TechStuff Classic: Weather Tech, Part 2

This episode originally published on April twenty first, two sixteen. Enjoy. We are now going to join the podcast already in progress. We were able to gather a lot of information once we had those basic tools available to us. But what really pushed meteorology forward is when we could stop relying upon the data that we can gather here on the ground and supplement that with information from the atmosphere itself.

And that brings us to weather balloons. Weather balloons more than just fodder for your roswell conspiracy right right, Swamp gas and weather balloons and weather balloons do more than just act as a subplot in an X Files episode. Right, Yes,

They're very important. Yeah, so they carry instrumentation that collects data about atmospheric conditions and weather balloons have been around for a long time, but more recently they typically carry instruments called radiosond, which is a battery powered device that can measure altitude, atmospheric pressure, temperature, humidity, wind speed. Sometimes there's a GPS element to it, so it can so people on the ground can track where the weather balloon is.

Normally the you tether these devices. You don't just release a weather balloon and say sea, but sometimes you know you need to have that GPS element there too. And getting this information from the atmosphere is really important because it can tell you about how conditions may soon change

on the ground. It's pretty interesting actually to ever if you've ever had a chance to look at some of the data pulled from these, because you see how different conditions in the atmosphere are compared to what we experience here, including some pretty intense winds at higher altitudes. So we've got all this information being collected, and before we get into space, because that'll be the next step outward, I wanted to talk a little bit about what we do

with all that data. One of the things we do is we create databases that have all this information. So that let's say that we have a day with pretty nice weather, we collect all the information about that. What was the atmospheric pressure, what is the temperature, how much humidity was in the air, what was the wind speed, were there any higher low pressure systems nearby? Were the what kind of front had just moved through? All this sort of information, we feed it all into a database.

Collecting that over and over and over again allows us to build a better virtual understanding of how weather works, right, and we can supplement that with more information as we learn more about the weather. Then we would end up using that to help us make some predictions about how weather might be in the future. And to do that, really we use computer models. Typically we would build what

was called a numerical weather prediction model, the NWP. So this is really a model that's made up of a bunch of different calculations that take all of the different variables into account and tell you, based upon all the variables available to us, here's what it looks like the weather is going to be like in X amount of time. Right, So, whenever we're talking about forecasts, obviously we have to worry about what are the current conditions and how far out

are we trying to predict the weather? And on TV you might see five or seven or even these days sometimes ten. Yeah. Like if you go to weather dot com, they have a ten day forecast, which I always think is hilarious. And the reason I think it's hilarious is

here's how those predictions work. You take all the information available to you, you run it through your computer model, which factors in these different variables and gives you sort of a percentage of probability of what your weather is going to be like in the next let's say hour.

What if you want to look two hours ahead, Well, then what they do is they take the prediction that they made for an hour from now and extrapolate from there, saying, well, if in fact the weather is what we think it's going to be like in an hour, this is what should look like two hours from now. Well, if you want to look at three hours from now, well let's take what the results were for two hours from now and extrapolate again, and that's what we think it's going

to be three hours from now. Extend that out to ten days. Yeah, and it's going to become less and less reliable, Yes, because you're basing your predictions upon the results of a previous set of predictions, not upon a

previous set of actual conditions. Right, So when you're tracing it all the way back and your starting point is right now, well, clearly, the further out we look, the more unreliable the information is going to be, the more likely some other variable that we have not anticipated will play a larger role or a smaller role, and that is going to affect the overall outcome of the of

what will actually happen. The forecast is the same, but the actual thing we experience might be very different, which is why if you're planning a picnic and you've got ten days out from it and you're looking at the weather and it says it's going to be absolutely perfect, don't bet the house on it. Yes, that's not necessarily true. Not to discredit numerical weather predictions, because a lot of

science and time goes into it. Yeah, but it's still you know, It's the way that I see modern meteorology is that over time we have continually built upon basically what our ancestors did and just gotten it's gotten more scientific, we've gotten better instruments, but it's still looking for patterns. Yeah, exactly right. So you might look at the patterns of

when all of these conditions are in play. Out of the last one hundred times that that happened, this is how the weather turned out, and we're going to break it down. So maybe eighty days out of those one hundred days where the conditions were similar to today's, it didn't rain at all. It was perfectly sunny, so eighty out of one hundred it was lovely. The other twenty days it rained and it was just steady rain, and that's all there is to it. This is a super

oversimplified version of what could happen. This is what would lead you to say there's a twenty percent chance of rain, because he would say, all right, now, the last hundred times the weather was exactly like it is today, twenty of those times it rained, eighty of those times it did not. Therefore, there is a twenty percent chance that

it will rain. That again is oversimplifying the way it works, but generally speaking, that's kind of how they come to those determinations, And in fact, there are ways of bolstering the NWP by using something called model output statistics, which is I kind of just talked about it a little bit. I'll just go ahead and touch on it right now.

