TechStuff Classic:Weather Tech, Part 1

How are weather predictions made? How does the tech used in meteorology work? And can we control the weather?

 

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Episode Transcript

Speaker 1 (00:04):
Welcome to tech Stuff, a production from iHeartRadio. Hey there,
and welcome to tech Stuff. I'm your host, Jonathan Strickland.
I'm an executive producer with iHeartRadio. And how the tech
are you? It is time for another classic episode of
tech Stuff. This episode that you're about to hear originally

(00:26):
published on April twentieth, twenty sixteen. Huh four twenty But no,
this has nothing to do with anything you know, blazy. No,
this has to do with weather technology. In fact, it's
called Weather Tech Part one, and that tells you what
next week's classic episode will be. So sit back and

(00:47):
enjoy WeatherTech Part one from April twentieth, twenty sixteen. Today
we're gonna talk about weather because of a listener request.
This comes from Dress Sayan and dree I am so
sorry if I mispronounced your name. I actually asked Dreese
how to pronounce this name, and I can only hope

(01:08):
I got close. But here's what Dreas had to say. Hey,
I just wanted to ask Slash request something about the podcast.
See a while back, I had a conversation with my dad.
He commented how amazing it was these days. He can
just check a website that will pretty accurately tell him
whether it's going to rain in the next few hours.
And where I said that, it doesn't seem like that's

(01:30):
amazing progress to me. After all, when he was a
kid in the sixties, they would report if it would
rain the next day, and now it's just that we've
got it down to a few hours instead of twenty
four hours ahead. He laughed and said the weather report
back then was pretty much a joke. Anyway, this gave
me a lot to think about, and it seemed like
something to learn about from the Tech Stuff podcast, because,
to be honest, I have no clue how weather is

(01:51):
accurately predicted. It's just always been there for me. So
we're gonna talk about weather forecasting, meteorology, the technology used
to make predictions, what those predictions actually mean. We're going
to break all that down. There will probably be at
least one or two references to how weather report. Weather

(02:14):
reports are still largely the work of some estimations and
best guesses, because, as it turns out, whether it's incredibly complicated,
but hopefully by the end of it, you'll have a
little bit more sympathy for meteorologists. Right right as opposed
to my friend who in college wrote an essay explaining

(02:34):
what level of hell meteorologists should inhabit based upon Dante's Inferno,
which was kind of funny, but also I'm sure meteorologists
find it less. So so let's start off with just
talking about the history of predicting weather, and really you
have to go all the way back to early human civilization, because,

(02:57):
as it turns out, one of the most important factors
that play a part in this is the fact that
we humans are pretty good at recognizing patterns. Right, So
when something happens over and over, we take note of it,
and we start to look at the other things that
are happening over and over, and then we start to
draw some hypotheses. For example, we might think that one

(03:19):
thing could cause the next thing, or we might think
one thing simply indicates the next thing is going to happen.
Here's a simple example. Let's say that you are a
shepherd and you notice that the flock of sheep act
in a certain odd way every time it's about to rain.
You might either come to the conclusion that the sheep

(03:41):
are able to sense the rain before it actually happens,
and therefore that as an indicator that is going to rain,
or you might come to the conclusion that, in fact,
the sheep are causing it to rain. That's probably not true.
There are two ways to take that. Yeah. Yeah, But eventually,
through these observations you start to eliminate possibilities and you
start to draw some conclusions. Now, in early human civilizations,

(04:04):
we're talking about very broad conclusions, things like you notice
that in general, the weather gets cooler as the year
goes on. You might not even have a year at
this point. You may just think, as time passes, the
weather gets cooler until it gets really cold, and after
it's really cold for a while, it starts to get
warm again, and then it gets really warm, and then

(04:24):
it gets hot, and then the whole cycle starts over.
And you may also notice that the stars the way
the stars are, you can tell that they are. It's
a slightly different view as this time goes on, and
you start to associate, oh, when the stars get into
this slow you know, this kind of configuration, It means
we're getting toward the time when we should really harvest food,

