Seeing how much temperatures have dropped lately, it might be fun to learn about an interesting winter phenomenon- frost. This may come as a surprise, but there are actually many different types of frost. Frost is basically water vapor that becomes solid. It forms when an outside surface cools past its dew point (the point when the air is cold enough to turn the water vapor in the atmosphere into liquid); this liquid frozen over is what we call frost.
One type of frost is air frost, which is when temperatures drop to 0 degrees Celsius or below.
Ground frost is when ice forms on surfaces whose temperatures drop below water’s freezing point, like the ground, objects, or trees. This can sometimes happen without air frost because the ground can get colder faster than the air. You might also hear it be called grass frost, when only the grass freezes over despite other surfaces being fine.
Hoar frost, also known as radiation frost, is particularly breathtaking. When the surface temperature is below freezing, beautiful droplets of ice crystals form in the place of water droplets. You can find hoar frost on exposed plants near unfrozen water, the ground, or even the most delicate objects like wires, leaves, or spiderwebs. You may have even noticed these little crystals in your fridge or freezer.
Rime almost looks like solid ice, and is formed very quickly in very cold, wet climates. It also forms in windy weather- rime develops when extremely cooled water droplets in the fog freeze upon being exposed to the wind.
Advection frost is made up of small spikes of ice. It forms similarly to rime frost; it is created when a cold wind blows over a surface.
Glaze, a smooth, clear ice, is another form of frost similar to rime. It is when supercooled rain touches the ground and freezes, also known as freezing rain. Even liquids that aren’t supercooled can produce glaze if the ground is below freezing. Glaze is extremely dangerous because of how invisible it can be to people, especially drivers. Its weight also can cause power lines or tree branches to crash.
Window frost forms when a glass window is exposed to both cold air from outside and moist air from indoors. It is created by the conflicting warmth and cold. Window frost can be seen pretty often in cold places, but it was especially noticeable before the invention of double-paned windows.
Lastly, there’s a special frost flower. It is extremely rare and hard to find since it occurs only in certain conditions. For it to form, the temperature must be just below freezing while the soil is unfrozen yet moist. Water pulled up from the soil then has to freeze in the stem of a plant, and then eventually expand and split the stem. This process needs to happen multiple times, until it forms the fragile layers of ice that make up a frost flower.