Frozen Wonders
Winter Weather Phenomena
(Snow, Ice, Frost, etc.) of North Carolina

January in North Carolina is a wonderful time to explore the outdoors. Unlike a typical adventure, where you head for a particular destination, in January you're seeking a natural phenomenon. Accordingly, you can just as often have the adventure in your backyard, as you can at some remote location. However, certain locations are better than others. The trick is to learn a little bit about the phenomena before you head out, so you know exactly where to look, and what you're looking at when you find it.

North Carolina is a great state for observing and photographing frozen precipitation, but you might wonder why this is so. The reason is simple. As any realtor would tell you, it's location, location, location. With the Atlantic Ocean on one end and the Appalachian Mountains on the other, North Carolina contains four distinct physiographic zones—barrier islands, coastal plain, piedmont, and mountains—each providing unique weather occurrences. Additionally, the state's latitude allows it to experience a wide range of temperatures. Go a little farther south and frozen precipitation is rare at any time of year. In the far north, everything freezes up in the fall and remains that way through winter, without experiencing the constantly changing weather that we have here.

Okay, you all bundled up and ready to go outside? Grab a magnifying glass if you have one and a camera if you like to take pictures. Now, let's go see what's out there.

Rime Ice

If not the most spectacular form of winter precipitation, rime ice is certainly among the most peculiar. It forms when supercooled cloud droplets (below the freezing point, but still in a liquid state) come into contact with an object, where they then freeze on impact. An interesting thing about rime is that the feathery formations grow into the wind, and continue to do so as long as conditions remain favorable. I've seen rime feathers over three feet long in the higher elevations of the state.

Rime ice is often called hoarfrost, of which it is a variety, but hoarfrost crystals grow slowly on calm nights from a process called deposition, in which moist air that reaches the dew point condenses as ice onto an object that is below freezing. The water vapor in the air converts directly from a gas to a solid (in this case ice) without ever passing through a liquid stage. Rime, on the other hand, forms quickly from supercooled water droplets either falling onto a surface, forced upon a surface by wind, or in unusual cases, such as from the fog generated by hot springs coming into contact with trees. Rime crystals continually build upon one another, creating spectacular structures. Like other forms of frost, rime can form on clear nights as long as there is sufficient moisture in the wind-driven air.

The typical conditions required for rime ice to form occur generally only in the mountain areas of the state, usually near ridges. Particularly good places to see it are on Roan Mountain, Grandfather Mountain, Mount Mitchell, the Blue Ridge Parkway from Asheville to the Smokies, and Cherohala Scenic Skyway near Robbinsville. As long as the roads are clear, you can drive to high elevations at all of these places.

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Sunshine on rime ice causes it to melt and fall off quickly, even when the air temperature is very cold, so on clear days you don't want to wait too long to head out, especially if you plan to take photos. The best time to see it is right after sunrise, before the sun's rays become intense.

Icicles

The quintessential form of frozen water, icicles delight children and adults alike. I've learned to drive slowly by certain north-facing roadcuts in the mountains. Invariably, there will be someone standing in the middle of the road taking pictures of the icicles growing on the exposed rock. As we learned in grade school, icicles form from dripping water that is exposed to freezing temperatures, and since the water continues to flow from its source, the ice buildup continues.

There are three kinds of icicles. One type forms from the top down, like stalactites in a cave, and the other type forms from the bottom up, like stalagmites. Sometimes the two converge, forming an ice pillar. The most dramatic formations of these three phenomena occur at small, overhanging waterfalls. The base of the waterfall begins to freeze into rounded glomeruls, and if the temperature remains below freezing for a long period, the formation takes the shape of a volcano, with the waterfall falling into its center. Meanwhile, icicles grow from the top down along the edges of the main water flow, and eventually these stalactites merge with the cone-shaped stalagmite below. If it remains cold enough, the entire width of the water flow will freeze from the outside in, leaving the flow of water constricted within the ice pillar. This same effect also occurs on sloping waterfalls that don't free-fall, but the water freezes as sheets instead of icicles.

Icicles occur across North Carolina wherever there is dripping water and freezing temperatures. In the central and eastern portions of the state, icicle formation is mostly limited to roof overhangs after a snowfall. Most icicles grow in the mountains, where there are numerous manmade and natural conditions for their formation, such as roadcuts, exposed rock cliffs, and waterfalls. The most common condition is a north-facing roadcut. South-facing cuts are normally dry, but those facing north often have small seeps that drip throughout the winter.

Roads in the North Carolina mountains where you can see great icicle displays include NC 215 from a half mile south to two miles north of where it goes under the Blue Ridge Parkway at Beech Gap, Cherohala Scenic Skyway near Robbinsville, and numerous places along the Blue Ridge Parkway. Some of the best waterfalls for ice formation include Moore Cove and Looking Glass Falls near Brevard, Douglas Falls near Barnardsville, Bridal Veil and Dry Falls near Highlands, and Silver Run Falls near Cashiers.