It's essentially doing what we were talking about, looking at a specific region and the specific outcomes of days that had similar conditions to the one you're looking at right now, and then you're kind of making an educated guess based upon a computer model and actual localized history. I got that clear to something up for a lot of people. I sure hope so because I've just kind of gone with it. You know, I've just seen, oh, twenty percent chance of rain, okay, and never really thought about what

goes into determining that. Well. And I know that there's some people who had, you know, when they saw twenty percent chance of rain, they thought it meant, oh, it's going to rain over twenty percent of the forecast area, which means that you know, that would be more like scattered showers. That's really what scattered showers means. When you're scattered showers, it means that parts of the forecast area are expected to get rain, but it will not necessarily

rain over the entire forecast area. But if you hear twenty percent chance of rain, it does not mean that eighty percent of the forecast area is going to be dry and the other twenty percent it's going to be wet. Nor does it mean it will rain for twenty percent of the day. In fact, that's part of the problem. A prediction of precipitation, the good old pop, the pop so pop. That requires a time element to it as well.

It doesn't mean anything without a time element. So if you say there's a twenty percent chance to rain, you also need to have an element of time attached to that to make it meaningful. So twenty percent chance to rain over the next six hours, then you know, all right, So it's not saying that's going to be twenty percent chance to rain or it's not gonna rain twenty percent of the day, just that for the next six hours there's a twenty percent chance it will be raining in

the forecast area. We will be back with more weather technology after this quick break, so I hope that demystifies some of it. Also, we can talk about radar. One of my favorite things to talk about. Radar is awesome,

favorite character on mash me too. Yeah, well, I think it's so adorable, right, Yeah, it's hard not to feel for him, and the fact that he can anticipate everything his commanding officer wants, and he can even say what the commanding officer is saying before the commanding officer has finished a sentence is obviously a key part of that operation. But we're talking about actual radar, using radar to detect weather.

You've probably heard Doppler radar when looking at a weather report, like, well, let's look at the Doppler radar and see where this precipitation is moving in. Doppler radar for weather is different from Doppler radar used by say, police officers, who are

trying to detect if you are speeding. The Doppler radar that meteorologists use actually shoots out radio waves in very short bursts called pulses, and then the radar listens for any echoing pulses coming back to the antenna, and the short pulses indicate not just the presence of something out there, but whether it's moving and which direction is it moving in. Is it moving toward the radar station or away from it.

If a Doppler radar receiver detect waves of a higher frequency, the precipitation particles are moving toward the radar exactly, and lower frequencies they're moving away. Yes, Because what's happening is it's similar to a Doppler shift. And anyone who's ever heard a vehicle with a siren go past yeah, is familiar with this. It's a higher pitch as the vehicles coming toward you, and a lower pitch as it's moving away. What's actually happening is as a vehicle is moving toward you,

the sound waves it's emitting are being compressed. Now that compression creates a higher frequency, which means we detect higher pitch. As the vehicle passes, those frequencies are elongated, which means a lower pitch. Same thing is true with the radar accept Instead of it being a pitch, it's a radio frequency. If so, a higher frequency will tell you, yeah, something's coming towards you, and a lower frequency will tell you

something's moving away from you. And also the time between when the pulse goes out and when you detect it tells you the distance from the radar detection system and the precipitation. So you could even say there's a storm system that's five miles to the west, it's moving easterly at this speed because you've detected it through a series

of pulses. If you have enough radar detection stations, you can even describe the shape of the weather system and talk about how some areas are more intense than others. You can get all of that information from this approach, and it's amazing how this thing works. First of all, it's super high power. These radar stations are they're they're generating or they're transmitting I should say, at four hundred and fifty thousand watts. So your typical microwave oven is

a thousand watts. Wow, so you need a four hundred and fifty of those to equal one of these radar systems. So four and fifty thousand watts, and the pulse lasts so short as to be unimaginable. It is point zero zero zero zero zero one five seven seconds long, or one point five seven times ten to the minus six seconds. So if you hear the weatherman on TV bragging about

