of all, let’s begin with the cloud. Clouds are made up of water vapor which wraps itself around little particles called condensation nuclei (ie smoke/dust particles). As this process occurs, the little raindrop is born…but it’s sure a lightweight! “Newborn” rain droplets can be as small as 0.0001 centimeters in diameter! At this point these baby drops are too light to fly out on their own. Luckily, the clouds they are raised in are small enough to ensure a little game similar to that of bumper cars, except when a raindrop bumps into another raindrop it grows in size! Interestingly, these raindrops aren’t tear-shaped like most artists portray them to be. In fact, the average raindrop looks more like a hamburger bun!

The “bumper car” process continues until mom can’t take it anymore and kicks the now teenage raindrop out of the house (I think some parents are understanding the process of raindrop development MUCH better now! ;)). In other words, the drop becomes too heavy that it quite literally drops out of the sky and onto our umbrellas.

However, as the teenage water droplet leaves the home it picks up a lot along the way, especially with several updrafts, or sudden gusts of wind that cause the drop to run into other drops. During this process, it continues to grow and grow until finally it hits the ground.

So why doesn’t Washington have huge raindrops? Perhaps as these storms come off of the Pacific they don’t have as much time to build up juicy water droplets that often fall in the country’s midsection. Also, a lot of the rain we get isn’t very heavy or associated with much wind to begin with. So a windy, unstable and moist climate is the best bet for large raindrops!

So there you go, sis! That is one way of explaining the development of a raindrop 🙂

Speaking of those little guys (or big guys in North Carolina’s case!), we’re going to see some this upcoming week! After a beautiful and semi-warm weekend under partly to mostly sunny skies, clouds increase Sunday-Monday and now it appears the rain could fall Tuesday-Wednesday instead of Monday. Models are still flip-flopping, but luckily they’re not like raindrops and grow in size as they do! Otherwise, we’d be in for some pretty massive storms on this side of the mountains 😉

Have an awesome weekend everyone. Enjoy the sun!

Matthew Leach

Forecasting Kitsap

Questions? Comments? E-mail me at: forecastingkitsap@live.com