Hi students. I thought I would make you a quick video kind of going over some important points about precipitation and cyclonic weather systems. These are just things I was thinking of this morning when looking at the schedule for the week ahead and thought I would share them with you. Let's see... Oh, I don't want to do that. Alright. So the first thing I want to point out is the beginning of the lesson, we talk about the phase changes of water. And many of you are probably going to be wondering why we're talking about melting and boiling and things like that. We're basically just setting up a foundation because there's a few important points in here. And one of the most, I placed in bold on this slide, which is: heat is released as the latent heat of condensation when water vapor condenses. And why is it so important? It's because it drives a lot of the weather. We seen a lot of the weather system. So that's a very important statement. Second thing I wanted to point out is that we have this discussion on maximum and relative humidity and how much water vapor can be held in the air. And this is going to be difficult for some people because there's a little bit of math involved. There's also, it can be a scientific concept in a social science course. So that may present a challenge. So what I would suggest, and I know I've said this a lot, is to draw some circles in symbols. However, you can imagine this concept. So one thing I put on this slide is think of the cloud as a bag. You can hold a certain amount of something at a given size bag. So maybe a small purse versus a large purse. However you want to think of that, or you can think of something else. If you increase the size of the bag. So we're thinking about warm air, you increase its ability to hold water or whatever you're holding in the bag. A smaller bag will be more full, right? So it'll feel very full, but it's actually holding less. So try to come up with something that helps you easily think about this concept so that it doesn't occupy too much of your time trying to figure out what it all means and the math of it all. So the next thing I want to point out, which is something that often trips students up, is that at the dew-point temperature, and sometimes if you're prone to using the weather app on your phone, you may think about the dew-point it's going to rain. That's not technically what happens. It's significant because it can rain. The dew-point temperature, air cooling to the dew-point temperature, given the conditions of atmospheric moisture and the amount of moisture in the air, rain can occur. But, it's actually the temperature at which condensation occurs. So we're starting to relate back to that first concept, or on the first page. So at this temperature, water vapor condenses so close from gas to liquid, right? Releases heat. We don't need to know that yet. But it's when clouds can form, fog can form, and precipitation may occur. So it's not, we hit the dewpoint, rain happens. Okay, one more mathy type concept. But we're starting to put some of these ideas together. Is adiabatic heating and cooling. So what happens to air as it rises and sinks, right? So how we're putting these concepts together is as air rises from the surface, and do remember air is actually warmed at the surface. So as it rises, it cools, right? Our bag is shrinking. So we have condensation. And what happens when condensation happens? We release heat, right? So it starts cooling at a lower temperature because some heat is being released in that process. Alright. So what do we need to know about precipitation producing processes? Well, we need condensation to occur, we need gas to change liquid water. So we need air to rise and cool, right? So what makes it rise? So we have convection and mountain ranges in France, the collision of air masses. So that's what we're thinking about on this page. What- what's making that air rise? Next up we talk about air masses. Again, this is a fitting picture for the week. I actually work remotely from Texas. I did live in Michigan, which was a state way more equipped to handle that cold arctic air. Texas, as we found out, was not equipped when- when faced with cold arctic air. But anyway, there's this meeting of this warm, moist tropical air from the Gulf, right? See that arrow coming up in the United States? And that colder, drier air from the north over land in Canada. And we're going to start talking about what happens when that warm, moist air meets that cool, dry air. And I- I hope that you even just looking at this kind of can start to see the big picture. Here we go. Okay, this is another thing that I like to draw and maybe that's not working for you. But think about this picture. So imagine down here we have warm air holding lots of moisture, right? We've got a big bag. And so it's got room for a lot of whatever it's holding. In this case, moisture. So as this low pressure spins and it brings in this cold, dry air from the north and it throws that warm, moist air up behind it. What's going to happen is that air is going to cool and it shrinks, the bag shrinks and it's no longer able to hold that moisture. And then we're gonna have condensation, heat's going to be released. Alright, hope you're starting to get this. Now, we move on to a weather process or weather event that occurs because of all that's going on and that is a thunderstorm. You're gonna be given three different stages of thunderstorm. And the best thing to do for this is just to write-down characteristics of each stage. Your updrafts, your downdrafts. What's happening? What's happening at that stage in the storm as far as what we're experiencing? And use the textbook to support that because the textbook is going to give you some characteristics of these stages as well. Okay? And I promised myself I'd keep this to ten slides. So hurricanes is our last, these are tropical cyclones. What's a cyclone? That's a low pressure system, right? So we call them hurricanes. That's what we're commonly- but I- oh, I apologize. I have a bunny that shares my office with me, so it's getting a little loud in here because she's tearing off a cardboard box. So I apologize for that interruption. So hurricanes, right, these are cyclones, these are low pressure systems and they're fed by warm oceans. They're going to form north of the equator or south of the equator, never at the equator. It's just too dull there, just two winds not moving. What's key about that north is that a lot of times students think tropical cyclone, hurricane, warm ocean. It can occur to the north, but what's immediately north of the equator? We're in the tropics right? Either way. But it's north of the equator, so it's north. So when we get our hurricanes, those are forming and following tracks in the North Atlantic. Okay, so what's key here is that the rising air cools and condenses into cloud droplets and rain. And what happens again during condensation, we have heat released, right? Stored, latent heat is released and that's going to drive the storm. So if they're being fueled by warm oceans, they're not forming over land. And what happens over land is they lose that source of fuel. And that's why these- these storms tend to like taper off and peter out as they get over land. Hurricane Katrina. There's a big timeline on the pitch. Don't memorize that timeline. I would never ask you what's going to happen on September first, whatever date. But do know the environmental setting and what made that physical setting, that environmental setting of New Orleans like, so- just so likely to experience a storm of this nature and magnitude. And what- what humans have done in that area to kind of not set themselves up to be faced by that challenge this- so some of the changes that they've made in that physical setting. Okay. That's ten slides and I think that does it. Just if you have any questions, as always, please reach out, meet with your instructor. And of course, take the review quiz, write down those concepts, and be sure to study.