(04:48):
because we're about to go into the winter months and
otherwise we're going to lose everything we've been growing, or
when it's this time we should start planting food because
it's the best time for us to get a big yield.
Later on climate, Yeah, and you start to figure out
you build out a calendar based on this, and that
calendar would be fairly rough, you know, wouldn't necessarily be

(05:10):
reflective of an actual full year, but it would be
more like an indicator of what you should be expecting
in the next coming time. Right, So that's your basic
like big picture stuff, using things like the way animals
react or certain smells that you might detect before a rainstorm.
That would be sort of the more acute weather type

(05:32):
stuff as opposed to the seasonal type stuff. And you
start to draw those conclusions too, and together you start
building out general rules that tell you if this one
thing is happening, then here's what you should expect. This
sort of pattern recognition. And in fact, today some of
our data still relies on that principle. It's just that

(05:56):
we have way more information now at a much higher
precision than ancient humans did. And speaking of that, I
read that there are certain Aboriginal tribes that have been
observing their weather patterns for over eighteen thousand generations, so
that kind of gives you a sense of how far
back this goes. Yeah, and and of course, you know,

(06:18):
if you're talking about a very specific region, like a
very relatively small geographic area, you could have a pretty
accurate idea of what to expect based upon those sorts
of observations. They might not be presented in the super cool,
high tech way that modern meteorology tends to present it,

(06:42):
but that doesn't make it any less valid necessarily. It
may be a little more rough around the edges. But
if you can still tell me that, hey, in three
days we're going to get some rain, and three days
later it rains, and you do that reliably, that's pretty impressive. Right.
So if you want to start looking at people who
were really thinking about whether in kind of almost a

(07:05):
scientific sense, and one of the first people you would
have to look at his Aristotle, big brain Aristotle. He
was quite the thinker. He wrote about whether in Meteorologica,
and he came up with a bunch of hypotheses, some
column theories, I would say hypotheses, because none of these,

(07:28):
not all of these proved true. They came up with
some hypotheses about how stuff like rain and hail, and
wind and clouds and thunder and lightning and hurricanes. What
made them happen, how did they behave what were the
rules that governed them? And some of his ideas were
mostly right and some of his ideas were way off.
But the problem was without ways to measure the various

(07:52):
metrics associated with weather, it was kind of impossible to
say one way or the other. So for about two
thousand years, everyone kind of just went with it because
you didn't have any way of proving or disproving any
of the individual ideas. But you need a basis, Yeah,
you know, at least it was something. It was at

(08:13):
least something to work from. It was just it was
just a question of time. When would people develop tools
that would allow them to put these ideas to the
test and either see which ones are mostly right but
maybe need some tweaking, or in which ones you can
just completely throw out the window, Which brings us up
to the Renaissance, one of my favorite time periods. As

(08:35):
it turns out, spend a lot of time there. Our
listeners can't see. But right now Jonathan has a handlebar mustache,
a giant handlebar mustache, because the character I play in
the Georgia Renaissance Festival has such a mustache, and I
will be performing as that character the day after we
record this episode. It's opening weekend for the Georgia Renaissance Festival.

(09:00):
Would you say that someone might have a handlebar mustache
in the fifteenth century, around the time of German philosopher
Nicholas of Cusa, It's quite possible. I mean, there's no
reason they could not have one. It's not like there
were social taboos about such things. Yeah. So this philosopher,
Nicholas of Cusa, designed a device to measure the amount

(09:23):
of moisture in the air, and we call these hygrometers.
These are it's really kind of a way of measuring humidity,
which here in Atlanta you can pretty much just says
it's humid. It's so humid. Yeah, the humidity in Atlanta
is brutal, to the point where I have friends who
come in from Texas, where the temperatures in Texas can

(09:45):
get twenty degrees hotter than it gets here in Atlanta.
But because Texas has relatively low humidity through most of
the state, they think the weather here is way worse, like,
way more difficult to deal with, But how do you
measure that? And he came up with an interesting idea.
Now there's there's no indication that he ever built the

