Hey Ray! Why Does Snow Sparkle?

PITTSBURGH (KDKA) -- Have you ever noticed on very cold mornings in the winter, the snow will have a sparkle to it?

It is actually not the snow that twinkles. There is something else that happens.

While snow is comprised of ice crystals, it takes something a little different to make the surface of the snow look like someone dumped glitter on it. It is because of something called "Hoar Frost."

While it has a weird name, what creates hoar frost is a neat process.

Hoar frost forms when water vapor changes to a solid, or ice, while skipping the liquid phase. We call this deposition. That water vapor encounters the frozen snow, causing it to freeze, leaving ice crystals behind. Those ice crystals sparkle, making the snow twinkle.

You may notice that sparkling snow is usually seen in the morning or at night. This is an important part of the process.

At night, the air over the snow on the ground cools the surface snow more than the snow inside. This causes an evaporation process to take place, releasing some water vapor into the air. This process is the opposite of deposition. It is called sublimation. This is where ice, or a solid, turns directly into a gas, while skipping the liquid phase.

Have you ever seen shrunken ice cubes in the freezer? That is sublimation. The ice cubes are just evaporating, like some of the snow.

The snow that evaporates is the source of the water vapor that freezes on top of the snow, creating the ice crystals.

Hoar frost doesn't just occur on top of snow, though.

You can see it collect on any cold surfaces. Aside from sparkling snow, around here we see it happen most frequently on lake surfaces. Hoar frost creates little frost balls, like you see here from Deep Creek Lake!