Hello and welcome to this month's edition of Spotlight on Natural Resources. Here with me today is Duane Friend, and Duane is an Illinois Master Naturalist Coordinator and Climate Specialist with the University of Illinois Extension. How are you doing there today, Duane?
Duane Friend: 00:27I'm doing fine, Gavin. It's been a while since we've talked, so glad to be back.
Gavin Flure: 00:31It has been, and we have a riveting topic here, or I should say a cold topic to talk about today. And that is what is the difference between snow, sleet, and freezing rain?
Duane Friend: 00:46Well, that is a really good question. That is a question that I get fairly often, so we'll just get right into it and and talk about the differences between the the three of them. So snow, we're all familiar with snow. We know it's this white puffy, fluffy material that comes down. But just to talk a little bit about how it forms, one of the things to know about snow is that when it forms, it's taking that gas form of water, or we call it water vapor, and instead of going through to liquid water, it goes directly from a gas to that solid in terms of the crystallization of that water vapor. So snow is something that goes directly from a gas to solid. Doesn't have that liquid phase in between there.
Duane Friend: 01:39A little bit of trivia on snow, so I don't know how often there are still trivia contests out there. But as far as snow in terms of precipitation, doesn't really matter what time of year we're talking about. In the middle latitudes, all precipitation starts out as snow. It usually has to fall through about 1,000 feet above freezing temperatures to melt, which in the spring, summer, fall here in the Midwest, it can do that pretty easily. But winter is the only time of year when that snow can stay together as snow and make it all the way to the ground.
Duane Friend: 02:16But in terms of how it forms, one of the things that has to be in place for that formation to start is you've got to have little particles in the air, things like dust, smoke, pollen, or something like that, for those little microscopic water molecules to start condensing onto and changing from that water vapor to that crystalline form of snow. And when it first forms, again, it's really small. It's microscopic in size. But as it continues to gather more and more water molecules on there and changing from that gas to that crystal, that crystal begins to grow. And depending on the temperature of the air, depending on the humidity, the way that crystal forms can form in millions and millions and millions of different ways. And it can start out with kind of a faucet or a prism, and then it builds with faucets. It can also have branching. You can have combinations of those. So you may have heard that no two snowflakes are alike, and that could very well be true. Although I always think that over the course of Earth's history, out of the trillions and quadrillions of snowflakes out there, there's probably been a couple that have been pretty close. But again, that's just me, my opinion.
Gavin Flure: 03:41Yeah. I I completely agree with you there. And so sorry to interrupt you there. When snow forms, is that and you were talking about the humidity, is that also a factor in us getting larger air quote snowflakes there as opposed to smaller ones?
Duane Friend: 03:59That's another really good question. Yeah. If you think about when you usually see the larger snowflakes, we usually see those when the temperature is hovering right around 32 degrees or maybe even just a few degrees above that. So what happens in that case is you have those snowflakes and they're, I guess, what you would call normal size falling. But as it gets close to the ground, the outside edges of those snowflakes have a little bit of melting to them. So you get a little bit of liquid water on that snowflake. But then when another snowflake collides with it, the two will attach. And then you'll have that happen multiple times. So that is what creates those really large snowflakes. And that's usually when we have it occurring is when those temperatures are near freezing.
Duane Friend: 04:44When the air is colder, the air can't hold as much water vapor in the air. So it can still snow. It's never too cold to snow. It's just that those snowflakes are going to be much, much smaller. When you start getting down, say, fifteen, twenty degrees, those snowflakes are really tiny. But you can still have them. And you can still have snow even when it's below zero. Because since the air can't hold much water vapor to begin with, anytime you've got any water vapor at all in the air in those really cold temperatures, it's close to 100% relative humidity. So that opportunity for precipitation can take place.
Gavin Flure: 05:25Yeah. Well, makes much more sense in terms of the larger snowflakes versus the smaller snowflakes. So that makes a complete sense. But, yeah, when you started off, I'm like, alright. Let's go back to some grade school science class here, that I'm remembering some of these pieces from. But yeah. But since sleet and freezing rain are both frozen water, why are they different than snow?
