I am such a geek sometimes. I think this is fascinating; it's by my favorite weather guy on KOMO4's website:
How do snowflakes get so large?
Story Updated: Mar 15, 2009 at 12:03 PM PDT
By Scott Sistek
One of the most remarkable facets from Sunday morning's snow was the unusually large size of the snowflakes. In fact, a reader from Shoreline described it as "it looked like someone was plucking chickens in the sky."
As to why they're so large, it's a factor of both temperature and intensity of the precipitation.
First, let's tie it to rain. You've noticed most of the time around here, the rain is generally light and the raindrops are small enough that you won't get too wet if you're caught outside. But then there are sometimes when the raindrops seem considerably larger and can leave you soaked in seconds.
Large raindrops mean that there are strong updrafts inside the clouds above your head. These upward blowing winds can hold raindrops inside the clouds for a longer period, allowing them to continue to grow in size until they finally become heavy enough for gravity to finally win the battle over the updraft, allowing the raindrop to fall to the ground.
That's why thunderstorms tend to have large raindrops, as they tend to also have strong updrafts. It's also why rain in the Midwest and East Coast can quickly leave you drenched.
Now, it works for snow too, and it helps to have warm temperatures as warmer air can hold more moisture than colder air. So when you've got temperatures on the fringe of freezing, as we did Sunday, *and* a heavy precipitation event, that can lead to big snowflakes. Had it been, say, 40 degrees Sunday it would have been like a tropical downpour.
Last edited by salsabike; 03-15-2009 at 01:41 PM.
"My predominant feeling is one of gratitude. I have loved and been loved;I have been given much and I have given something in return...Above all, I have been a sentient being, a thinking animal, on this beautiful planet, and that in itself has been an enormous privilege and an adventure." O. Sacks