Doppler radar, there's a reason. It's very impressive. Yeah. I mean, you're sitting at a burst of radio signals at such a fraction of a second that it is again impossible to even imagine. Meanwhile, then it listens for a longer period, and by longer I mean relatively longer. It's still a fraction of a second. It's point zero zero zero nine

nine eight four three seconds. So it shoots out a pulse, listens for a little while, so it can detect when the pulse comes back and what frequency it's at, so it knows whether or not a body is moving toward it or away from it, and then it does it again. But that means, with that amount of time and the comparatively large amount of time of listening, for every hour of operation, the radio or the radar antenna is only

shooting out signals for seven seconds out of an entire hour. Wow, that means for the fifty nine minutes fifty three seconds, it is not sending out a signal. It is listening. So for almost a full hour it's listening and only for seven seconds is it actively shooting out a signal. Can you mentioned it a conversation for someone who talks seven seconds out of an hour, it would I any conversation with me would last like a decade and before

you could get a word in edgewise. Yeah, it's it's pretty amazing, and you usually would have one of these stations shooting out these radio bursts at different angles of elevation. These are called elevation slices, and when you go through the entire range, you get what was called volume coverage pattern or VCP, and that's what tells you what the activity is, not just at ground level, but up in

the atmosphere as well. Toper radar can also detect tornadoes. Yeah. Yeah, if if the particles switch from moving toward and then away over a small distance, there's a good chance it could be a tornado. Yeah, we know a lot about those here in the southeast too. We get a lot of tornadoes, not as many as places in the you know, like in the Midwestern states, things like you know, Oklahoma and stuff. I mean, you guys get tornadoes even more frequently than we do, but we get them pretty serious.

Actually this year hasn't been too bad. No, but there was one in November, yeah, which is weird because typically we get them in the spring. Yes, usually between March and June. That's kind of like our let's play it easy. Yeah, but you don't wash that on anybody. So no, I have been through a close call with a tornado while wearing Renaissance Festival gear. That sounds surreal. That was my final day when I did my first run at the

festival in two thousand and one. Wow. Yeah, we had a really massive thunderstorm and at one point someone said that there was a tornado a tornado watch, but not a tornado warning watch, being that the conditions for a tornado forming are present, warning being that a tornado has actually been spotted in the region, in case you were wondering. So now let's talk about satellites and meteorology. So the computers are really good for building out those models and

giving us predictions. The double radars really good at tracking precipitation. What do weather satellites do well, they're keeping an eye on global weather patterns. But there are two different types of weather satellites and they do this in different ways. So one is the geostationary weather satellite. Now, geostationary weather satellites maintain their relative position over a specific point on

the Earth. They are at a very high orbit over the equator and they're always looking at the same thing because their orbit is at the same speed as Earth's rotation, not really the same speed, but relative speed. Because it's able to stay in that same point over that part of the Earth, and so they have to be on an equatorial orbit and they have to be at a particular altitude for this to work. It's great because it means they can keep an eye on a specific region.

It's lousy because one, they're really far away, so the instrumentation you have to put on the satellites has to be incredibly sophisticated in order to get good readings from that altitude. Plus they have a limited view, right, They're always looking at one part of the Earth. They can't see anything else outside of that view. Always geostationary yep. So the other type you have are satellites that are in a polar orbit around the Earth. Polar orbits are interesting.

So if you think of the Earth on its axis, the polar orbit is going parallel to the axis of the Earth. It's going perpendicular to the equator. So you would think of it as going from north to south and then south to north because once it crosses the south pole, you can only go north at that point. That's the only direction left to you, and it goes in that circle, which means these satellites get a full view of the entire Earth, because the Earth is rotating

while it's going in this orbit north south orbit. But it also means that you only get a look at the same part of the Earth twice in a twenty four hour period, since once every twelve hours, you could always put another satellite up there, and that way you could get you put it on the opposite side of the Earth where it's in the same orbit, and then you get a look every six hours, just one from one satellite and then six hours later one from another satellite.