(10:05):
device he came up with, but he said, what you
do is you take a set of balanced scales, so
you know what those look like. They have a little
dish on either side, and on one side you put
a large amount of wool, and on the other side
you put some weights. He said stones. Other people later
on said discs of wax didn't really matter. It just

(10:26):
had to be a counterweight of some sort. Now, the
purpose of the wool is to soak up moisture in
the atmosphere, which would make the wool get heavier. This
is what Nicholas was saying. Like, the wool will get
heavier as it soaks up water from the air, and
you'll be able to tell that because the scales will
start to shift and you'll see that the side with

(10:48):
the wool will start to get heavier. Then if it
dries out, if the weather gets dry, the wool will
start to lose moisture. It will evaporate, and you'll start
to see that side of the scale moving up. It'll
get lighter. Now, he never built that, But another big
thinker of the Renaissance did get around to it, Leonardo

(11:08):
da Vinci. Yes, he did everything. Yeah, when he wasn't
building helicopters or designing tanks, which he never built, but
he did design. He designed a tank, and he designed
a really weird I think, gosh, it was something like
a thirty three barrel gun, didn't he I think a

(11:29):
diving suit as well. Pretty much any any sort of
thing that in the Renaissance would sound like it's science fiction.
She had some sort of hand in. He probably has
a primitive tablet schematic somewhere. Yeah. Yeah, he probably at
one point came out to his patrons and showed a
wooden slate and talked about how if you ran your

(11:51):
fingers across it you could you could paginate through. And
then he'd say, I think you're gonna love it, and
maybe even did a one more thing. So that was
the first kind of weather related instrument that people were
really thinking about. Another would come in the seventeenth century

(12:12):
early sixteen hundreds, usually put around sixteen oh three, when
physicist Galileo Galile created a thermoscope, which is sort of
a predecessor to a thermometer. And it was a pretty
simple idea. So you start with a container that has
a small amount of liquid in it, usually water. That's
your base. And then you also have a kind of

(12:32):
a hollow tube of glass that ends in a bulb,
so like a larger bulb at one end and open
on the other end. And you could do something like
warm the bulb if you want too, in your hands.
But then you would put the bulb. You would put
the tube into the small container of water. The bulb
would be suspended above it. Usually the hollow straw like

(12:58):
tube would be long enough, you know, several inches long.
You could then observe that as the temperature of the
bulb changed, the level of water in the tube would
either go up or go down. And this is because
the air inside the tube is either expanding or contracting,
depending upon whether it's heating up or cooling down. And

(13:19):
this wasn't a thermometer, but it was. It was interesting,
and it was once again a start. Yeah. Later on
someone looked at Galileo's little invention and said, what if
we put like markings on the tube so you could
say how many steps up or down the tube it went.
Then we could even give indications of how much warmer

(13:42):
or cooler. You could say it's four steps warmer or
four steps cooler. That became the basis of the thermometer.
So and that didn't take long. It was within about
fifty years that you had the first working thermometers. Following
this kind of proof of concept thermoscopy, there was also
there is the Galilean thermometer. Are you familiar with these?

(14:04):
I am not. You've probably seen one. They are the
cylindrical glass They're usually very decorative for for like home
office desk ers, and but these glass tubes, they are cylindrical.
Typically inside they have these these little glass blown glass
balls that contain their own liquid. Often it's a liquid

(14:25):
that has dye in it, so they're blue or green
or red or whatever. And each one has a little
weight attached to it that has a temperature. And what
happens is the balls represent different densities of water, and
the temperature of the glass tube will change the density

(14:45):
of the water inside the glass tube. And then you'll
see whichever ball is at the bottommost of the tube
the glass tube, as that represents the general temperature, and
they tend to be between like you know, like about
five degrees aparts, he might have sixty five degrees seventy
seventy five degrees eighty that kind of thing. So whicheveryone's
at the lowest point. That's the temperature of the water,

(15:07):
thus the temperature of the area surrounding it. I tend
to be used, like I said, as decorations for desks
and stuff. Galileo actually did not invent that, but some
of his students did. It was several of his students,
so that's why it's called a Galilean Thermometer's neat. Yeah. Yeah,
it's a very pretty way of seeing, generally speaking, what

