Diamond Dust: Snow From The Clear Blue Sky?
Can it really snow from a cloudless sky? Learn about the meteorological phenomenon known as diamond dust and how and where it forms.
Quick Reference
- What: Tiny ice crystals that form near the ground and reflect sunlight, sparkling like diamonds.
- Sky: Often falls from a cloudless blue sky. Also known as “clear-sky precipitation.”
- Trigger: Temperature inversion, where warmer moist air sits above near-surface air well below zero.
- Cold required: Negative double-digits. Most common at -20 F, -30 F, or colder.
- Where: Antarctica, the Arctic, and rarely the northern tier of the U.S. and Canada.
Can it really snow on a cloudless, sunny day? It can if it is diamond dust. More like Mother Nature’s tinsel than snow, this meteorological phenomenon is caused by millions of tiny ice crystals that form near the ground. As they float slowly in the air (much like household dust) they reflect the sunlight, which makes them sparkle like diamonds.
What Causes Diamond Dust Snow?
Diamond dust is not your typical snowfall. Unlike ordinary snow, it can fall from a cloudless sky, which is why it is sometimes known as “clear sky precipitation.” This is possible thanks to another weather phenomenon called temperature inversion.
Normally, air temperatures get colder as you travel from ground level up to higher altitudes, but with inversion, this is flipped. Cold air sits near the surface with warmer air above it. This weather setup makes it possible for diamond dust to form because the warmer air contains more water vapor. As this warmer, moister air mixes with the colder air below it, its water vapor is carried into the cold air. Then ice crystals may form (without the need of moisture from clouds overhead).
It’s Got To Be C-O-L-D!
Of course, the near-ground air temperatures must be cold enough too. And we are not just talking temperatures around the 32 degrees F freezing mark. In order for water vapor to condense directly into ice crystals (which is what happens when diamond dust forms) you need temperatures MUCH colder than 32. This weather phenomenon typically only forms when air temperatures drop into the negative digits: -10s, -20s, -30s, and -40s.
Where Can You See Diamond Dust?
If you have never seen diamond dust before, it is because very few places, other than Antarctica and the Arctic, get that cold. Occasionally, portions of Canada and the northernmost tier of the United States (locations in Maine, Minnesota, Wisconsin, and Wyoming) can see temperatures cold enough to create this sparkly snow.
Fun Fact: At the Antarctic Plateau, diamond dust can be observed 316 days a year.
Although it does not fall from clouds, it is a kind of precipitation, just like snow or rain. (Any form of water that falls from the sky earns the title of precipitation.)
Like ordinary snow showers, diamond dust can continue for several days without stopping. But no matter how long it falls, it likely will not accumulate.
Diamond Dust Hot-Spots
| Location | Days per year |
|---|---|
| South Pole, Antarctica | 316 days |
| Eureka, Nunavut | ~50 days |
| Fairbanks, Alaska | ~30 days in cold winters |
| International Falls, Minnesota | A few days per year |
| Yellowknife, NWT | 10 to 20 days |
The National Weather Service tracks every measurable precipitation type at every U.S. station, including ice-crystal observations from northern Alaska and the Upper Midwest.
Wondering how cold winter will be in your neck of the woods? Check out our “teeth-chattering” cold forecast.
Frequently Asked Questions
What is diamond dust?
A ground-level cloud of tiny ice crystals that reflect sunlight and sparkle like glitter. It often falls from a cloudless blue sky.
How does diamond dust form?
A temperature inversion sets up. Warmer moist air sits above bitterly cold surface air. Water vapor mixing down into the cold layer condenses directly into ice crystals.
How cold does it have to be?
Well below zero. Most diamond dust forms when surface temperatures are -10 F, -20 F, -30 F, or colder.
Where can I see diamond dust?
Antarctica and the Arctic see it most. The Antarctic Plateau gets it 316 days a year. Northern Alaska, Nunavut, and the coldest stretches of Maine, Minnesota, Wisconsin, and Wyoming see it occasionally.
Is diamond dust the same as snow?
It is a form of frozen precipitation, but the crystals form near the ground rather than falling from a cloud. They almost never accumulate, even after days of “snowfall.”
Does it accumulate?
Almost never. The crystals are far too sparse and too small. Diamond dust can fall for days without leaving more than a faint glitter on flat surfaces.
Why does it sparkle?
The hexagonal ice crystals act like tiny mirrors. When direct sunlight hits them, each crystal flashes a single point of reflected light, producing the gemstone-like effect that gave the phenomenon its name.
Tell Us
Seen diamond dust in person? Tell us in the comments. For more rare-precipitation reads, see our types of rainbows and aurora borealis entries.
Tiffany Means
Tiffany Means is a freelance writer and a degreed meteorologist. She specializes in weather forecasting and enjoys making the subject of weather (and the science behind it) more relatable. She currently resides in the Blue Ridge Mountains of North Carolina.
- Tiffany Means
- Tiffany Means
- Tiffany Means
- Tiffany Means
WOW! This may be the same thing I saw on cold mornings in eastern Idaho! Didn’t have cell phones with cameras.
Thank you!!