Duane Friend: 05:50Okay. Well, let's let's go ahead and go with sleet first. And sleet is something that if we we've ever experienced it, we usually don't experience it for a long period of time. It's typically something where we're transitioning from rain and then maybe have a short period of sleet and then it goes on to snow, or maybe the opposite. And that's usually because we've got another air mass that's coming into the area, whether it's a cold air mass or a warm air mass.
Duane Friend: 06:18But let's say we're transitioning from rain over to a colder air mass. What'll happen, and this is what happens in either case, is you've got a layer of warm air not right at the ground, but say several hundred or maybe a thousand feet up or even more in some cases. So as that snow forms and it's falling down to the ground, it'll go through that warmer air that's above freezing, it will melt, and it'll become rain. But then it goes through a colder layer of air close to the ground. And when that air is thick enough that those water droplets can freeze, so in this case, it's changing from liquid water over to ice pellets, that's when we get sleet. So that sleet is forming when you've got a warm layer in there that is far enough off the ground that that snow can melt, become rain, but then it refreezes before it hits the ground.
Duane Friend: 07:19Freezing rain has the same occurrence, but in this case that warm air layer is much closer to the ground. So you start out with snow just like we did before, gets down to that warm air layer, it melts, becomes rain, but then that cold air that's right at the ground level isn't very thick. And so that rain doesn't have an opportunity to freeze before it hits the ground. But then when it does hit the ground or hits houses or hits trees or cars or whatever, it freezes at that point. So that's when we get freezing rain. So it's really just a matter of where that warm air layer is above the ground, whether it's far enough up that that rain can melt before it hits, or if it's closer to the ground, doesn't allow that rain to freeze before it hits the ground.
Gavin Flure: 08:10Interesting. I appreciate that information there. That's yeah, that's that's really interesting, all all depending upon where the layers are. Very cool. So which one of these is the most dangerous?
Duane Friend: 08:27Well, if we look at snow, we know that we can have lots of snowfall in some cases. And I think the record for Illinois, it's a very old record, I think in 1900 in Astoria for a twenty four hour snow event, there was like 30, around 37 inches of snowfall. And these days, we typically don't get a lot of heavy snow events anymore, but we know that there can be hazards associated with that heavy snow in terms of driving, in terms of it being slippery roads, in terms of health issues, you know, somebody is out shoveling snow. With sleet, because it's typically a short time occurrence, we don't have a lot of issues with that.
Duane Friend: 09:13But out of all the three, I would say freezing rain is by far the most hazardous. Freezing rain events can last for multiple hours and in some cases several days, So you get that freezing ice over everything, makes it in a lot of cases impossible to drive. If people try to walk outside, they very easily can slip and fall. And you also have hazards with things like electrical lines falling down, trees falling down. So really, the freezing rain is probably the most hazardous out of the three in my opinion.
Gavin Flure: 09:50Yeah. No one, nobody likes the ice and too dangerous out there for a lot of people. And people shouldn't try to drive during those conditions. It would be my opinion on
Duane Friend: 10:01Yes, that's true. Probably one of the first, or I should say not the first, but the worst ice event that I've been through. And I know probably a lot of the listeners, including you, would not have experienced this. But there was an ice event in the spring of nineteen seventy eight. It was right around Easter weekend. It lasted for about twenty four to thirty six hours over most of central southern Illinois and then adjoining states. And it had major power outages over that entire area. There were some places that didn't get their power back on for almost two weeks because there were so many lines that were down. So that one was just a very devastating event, which happened in March of nineteen seventy eight.
Gavin Flure: 10:52Wow. Yeah. I do remember one as a kid where we were we were without power for about three days ourselves. So that was the worst one that I've seen anyway. But yeah, that that does not. Man, feel sorry for some of those folks out there, especially if they didn't have any, any additional heat sources.