(15:28):
temperature the tube is and therefore probably what temperature the
surrounding area is. Keeping in mind that water changes temperature
more slowly than something like a room would, so it
wouldn't be reflected immediately, but it's still kind of interesting.
We'll be back with more about weather technology after this

(15:48):
quick break. Then we have the This is a very
important tool in predicting the weather. So barometer is all
about predicting, or not predicting, but measuring atmospheric pressure. So

(16:11):
first thing, just in case you weren't aware, the atmosphere
exerts pressure on us. It pushes down. Gravity is technically
pulling down on the atmosphere. So the lower you are
to the surface of the air, like the closer the
lower down and elevation you are, the more pressure you
feel from atmosphere. This is why as you climb a

(16:31):
mountain or you get on a plane, you experience lower
amounts of air pressure. It's also why you have to
pressurize aircraft that fly it pretty high altitudes, otherwise you
would suffer some pretty rough effects. And on the Earth's
surface the force of gravity. Due to the force of gravity,
the pressure is about fourteen point seven pounds per square inch. Yeah,

(16:55):
that's a sea level. Yeah, that's what we call an
atmosphere of pressure. Right one atmosphere pressure, you look at
it at sea level. Specifically, you're looking at it at
sea level at fifty nine degrees fahrenheit, which is fifteen
degrees celsius. You have to be very specific because temperature
will change pressures as you warm up air. Typically this
is just a general rule of thumb. When something warms up,

(17:18):
that means molecules are moving. That's the energy of motion. Ultimately,
you're making these molecules move faster and that's kind of
what heat looks like. So as molecules of air move
around more, they spread out more, it becomes less dense.
So that would change the atmospheric pressure as well. That's

(17:39):
why you have to take temperature into account. When you
talk about one atmosphere of pressure. That's very specific. It's
at sea level at that temperature, that's one atmosphere. So
that's that's kind of interesting anyway. The first person to
actually create a barometer was a guy by the name
of Evangelista Torricelli, and his first invention people just called

(18:02):
Toricelli's tube, which doesn't seem very dignified. No, it needs
a special name. Yeah, but Tori Chelli's tube, it wasn't
quite the barometer yet. What he was doing was he
was actually experimenting with the concept of vacuums, like creating
a vacuum within a tube or some other container. He
was just it was one of those things where we

(18:23):
didn't fully understand what that was, how it worked, and
so he did this experiment. He was actually friends with Galileo,
and Galileo said, hey, Evangelista, I got an idea for you.
Why don't you take one of those tubes you've been
working with, and fill it with mercury and use that
in your vacuum experiments. Will be a lot easier to
see than some other liquid. And Tori Chelli says, all right,

(18:45):
I'll give it a shot. So he took a four
foot long glass tube and he filled the glass tube
with mercury so it was closed on one end, open
on the other, and then he inverted the tube into
a dish, and the dish had a little bit of
mercury at the bottom of it. And it showed that
this the fact that the top of the tube, you know,
like the mercury went all the way up this four
foot tube. The liquid didn't just come rushing out and

(19:08):
spill everywhere, right, because the vacuum is what held it
in place. And he says, look, see, I was so smart.
This shows that there's something working here. We're gonna really
explore this. But then he noticed something else that was
really interesting. He noticed that despite the fact that the
tube could stay upright and the liquid would stay in
there from day to day, there were variations and how

(19:31):
high the mercury would be in the tube. And it
wasn't just sinking down. It's not like it was leaking
over the course of a week. So like you come
back and it's a couple inches lower, and then the
next day it's a couple inches lower. It wasn't like that.
Some days it was actually higher. And he started thinking, well,
what the heck would cause the mercury to go up
or down this tube? The atmosphere that's it. The atmospheric

(19:53):
pressure pressing down on the liquid in the dish. That's
what determined whether the well, that's what to the height
of the mercury inside the tube. So on days with
higher atmospheric pressure, it pushes down on that exposed liquid
within the dish and it forces that liquid to go
up the tube, and so the height of the liquid

(20:15):
inside the tube goes up. On days where atmospheric pressure
is lower, some of that liquid comes down and starts
filling up the dish until it reaches that kind of equilibrium.
And then he's so he said, hey, this shows that
the atmosphere itself exerts pressure. And not only that, but
the pressure is not consistent day to day. It can change.