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Snow

As any old-timer can tell you, snow can fall anywhere in North Carolina, but as any child will tell you, it doesn't fall often enough. Obviously, snow occurs most frequently in the mountains, but the Piedmont usually receives at least a couple of decent snowfalls every winter, and it's not unheard of for the coastal areas to get a good snow. This past January a frigid air mass from Canada dumped a foot of snow on the Outer Banks. That's a rarity, though. That 2003 storm was the only coastal snow of significance since Christmas, 1989.

You don't need me to explain what snow is, but at least let me try to convince you to observe it more closely the next time if falls. Hold a black cloth or sheet of construction paper to collect the snowflakes and use a magnifying glass to observe the intricate details of the crystals. If you've never done this before, I should warn you to dress warmly because you'll be at it for a while. Once you see that first closeup view of a lacy, star-shaped snow crystal, you'll feel like a child whose parents finally let you go outside and play in the snow.

While snow is rare in the extreme eastern portion of the state, one type of snowfall occurs only on the coast. You've probably heard the term "lake effect snow" in reference to major storms in the Great Lakes area, but on rare occasions the conditions permit the same effect to happen here. If the temperature drops below freezing during an easterly wind, the air picks up moisture from the warmer ocean and forms clouds. When these clouds reach the colder air situated along the coast, the result is a snowfall along a very narrow band. I've left Nags Head during blizzard conditions and by the time I crossed Alligator River only 20 miles to the west, there wasn't a cloud in the sky. Meteorologists can predict lake effect snows fairly well, so the next time the forecast calls for it, head for the coast and experience this rare and exciting event.

Frost

The most common of all frozen winter phenomena, frost occurs on calm nights from a process called deposition (see the description under rime ice). Like snow, many persons take frost for granted, but not those who observe it closely. There are many types of frost, with each type forming spectacularly beautiful crystals.

You can observe one type of frost without even leaving the house. Window frost forms when the glass cools to below freezing and warm, moist air on the inside of the house condenses as frost on the window. The elegant, feathery crystals of window frost look like exotic ferns. Single-pane windows (like those on most older homes) provide the best surface for window frost to form. The inside surfaces of double-pane windows rarely get cold enough.

Sleet and Freezing Rain

No one needs an introduction to these familiar winter events. Due to the dangerous conditions created by both freezing rain and sleet, it's best to experience these events within walking distance of your home. Sleet (rain that freezes before it reaches the ground) has no redeeming quality that I can see, but a good freezing rain (rain that freezes after it hits an object) encrusts every branch and twig in a coating of ice, creating one of my favorite winter weather events from an observational standpoint.

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The best time to see and photograph freezing rain is well after the storm has passed. If you go out when it's still cloudy, the ice merges nearly imperceptibly with the overcast sky. The day after a freezing rain is often clear, with the blue sky providing the perfect contrast to the ice. Few winter events are as stunning as ice-encrusted trees set against a blue sky.

Frozen Bodies of Water

North Carolina temperatures rarely stay cold long enough to solidly freeze large bodies of water, but it does happen, and with it the opportunity to witness some unique events. In 1994, a cold spell gripped the entire state for more than a week. Some of the coldest temperatures were on the coastal plain, with temperatures on the Outer Banks hovering a few degrees above zero for several days in a row. Incredibly, the upper portion of Currituck Sound froze solid. At Oregon Inlet, only the main channel remained unfrozen; crews at the nearby Coast Guard station had to use boat motors to churn the water and create an ice-free channel from the station to the inlet.

Anytime you have the opportunity to explore a situation like this, jump on it. (The opportunity, NOT the ice!) While small ponds and lakes simply freeze over and leave a rather boring sheet of ice, larger bodies of water that have wind-induced waves (including freshwater lakes) and those affected by tidal forces, allow unique ice formations to occur. The most interesting ice phenomenon I've witnessed happened on Currituck Sound during the cold spell of 1994. Undoubtedly, the sound froze at high tide, but not solidly enough to maintain integrity when the tide retreated. As the tide went out, the ice sheet broke up, leaving a ring of ice around pier and bridge pilings at the high tide mark. Then, at low tide the sound refroze-this time solidly enough to maintain a solid sheet and prevent the next incoming tide from breaking it up. So, what I witnessed was a frozen body of water with an ice ring on every piling about one foot above it. Neat stuff!

Winter weather phenomena is extraordinarily varied and for those who study it, scientifically complex. I've only touched on a few of the basics in this article, but the only thing you really need to know is that if you just go outside and pay attention, you'll see things that you never knew existed, and you'll have a lot of fun doing it.