April 21, 2016 • 31 mins
How are weather predictions made? How does the tech used in meteorology work? And can we control the weather?
Learn more about your ad-choices at https://www.iheartpodcastnetwork.com
See omnystudio.com/listener for privacy information.
Mark as Played
Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:04):
Technology with tex Stuff from Hastuff. Hey there, and welcome
to Tech Stuff. I am your host, Jonathan Strickland, and
now I'm going to bring you the exciting conclusion about
whether Technology Dylan has joined me for this episode. This
(00:25):
was a show that we recorded all in one go,
but it turned out to be too long for a
single episode, so we've broken it up and that means
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
(00:50):
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 roswald uh concy right right,
swamp gas and weather balloons and uh, you know, weather
balloons do more than just act as a subplot in
(01:13):
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 radio SOND,
which is a bettery powered device that can measure altitude,
(01:34):
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 sia uh. But sometimes you know you
need to have that GPS element there too. And getting
(01:55):
this information from the atmosphere is really important because it
can tell you about how conditions may soon change on
the ground. Um. It's pretty interesting actually to ever if
you've ever had a chance to to look at some
of the data pulled from these because you you see
how different conditions in the atmosphere are compared to what
(02:15):
we experience here, including some pretty intense winds at higher altitudes. UM.
So we've got all this information being collected. Uh. 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
(02:36):
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 was the temperature,
how much humidity was in the air, what was the
wind speed, were there any higher low pressure systems nearby?
(02:57):
What 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 um, and we can supplement that with
more information as we learn more about the weather. Then
(03:18):
we would end up using that to help us make
some predictions about how weather weather it might be in
the future. And we to do that, really we use
computer models. Uh. Typically we would build what it's called
a numerical weather prediction model, the NWP. So this is
(03:39):
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
(04:00):
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 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
(04:23):
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 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
(04:46):
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
(05:07):
hours from now. Extend that out to ten days. Yeah,
and it's going to become less and less reliable, Yes,
because you're 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
(05:30):
the way back and you're starting point is right now, like, 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. Uh, and that is going to
affect the overall outcome of the fourth of what will
(05:52):
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. That's not necessarily true. Not to
discredit numerical weather predictions, because a lot of science and
(06:16):
time goes into it, but it's still you know, it's
it's the way that my I see modern meteorology is
that over time we have continually built upon basically what
our ancestors did, and it's gotten it's gotten more scientific,
we've gotten better instruments, uh, but it's still looking for
patterns yeah, exactly right. So you might look at the
(06:39):
patterns of when all of these conditions are in play.
Out of the last hundred times that that happened, this
is how the weather turned out. Uh, And we're gonna
break it down. So maybe eighty days out of those
one days where the conditions were similar to today's, it
didn't rain at all. It was perfectly sunny, So eight
(07:01):
out of a 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 chance of rain, because
he would say, all right, now, the last hundred times
(07:22):
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 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 that there are ways of bolstering the NWP
(07:44):
by using something called model output statistics, which is I
kind of just talked about 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 emmeler
conditions to the one you're looking at right now, and
then you're kind of making an educated guess based upon
(08:06):
a computer model and actual localized history. But 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 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 chance of rain, they thought it meant, oh,
(08:28):
it's going to rain over of the forecast area, which
means that you know that 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. Um. But if you
hear twenty percent chance of rain, it does not mean
(08:49):
that of the forecast area is going to be dry
and the other twenty percent is gonna be wet, Nor
does it mean it will rain for twenty of the day.
In fact, that's part of the problem, uh, a prediction
of precipitation, the good old pop, the pop so pop
that that requires a time element to it as well.
(09:10):
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 chance to rain over
the next six hours, then you know, all right. So
it's not saying that's gonna be chance to rain or
it's gonna not gonna rain of the day, just that
for the next six hours there's a twenty percent chance
(09:31):
it will be raining in the forecast area. 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 nash Yeah, well, I
think it's so adorable, right, It's hard not to feel
for him, and the fact that he can anticipate everything
(09:54):
his commanding officer wants, and he can even say what
the commanding officer is saying for the commanding officer has
finished a sentence. Obviously a key part of that operation
um so, but we're talking about actual radar, using radar
to detect weather. You've probably heard Doppler radar when looking
(10:15):
at a weather report, like, well, let's look at the
Doppler radar and see where the this, 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
(10:38):
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?