(20:37):
And in sixteen forty four Torchelli built the first mercury barometer.
So now he was building something specifically to measure this thing,
because before he was really demonstrating the concept of vacuums.
So now we've got the barometer, we've got the thermometer,
we've got the hygrometer, essential things. Yeah, these are the
basics for taking measurements about weather. And at that point

(21:02):
it was really the start of gathering enough information so
that meteorology, the science of meteorology, could actually exist, right
because now we could not just observe patterns, we could
actually quantify what was happening. And by quantifying it, we
could get to this level of precision where we could

(21:23):
start to draw more specific conclusions as to what would
or would not happen based upon current conditions. So, all
that being said, we still have some issues predicting weather.
So why is that? Well, like I said before, it's complicated.

(21:43):
So here's the thing. Our atmosphere is fluid. It's a gas,
but it behaves via fluid dynamics. Dylan, have you ever
studied fluid dynamics, I don't believe. So I studied them
in physics and they are rutally difficult to comprehend because
it can get so there's so many factors that can

(22:06):
affect a fluid, so and the Earth has a whole
bunch of them happening at once. Right. First of all,
there's this big ball of plasma that's about eight and
a half light minutes away from us. It's called the Sun. Yeah,
you know, on nice days you might even get a

(22:28):
glimpse of it. So the Sun provides obviously a ton
of energy to the Earth and so we So the
Earth absorbs a lot of solar radiation and that can
affect fluid dynamics because you've got a lot of heat
coming into a system. On top of that, you've got
the Earth. Earth's not standing still, the Earth is rotating.
That rotational force creates other fluidic effects in the atmosphere.

(22:54):
We'll talk about those specifically when we get to high
and low pressure systems. You've got gravity, which is pulling
down on the fluid, so that's another force that's in play.
You've got differences in surface temperature on the Earth, so
you've got areas where it's very cold versus areas that
are very hot. That in turn affects the atmosphere and

(23:15):
can change things around. You have air currents a big
deal there. That's also partially due to the rotation of
the Earth. You've got mountain ranges which can act as
like a windbreaker for certain things that changes the way
weather patterns happen. Lots of things that are all in play,
and some of these are localized, and some can concern
large portions like air movement. Oh yeah, yeah, some of

(23:37):
them are. Some of the effects of these can be
felt hundreds of miles from where the thing happened, right,
which makes it even harder because as a lady person,
you sit there and think, all right, well, you know,
because I can't see any clouds on the horizon, I
think tonight's going to be all right, And then you
could have a very fast moving system coming in due

(24:00):
to something that happens well out of sight. It ends
up creating a lot of things that could be counterintuitive,
depending upon what you have at your disposal. Like, of course,
the more information you have, the better conclusions you can
draw in general, assuming that you also know what you're
talking about. So let's talk about some of these things.

(24:22):
These different major components that shape weather, like atmospheric pressure.
So we just talked about that with barometers, But what
does that mean? So what is happening? Well, I talked
about how you have warm air that has air moving
around a lot. That means it ends up spreading out,
it becomes less dense than cold air. You probably have

(24:42):
heard the phrase that warm air rises in cold air sinks,
not entirely accurate as to what's going on. What's really
happening is cold air is more dense than warm air,
so cold air comes to take up the space that
warm air had, which forces warm to go up. So
it's not so simple as warm air rises, cold air sinks.