But you also get to see everything on the planet, So there's your trade off is that you get a more comprehensive view, but you don't get a consistent view of any one part of the Earth with these kind of weather satellites. So a lot of weather surfaces depend upon both, yeah, so it's good to have both, yeah.

And typically they carry devices called radiometers, which usually have a small telescope or some sort of antenna, a scanning device of some sort, and one or more detectors that can pick up visible, infrared or microwave radiation, and they use that to take measurements of the Earth and send that down to the planet's surface, so that weather stations around the world can take that data and crunch it and figure out what the heck is going out on out there when the frogs are raining from the sky

apart from amphibious assault, and all of those measurements are actually done through little electrical voltages which then get digitized, so transformed into digital information before transmitted down to Earth, because you know, zapping electricity through space down to the planet, it's not the most efficient way of getting information across You certainly don't want to have a power chord stretch all the way there. That would just be such a pain,

very inefficient. Yeah. Also with aircraft patterns. Yeah, and if you don't have geostationary orbit, it gets wrapped up around the planet pretty quickly. Yeah. We will conclude our two part episode series about weather attack after this quick break. So how do meteorologists do things like predict temperature, like

predict highs and lows and that kind of stuff? For this I went to a website that was written by a meteorologist named Jeff Haby, and boy howdy, did it suddenly dawn on me how much more complicated this was than I had even anticipated. But according to Haby, he looks at everything from thermal advection, wind speed, cloud cover, dew point, and the number of daylight hours expected for that region in order to come up with the prediction for the high temperature of the day in the low

temperature of the day. So what the heck does all that mean? So thermal advection, what is that? That refers to the transportation of heat by a moving fluid. So typically the stuff that affects the advection include the strength of wind, So how hard is the wind blowing in that region? The temperature gradient between the warmer and colder areas.

So if one area is warmer than the other, is it warmer by like a couple of degrees or is it more significant than that is ten degrees fahrenheit, that would be a much larger gradient, right, And the angle between the wind direction and the temperature gradient, if that angle is more narrow, you're going to see a greater thermal advection, meaning you'll see more temperature changes moving into an area from a different region. So that's just advection. That's a lot of play. The other one that you

other term you might be a little confused by. I mean, wind speed makes sense, cloudcover makes sense daylight hours. All of that makes sense, but what about dew point? That refers to the temperature at which air must be cooled at constant barometric pressure for water vapor to condense. So that temperature, again is dependent upon things like the actual air pressure, right, and so the dew point changes based

upon those other factors as well. So all those have to be taken into account before a meteorologist can forecast what the temperature is going to be the next day. This is why we're so happy to have those complicated computers now, because if you were to keep track of

this yourself, you probably go bonkers. And then we have like the idea of the probability of precipitation, which we kind of talked about already, but generally speaking, there's some weather services that will only predict rainfall if it's expected to be over a certain amount, like point two five millimeters. If it's going to be less than point two five millimeters, it doesn't even register as rainfall in predictions. You would say there's a zero percent chance or whatever, if that's

what you think is going to be the accumulation. Some other ones are like, no any rain at all counts if it's one drop of rain it rained in that region, so it really depends upon the service. But that we already talked about the percentages and what those means, so hopefully that clears things up. And again that kind of goes into that concept of model output statistics, where you correct for your predictions based upon past conditions for a

particular region. All of this comes together to create the weather report that you see. So I think the real takeaway here is it's incredible the amount of schooling and expertise a meteorologist has to have in order to do his or her job properly. Yes, right, like, because you see how complicated this is, and you start to have an appreciation of all right, they said it was a sixty percent chance of rain. I brought my umbrella and

never rained. Now you realize, well, when you're talking about the system, this complicated and this unpredictable, something that can change dramatically just because something you did not anticipate happened, you start to appreciate more the challenge that they have to do their jobs properly. So give your meteorologist a

hug and say thank you, because this stuff is hard. Yeah, and my you know if weather is the state of the atmosphere from day to day, and the atmosphere is super complex, you know, it's it's my favorite analogy from our article on our website about meteorologies, that the atmosphere is like a soup with too many cooks. Yeah. Yeah, there's a lot at play and so many different variables are working behind the scenes to give you a simple