Um is it moving toward the radar station or away
from it? If a Doppler radar receiver detect waves of
(11:01):
a higher frequency, the precipitation particles are moving towards the
radar exactly, and lower frequencies they're moving away. Yes, because
what's happening is it's similar to a Doppler shift. And
and anyone who's ever heard a vehicle with a siren
go past is familiar with this. It's a higher pitch
as the vehicles coming toward you and a lower pitch
(11:24):
as it's moving away. What's actually happening is, as the
vehicle is moving towards you, the sound waves it's emitting
are being compressed. Now that compression creates a higher frequency,
which means we detect a 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
(11:45):
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
(12:06):
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 UH.
If you have enough radar detections UH stations, you can
even describe the shape of the weather system and talk
about how some areas are more intense than others. You
(12:29):
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. Uh. These radar stations are are they're
they're generating or they're transmitting I should say at four
hundred fifty thousand watts. So your typical microwave oven is
(12:50):
a thousand watts, So you need a four hundred and
fifty of those to equal one of these radar systems.
So four and fifty thou wats. And the pulse lasts
so short as to be unimaginable. It is point zero
zero zero zero zero seven seconds long, or one point
(13:11):
five seven times ten to the minus six seconds. So
if you hear the weather man on TV bragging about
Doppler radar, there's a reason. It's very impressive. Yeah. I
mean you're sitting at a 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
(13:34):
a longer period, and by longer I mean relatively longer.
It's still a fraction of a second. It's point zero
zero zero four three seconds. So it shoots out a
pulse listens for a little while, so I 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
(13:56):
it again. But that means with that amount of time
and the 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. That means for the fifty nine
(14:16):
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 seven seconds is actively shooting out
a signal. A conversation for someone who talks seven seconds,
it would I any conversation with me would last like
a decade before you could get a word in edgewise. Yeah,
(14:39):
it's uh, 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 vc P. That's what
(15:00):
tells you what the activity is, not just at ground level,
but up in the atmosphere as well. Toppler radar can
also detect tornadoes. Yeah. Yeah, if if, if the particles
switch from moving toward and then away over a small distance, uh,
there's a good chance it could be a tornado. Yeah,
we know a lot about those. Here in the southeast too.
(15:22):
We get a lot of tornadoes, not as many as
places in the uh, you know, like in the Midwestern States,
things like you know, Oklahoma and stuff, and you guys
get tornadoes even more frequently than we do, but we
get them pretty seriously. Actually this year hasn't been too bad,
but there was one in November, yeah, which is weird
because typically we get them in the spring. Yes, um,
(15:44):
usually between March and June. That's kind of like our
let's play it easy. Yeah, but you don't waste that
on anybody, So no, I have. I have been through
a close call with a tornado while wearing Renaissance festival year.
That sounds surreal. That was my final day when I
(16:04):
did my first run at the festival in two thousand one. 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. Our present warning being that a
tornado has actually been spotted in the region, in case
(16:26):
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, Uh, well,
they're they're keeping an eye on global weather patterns. But
there are two different types of weather satellites and they
(16:49):
do this in different ways. So one is the geostationary
weather satellite. Now, geo stationary 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
they're always looking at the same thing because their orbit
is at the same speed as Earth's rotation um not
(17:13):
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
(17:35):
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. So the other type you
have are satellites they are in a polar orbit around
the Earth. Polar orbits are interesting. So if you think
(17:55):
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. UM, and it goes in that circle,
(18:17):
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 UM. 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. UM. You can always put
(18:38):
another satellite up there, and that way you could get
you know, put it on the the opposite uh 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
(18:58):
get you get a more conference of view, but you
don't get a consistent view of any one part of
the Earth with these kind of weather sellites. So a
lot of of weather services depend upon both yeah, and
typically they carry devices called radiometers, which usually have a
small telescope or some sort of antenna, a scanning device
(19:20):
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
(19:41):
from amphibious assault UM, 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's not the most efficient way of getting information across UM.