(25:04):
It's more like, you know, if you've got these big
heavy weights at the top, then they're going to come.
They want quote unquote want, there's no desire, but they
have a tendency to want to move downward, forcing the
lighter stuff to go upward. That's pretty much what's happening here.
So when you're talking about our atmosphere, you have to

(25:27):
keep in mind it's three dimensional. It's not on a
flat plane. That's easy to forget when we look at
weather reports, because we're looking typically at a flat map,
right that has a bunch of stuff like it's got
little flags all over it and little lines around it,
and h's and l's, and you're wondering what you know,
maybe there's some clouds in there too, and but typically

(25:49):
you're looking at a two dimensional representation. But really you
have to remember that weather is a three dimensional phenomenon,
so that makes it a little more complicated. Also, you
got to remember the water cycles. So cold air can't
hold onto moisture the way warm air can. All right,
when you have warm air as close to the surface.

(26:11):
Let's say you've got some nice, warm, moist air close
to the surface of the planet, and cold air is
sinking down forcing the warm air up. As the warm
air rises, it's going to start to cool and as
it cools, it can no longer hold onto the moisture
that it had, which means the moisture starts to condense,
water vapor begins to condense. This is how you get

(26:33):
clouds and ultimately how you get stuff like precipitation. So
understanding that's important. So now let's imagine way up in
the atmosphere, at the top level of where our weather happens,
we have these massive air currents now in cases where
air currents are converging together, so you've got two air

(26:56):
currents that are meeting up. They start to force air
out of the way. Now air can't go any further
up to go down, it has to go down. That's
the only place to go. So that air coming down
increases air pressure at that location. You have air moving
down towards the surface of the Earth pushing down, your

(27:17):
air pressure goes up. So an area of high pressure.
You know what kind of weather you typically see in
an area of high pressure? Clear, dry weather, Yes, exactly.
So when you have high pressure system, it's typically pushing
the moisture out of the way. It's it's it tends
and we have to use phrases like tens or words

(27:38):
like tens because it's not every case is equal. But
it tends to be cooler, it tends to be sunny,
it tends to have less wind than low pressure systems.
So this high pressure system creates pleasant weather. Low pressure
systems are different. Oh and also if you were to

(28:00):
view this from the sky, like you're above this high
pressure system, and if you could see air, first of all,
that would be a nightmare. But if you could, you
would see that the air is not just coming down
like a column. It's not like it's not like you
turn on a spigot of water and water just falls
straight down. It's actually turning as the air is sinking right,

(28:25):
as this high pressure system forces air downward, and it
actually moves in a clockwise direction, which is funny because
I was looking at Dylan a second ago and making
a twisting motion, but I was doing counterclockwise. But no,
it moves in a clockwise direction. This is, by the way,
due to the rotational force of the Earth in part.
So you've got this rotating clockwise system that's pushing air downward.

(28:48):
That's your high pressure. We got a little bit more
about WeatherTech to talk about before we get to that.
Let's take another quick break. So that's your nice weather,
low pressure. I think you can probably take a wild

(29:09):
guess it's gonna mean crummy weather. Yeah, this is where
you're getting clouds and rain, and typically you're talking about
air being pulled upward. So why is air getting pulled upward? Well,
remember I was talking about those those currents up in
the upper atmosphere where they were converging together and forcing

(29:30):
air downward. If the currents are moving apart from each other,
if they're diverging, they create sort of a vacuum effect
over that region, and that starts to pull air upward,
creating an area of low pressure. Warm air from the
surface gets pulled upward, it starts to cool down and
the water vapor condenses. That's where you start getting those

(29:51):
overcast days, the cloudiness, the rain. And on top of that,
you're creating since it's a low pressure system, you're creating
the opportunity for some pretty hefty winds to move in. Right,
Because air is always going to move from an area
of high pressure to an area of low pressure. That's
just pure fluid dynamics. It makes a lot of sense

(30:12):
if you've got like imagine that you have two water
balloons connected to each other, all right, and they are
in equilibrium, so they're equally full, not totally full, but
equally full. If you're to squeeze one of those, creating
an area of high pressure, it forces the water to
go to the area of relatively lower pressure. Right, You're

(30:35):
forcing water into that second water balloon. Same thing is
true with low pressure systems. You've got a low pressure area,
that means any area around it has higher pressure, air
is going to want to move into the area of
lower pressure. That's where you get winds coming in and
it can get pretty breezy. So this one, if you