a simple weather forecast that is easily digestible. Yeah. This is also why when you hear about supercomputers running weather simulations, that's why you need a supercomputer because of this too many cooks. I mean, it takes a lot to make us stew. I hope, I hope at least some of you are singing along now, But yeah, it's it really does explain why you need that massive amount of computing power just to do something that you would think would

be fairly simple. You know, you're thinking like, oh, it's like six or seven factors, and then you realize, oh, wait, no, there are these other things that also have an effect, and in some cases a measurable and meaningful effect, not just a potential effect. And it really does drive home that it's amazing we can have relatively accurate weather predictions in the first place. And also it makes me kind of sad that I no longer I used to be

on television with a local weather guy. He did a show at five thirty in the morning, and I would show up on television and do a gadget segment with him, and it was great. He was very nice, and his ability to break down complicated concepts of weather in a way that was helpful to people so that they could plan their day was really amazing, especially when you start really thinking about all the things that come into play

to make that, you know possible. So our hats are off to you meteorologists out there, keep doing the good work. I look forward to learning more about you know, when we when we figure out even more details about the complexities of the atmosphere and perhaps are able to make even more accurate models, maybe we will one day reach the back to the future too level where minute by minute it tells you what the weather is going to be.

Of course, then I think they were actually suggesting that we would have weather control, which is a whole other thing that's opening and cannle worms. Yeah, I talked to Dylan that I said I had thought about doing a little discussion about weather control. But obviously we've gone pretty

long already. So what I will say about weather control is weather systems represent a huge amount of energy, and in order for us to affect or manufacture weather events on a large scale, we would have to be able to generate that amount of energy and pour it into the atmosphere in a way that actually does what we wanted to do. And we're so far away from any of those things that it's absolutely unrealistic to think of

weather control, even if you are a Cobra commander. Yeah, you know, going back to the beginning of this episode with that listener request for this, and yeah, their father said that in the sixties that they felt like the weather report was just a joke. And you fast forward to now and how you know, maybe some days you grab an umbrella and you don't need it, but that it's you know, you can track major weather patterns and

incoming storms. That we have a pretty good ability to track hurricanes and like flash floods and things like that. I can't imagine where I'll be in forty or fifty years. Yeah, the fact that we can get at least heads up on stuff before it becomes critical to us, is really important. I mean, Dylan, you probably remember it wasn't that long

ago here in Atlanta when we had the snow apocalypse. Yes, and because it was one of those things where the initial weather report suggested that the weather was going to miss the city and it didn't, that's an indication that, yeah, our predictions are not one hundred percent accurate, they're not infallible.

And it also taught us a valuable lesson, which is that even when you feel like there's a pretty good chance that you're going to miss out on that bad weather, it doesn't hurt to prepare because the alternative is to spend eight hours on two eighty five, even if it is an inch of snow, because it's Atlanta. Yeah, and because we don't have a system in place to deal with an inch of snow, and we got a lot of hills. None of us have snow tires. Why would you?

And you let out the private in the public sector at the same time, that was particularly bad. I remember I actually stayed here, not here, but in our old office location. I stayed there pretty much through the full day because it was like, I'm gonna take Martha, I'm gonna take the train. It's not gonna be a big deal.

It took me three hours to get home, usually would take me forty five minutes, and I was getting I got online, got ready to complain, and then I started reading messages for my friends who were stuck in their cars and had been for six hours. I thought, yeah, okay, we're going to back away from the community slowly. Kids stuck in school buses overnight. Yeah. Yeah, pretty rough stuff. So yeah, we're We're not perfect, but it is getting better, and it is pretty impressive to see the amount of

information you can get. I love, I mean I love. I find watching Doppler radar readouts to be fascinating, Like I could have that open on my desk all day if I if I didn't have other stuff I need to do. So Drees, thank you so much for sending that request in. It's a lot of fun to kind of read up on it and to go over Dylan, thank you for joining me in the studio. Thanks for having me greatly appreciate it. Well, that was it for WeatherTech,

at least from back in twenty sixteen. Again, I'll probably need to do an update to this whenever I do these classic episode intros naltros. I'm always reminded, Oh yeah, I should really revisit this. This is one of those. But if there are topics like new ones, or maybe there's a topic you think I should revisit that I haven't really talked about in a long time, you should let me know. And there are a couple of different ways of doing that. You can go to Twitter and

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