And he certainly don't want to have a power chord
(20:02):
stretch all the way there. That would just be such
a pain. Yeahs with aircraft patterns, and if you don't
have geostationary orbit, it gets wrapped up around the planet
pretty quickly. Yeah, 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
(20:22):
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, uh,
he looks at everything from um thermal advection, wind speed,
cloud cover, de point, and the number of daylight hours
(20:45):
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 infection, what is that
that refers to the transportation of heat by a moving fluid.
So typically the stuff that affects the infection include the
strength of wind, So how hard is the wind blowing
(21:07):
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, like ten degrees fahrenheit,
That would be a much larger gradient, right, And the
angle between the wind direction and the temperature gradient, If
(21:28):
that angle is more narrow, you're going to see a
greater thermal infection, meaning you'll see more temperature changes moving
into an area from a different region. So that's just infection,
that's all I play. Uh, the other one that you
other term you might be a little confused by. I mean,
wind speed makes sense, cloud cover makes sense, daylight hours,
(21:51):
All of that makes sense. But what about do point?
That refers to the temperature at which air must be
cooled at constant barometric pressure for water vapor to and dense.
So that temperature again has depended upon things like the
actual air pressure right um, and so the dow point
changes based upon those other factors as well. So all
(22:12):
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 the probability of precipitation,
which we kind of talked about already, but generally speaking,
(22:33):
there's some weather services that will only predict rainfall if
it's expected to be over a certain amount, like point
to five millimeters. If it's going to be less than
point to five millimeters, it doesn't even register as rainfall
in predictions. You would say there's a zero percent chance
or or whatever, if that's what you think is going
(22:55):
to be the the accumulation. Some other ones are like,
no any rain at all counts. If it's one drop
of rain it rained in that in that region. Um
so it really depends upon the service. But uh that
we already talked about the percentages and what those means,
so hopefully that clears things up. And again that kind
(23:16):
of goes into that concept of model output statistics, where
you 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
I think the real takeaway here is it's incredible the
(23:38):
amount of of schooling and expertise a meteorologist has to
have in order to do his or her job properly,
right like, because you see how complicated this is, and
you start to have an appreciation of all right, and
they said it was a six chance of rain, I
brought my umbrella and never rained. Now you realize, well,
(24:00):
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
(24:21):
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 our article on our website,
UM about meteorology is that the atmosphere is like a
(24:42):
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 uh uh supercomputers running weather simulations,
(25:05):
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. Um. 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,
(25:25):
it's like six or seven factors, and 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. Um. And it really does drive
home that it's amazing we can have relatively accurate weather
(25:45):
predictions in the first place. Um. 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
(26:11):
in a way that was helpful to people so that
they could plan their day was really amazing, especially when
you 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
(26:32):
about you know, when we when we figure out even
more details about the complexities of of the atmosphere and
perhaps are able to make even more accurate models. Um,
maybe we will one day reach the back to the
future to level where minute by minute it tells you
what the the weather is going to be. Of course,
then I think they were actually suggesting that we would
(26:54):
have weather control, which is a whole other thing handle 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
(27:15):
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
(27:37):
to think of weather control, even if you are a
Cobra commander going you know, going back to the beginning
of this episode with that listener request for this and
that 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,
(27:58):
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 uh, and in 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 a at least heads up on stuff
(28:21):
before it becomes critical to us is really important. Uh.
I mean, Dylan, you probably remember it wasn't that long
ago here in Atlanta when we had the snow apocalypse,
and because it was one of those things where the
initial weather reports suggested that the weather was going to
miss the city and it didn't. That's an indication that, yeah,
(28:43):
our predictions are not accurate, they're not infallible. Uh. 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 gonna miss out on that bad weather, it
doesn't hurt to prepare because the the alternative is to
spend eight hours on two eight five, even if it
(29:06):
is an inch of snow. Because it's Atlanta, 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. Yeah, that was particularly bad. I remember
I actually stayed here, not here, but in our our
old office location. I stayed there pretty much through the
(29:30):
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, Okay,
we're gonna back away from the community slowly. Kids stuck
(29:50):
in school buses overnight. Yeah, pretty rough stuff. So yeah,
we're we're not 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
(30:11):
to do. So Dree, thank you so much for sending
that request in. There's a lot of fun to kind
of read up on it and to go over at Dylan,
thank you for joining me in the in the studio.