(30:57):
were to look overhead and view the air, it would
be rotating in a counterclockwise or whiter shins if you
are Shakespearean direction, and the air would be coming into
the low pressure system as opposed to coming out like
in high pressure. It would all be moving outward in
that clockwise direction, with low pressure inward in a counterclockwise direction. Now,

(31:21):
the reason why I even bring this up is because
it's important to understand how high at pressure and low
pressure affect weather. So things like the wind speed, the
potential for precipitation or lack of precipitation, all of those
would play a part. And it's important for you to
know what the pressure is of that region in order
for you to make any sort of forecast. So the

(31:43):
barometers would be the tools you would use to get
those those measurements. Now, the old style barometers, the mercury ones,
use fluid to indicate changes in pressure, sort of like
what we were talking about with Evangelista's barometer, simply just
looking to see where the level is. So area of
high pressure pushes the liquid further up, you would say

(32:04):
that pressure is rising and weather it's probably going to
be pretty nice. In fact, if you ever have seen
one of those old school barometers, it probably has like
sunny like a little drawing of sunshine toward the top
of it where the level goes up. If the if
the glass is falling, if the mercury is going down
the tube, then that would suggest low pressure, which suggests cloudy,

(32:28):
nasty weather. But we also have other types of barometers.
In fact, not a lot of people use the mercury
ones anymore. Don't know. If you know this, Dylan, mercury
is not the best thing to use. It's a little toxic. Yeah,
it'll drive you crazy, you'll go mad as a hatter,
but yeah. They they're also aneroid barometers, which were invented
in the nineteenth century eighteen hundreds. In other words, these

(32:50):
have a tiny little metal box and the sides are
all made out of a flexible metal, and changes in
pressure either push the sides of the box inward or
allow the sides of the box to flex outward. That
in turn is connect to tiny little levers which are
connected to a needle. And then you look at your device.

(33:13):
It can look like a little stop watch actually, and
you see where the needle is and that tells you
where the atmospheric pressure is at right, or you could
use digital barometers, which have little pressure sensitive transducers that
essentially do the same thing. They're just doing it with
a transducer as opposed to an actual physical metal box.

(33:36):
And how do we talk about these measurements, Well, it
depends upon what system you're looking at. But typically weather men,
meteorologists I should say weather people. I suppose that sounds
like a good term. Yeah, yeah, weather people inclusive term. Yeah,
a meteorologist is probably more accurate, but they use They

(33:57):
tend to use millibars to describe atmospheric pressure, but in
the US. Here in the US, we sometimes refer to
inches of mercury, because darn it, we like that system.
The standard scientific unit is the pascal or PA, and
then there is, of course the one atmospheric pressure type approach.

(34:19):
That's not terribly useful if you're talking about tiny changes
in atmospheric pressure, like yeah, it's a point zero zero
zero six atmosphere change doesn't help you very much. To me.
It's kind of like measuring temperatures and celsius. It works
great if you're boiling water, but if you're doing anything else,

(34:39):
Celsius to me is just it's too brute force an
approach to describe boil water. So that's perfect, right, that's
really whenever I go by Dylan's desk, it's just a
pot of boiling water and some photos on a screen
and that's about it. So then we have temperature and
moisture that those are the other two really big components.

(35:01):
So a large body of air that has a similar
temperature and moisture throughout that body of air is called
an air mass. So when two air masses are near
one another, they are separated by a thing called a front. Right.
So you've heard of cold fronts and warm fronts obviously, right,
So we'll focus on the United States. We have four
major types of air masses that affect our weather here

(35:23):
in the United States. This is not the way it
is everywhere. These are the four that in general affect
our weather. So you've got continental polar air masses cold
and dry yep. Continental tropical air masses hot and dry, yes,
which by the way, only happened in the summer and

(35:43):
come up from Central America. That makes sense. Yeah, Then
you have maritime polar cool and moist yeah. And boy,
I'm so sorry for you people out there who hate
the word moist, and then maritime tropical, warm and moist.
There it is again. Yeah, so your content in minal
polar air masses, those tend to come from our friends

