Diamond Dust?

If you happened to be out and about in Sioux Falls today, you might have noticed some glittering objects in the sky. You probably thought it was snow - which was right - and probably thought that snow was just blowing around. The only problem: light winds. What was actually happening was a phenomena when snow forms without clouds. I'll go a little in depth with this, but you can always ask questions if you have any.

So... for ice to form you need something for it to form on, or it has to be REALLY cold. You can potentially have below-freezing water that stays as a liquid, and then touch it and it instantly turns to ice. This "thing" the water freezes on is called "ice condensation nuclei" and can be anything from pollutants from humans to just dust in the air. We'll pretend that this "diamond dust" was from dust and not humans for now...

So we know how ice crystals form, why didn't clouds for first? The answer to that is you need what's called an "inversion," or a region of air where temperatures *increase* with height, where you would typically notice temperatures falling as you go higher above the earth. An inversion then traps in those pollutants (the dust we mentioned above) near the surface. In this case we were chilly, in the teens, so that means the air above us would be somewhere close to that or even potentially slightly warmer. As you might know, hot air rises - so when warmer air hits air that is even warmer than itself, it stops rising. That point is where an "inversion" occurs and traps in all the air below it.

So, we had lingering humidity, trapped air, and trapped dust particles in the ideal growth temperature for snow (about 10 or so degrees Fahrenheit) - all of that equals this picture below:

Unfortunately my digital camera was not working due to dead batteries, so I found this picture from Japan above. Hopefully you saw it for yourself, and if you are interested in reading more about why this happened and why this occurrence was actually a rare instance given our temperatures, check it out in Wikipedia!

Have a great night and enjoy the slight warm-up for Wednesday!

~KDLT Meteorologist Aaron Shaffer