Duane Friend: 11:14Yeah. That's true. And that's one of the things that we don't really think about in terms of, you know, disaster preparedness. We don't think of that happening very often, but it happens really a lot more often than people think.
Gavin Flure: 11:27Yeah. So what are the trends in the occurrence of each of these types of precipitation?
Duane Friend: 11:37Okay. So as far as what the trends are for winter weather in general and winter precipitation, one of the things that we are seeing not only in Illinois but throughout the Midwest is that our winters are trending warmer. So as time goes on, we're getting less and less of the frozen precipitation events or the snow events, getting more of the rain events and just talking about at the time that we're doing this podcast, they're talking about, and this is in early December when we're doing this, we're talking about some heavy rain occurring in the next couple of days where thirty years ago we probably would have been talking about snow warnings going in. But because we're getting warmer, we're getting less snow, we're getting more rain, but then we also have the potential for getting more of the freezing rain events because we can still have those temperatures close to freezing in a lot of cases. So I think we have to really be thinking about and being prepared for more of those freezing rain events because we do have the potential for more of those occurring. I'm not saying that that's inevitable, but we do have to just look at what the trends are. And while we would like most of that to be rain and not freezing rain, we still have to be prepared at least in terms of what we have in terms of having things at home in case we would have to stay home for a day or more because of those freezing rain events and the hazard that they may present.
Gavin Flure: 13:19So in terms of preparedness, they're on potentially making, you know, your area safe for yourself and your family, I'm thinking in terms of like, you know, snow melt or something like that. Are those going to be the best options for folks out there? Or is there something else that they should have on hand?
Duane Friend: 13:42Well, with freezing rain, sometimes it's really hard. It's almost impossible to really speed up the melting for that because if you've got a large driveway, for example, I don't think people are going to go out and spend a huge amount of money to try to clear off those areas, maybe for sidewalks. The only thing with salt related products is that it is going to tear up the concrete. It's going to wear the concrete out much quicker than it would otherwise. So people have to be very diligent when they're using that snow melt.
Duane Friend: 14:15But in other cases where we're talking about having to stay home, maybe being holed up in the house for a couple of days, just like any other type of disaster preparedness, you need to make sure that you've got plenty of food on hand, plenty of water. There are maybe opportunities or not opportunities, but instances when the power goes out. So you've got to be prepared for potentially colder temperatures in the house if you don't have heat in the house. You want to make sure you've got other necessities like medical supplies on hand, especially you want to make sure you have all medicines in plentiful supply, especially during the winter. So it's kind of those general things that you need to think about that would be related to any type of potential hazard where you would have to stay home for multiple days. And I think here in the last couple of years, I think a lot of people have learned what it takes to stay home for some time. So those things play into account just as much now as they did a couple of years ago when we were going through COVID at home.
Gavin Flure: 15:29Yeah. I could not agree with you more on that. Definitely need to have something around to keep yourself busy during those times.
Duane Friend: 15:36Yeah. I can still remember right when things were beginning to shut down, and I was at the grocery store. And somebody the two things that they were getting were wine and toilet paper. So, to each his own, they have their own necessities.
Gavin Flure: 15:51Exactly. Yes, yes, everyone does. So, Duane, thank you so much for all of this wonderful information on snow, sleet, and freezing rain. Do you have any additional resources to share at this time?
Duane Friend: 16:07Yeah, if somebody would like to know a little bit more about winter precipitation, I did do a webinar on that subject last year, and we have a YouTube recording of that. So if somebody went in and just did a general search for Illinois Extension winter precipitation, it should bring up that YouTube video. So and it's about fifty to fifty five minutes long, so you can watch that at your leisure.
Gavin Flure: 16:36Perfect. Thank you, Duane, for joining us today, and I appreciate your time.
Duane Friend: 16:40Well, thank you. Glad to be on.
Gavin Flure: 16:44And that concludes this month's edition of Spotlight on Natural Resources. Thank you for listening. Have a wonderful day.