(36:04):
to the North Canada. They ship us their poutine, they're
Tim Horton's coffee, and their continental polar air masses. Don't
bring up Tim Hortons. I'm still bummed that there's not
one here. I'm actually still look Canada. I poke a
lot of fun, but I fully admit Tim Hortons is
a phenomenal chain, a national treasure. I would welcome it

(36:26):
with open arms to come here to Atlanta. Just throwing
it out there. Your continental tropical, like I said, comes
up through Central America and typically only affects our weather
in the summer. Maritime polar that tends to come from
the far northeast. So we're talking like in the New

(36:47):
England that area maritime tropical pretty much everywhere else. And
by tropical when we say hot or warm and moist,
we don't necessarily mean like it feels like you're in
the Caribbean. It just means not cold. Right, So the
fronts tell us what sort of air is moving into

(37:07):
an area, so a warm front. First of all, they
tend to move pretty slowly. Warm fronts are not known
for moving through an area quickly, and they bring lots
of rain because warm fronts are pushing out cold air.
So imagine you've got a massive cold air in an area.
A warm front is coming in that warm air when
it encounters the cold air that's already in that region,

(37:30):
it's the warm air's inclination is to kind of go
up the cold air like a ramp because again, the
cold air is more dense, right, so the warm air
can't just push it out of the way. The warm
aare is less dense than the cold air, but it
can start to go up on top of it, which
means the warm are starts to cool down exactly, and
that's why we get rain at the edge of a

(37:52):
warm front. So they move pretty slowly because warm air
just doesn't push cold air out very efficiently, and we
get a lot of precipitation. Cold fronts where cold air
replaces warm air, move faster and tend to have intense
but short thunderstorms and other precipitation. As the front moves
in and the weather tends to clear up pretty shortly thereafter.
The reason for this is, imagine you've got a massive

(38:15):
cold air moving in, you have warm air in the region.
The cold air is going to almost act like a
shovel scooping up that warm air, pushing it up into
the upper levels of the atmosphere, of the lower level
of the atmosphere, but the upper side of it, which
cools that air down very quickly. Because of that quick cooling,

(38:37):
you get things like bigger rainstorms thunderstorms, but they tend
to happen very quickly, and then once the front has
moved through, things are okay again. Spend a summer in
Atlanta and you will see this phenomenon repeatedly. Right like
you there was. There are times where if it's a

(38:59):
particularly humid month, you might be able to set your
watch by when the thunderstorm is going to come through.
Any extreme extreme versions of it as well, not not
not disaster level, but you'll see quick intense thunderstorms with
hail and heavy rains and they will be gone in
an hour or two yep, and then it just becomes

(39:19):
a steam bath for the city. That's Atlanta most of
the time. Yeah, but it's particularly bad about an hour
after a thunderstorm. It's probably the most miserable Atlanta feels, right,
because it's just it's like walking into a steam room. Yes,
So again, the reason for that fast violent weather is

(39:40):
just the speed at which that warm air is being
pushed up and cooled down so that it can no
longer hold on to all this moisture that was once
part of it, and it has to go somewhere, so
it lands on us. So that's kind of interesting. They're
also stationary fronts. Stationary fronts are when two fronts just
kind of collide and that's it. They're just there. It's

(40:03):
gonna stick around for a while. You'll have a lot
of rain. Typically sounds like the traffic jam of fronts. Yeah.
And then there's occluded fronts, and that's when a warm
front gets caught between two cooler air masses. So the
warm front gets pushed up and we get a lot
of intense thunderstorms with occluded fronts. Two. Hope you enjoyed

(40:26):
that classic episode of tech stuff from twenty sixteen, Weather
Tech Part One. Obviously next week we will have Weather
Tech Part two as our classic episode, so make sure
you come back and listen to that. If you have
suggestions for future topics for tech Stuff, please reach out
to me and let me know. You can go over
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(40:48):
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(41:12):
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