Thanks for having greatly appreciate it. If you guys have
suggestions for future episodes of tech Stuff, write me let
me know what you think. I am actually reading those
emails for a while, Dylan. Are you familiar with outlooks
(30:34):
clutter folder? I am. I deleted mine. You know what,
that was a wise decision, Dylan, because it turned out
that all of my listener mail for the last five
months has been going to my text stuff in box
clutter folder. So I discovered that last week and I
have since been going back and trying to answer as
many of those as possible. I started foolishly with the
(30:56):
most recent and started working my way back. So if
you wrote me a few months ago and you're wondering
why I never bothered to respond, it's because I haven't
gotten to your email yet. But I'm still working my
way through. But if you have a suggestion for a
future episode, right me, I've been keeping track of those,
will be covering them shortly. And also you can get
in touch with me on Facebook or Twitter to handle
at both of those. Is Tech Stuff hs W and
(31:18):
I will talk to you again really soon for more
on this and bousands of other topics. Is it how
stuff works dot com
Technology with tex Stuff from Hastuff. Hey there, and welcome
to Tech Stuff. I am your host, Jonathan Strickland, and
now I'm going to bring you the exciting conclusion about
whether Technology Dylan has joined me for this episode. This
(00:25):
was a show that we recorded all in one go,
but it turned out to be too long for a
single episode, so we've broken it up and that means
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
(00:50):
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 roswald uh concy right right,
swamp gas and weather balloons and uh, you know, weather
balloons do more than just act as a subplot in
(01:13):
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 radio SOND,
which is a bettery powered device that can measure altitude,
(01:34):
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 sia uh. But sometimes you know you
need to have that GPS element there too. And getting
(01:55):
this information from the atmosphere is really important because it
can tell you about how conditions may soon change on
the ground. Um. It's pretty interesting actually to ever if
you've ever had a chance to to look at some
of the data pulled from these because you you see
how different conditions in the atmosphere are compared to what
(02:15):
we experience here, including some pretty intense winds at higher altitudes. UM.
So we've got all this information being collected. Uh. 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
(02:36):
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 was the temperature,
how much humidity was in the air, what was the
wind speed, were there any higher low pressure systems nearby?
(02:57):
What 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 um, and we can supplement that with
more information as we learn more about the weather. Then
(03:18):
we would end up using that to help us make
some predictions about how weather weather it might be in
the future. And we to do that, really we use
computer models. Uh. Typically we would build what it's called
a numerical weather prediction model, the NWP. So this is
(03:39):
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
(04:00):
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 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
(04:23):
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 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
(04:46):
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
(05:07):
hours from now. Extend that out to ten days. Yeah,
and it's going to become less and less reliable, Yes,
because you're 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
(05:30):
the way back and you're starting point is right now, like, 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. Uh, and that is going to
affect the overall outcome of the fourth of what will
(05:52):
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. That's not necessarily true. Not to
discredit numerical weather predictions, because a lot of science and
(06:16):
time goes into it, but it's still you know, it's
it's the way that my I see modern meteorology is
that over time we have continually built upon basically what
our ancestors did, and it's gotten it's gotten more scientific,
we've gotten better instruments, uh, but it's still looking for
patterns yeah, exactly right. So you might look at the
(06:39):
patterns of when all of these conditions are in play.
Out of the last hundred times that that happened, this
is how the weather turned out. Uh, And we're gonna
break it down. So maybe eighty days out of those
one days where the conditions were similar to today's, it
didn't rain at all. It was perfectly sunny, So eight
(07:01):
out of a 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 chance of rain, because
he would say, all right, now, the last hundred times
(07:22):
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 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 that there are ways of bolstering the NWP
(07:44):
by using something called model output statistics, which is I
kind of just talked about 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 emmeler
conditions to the one you're looking at right now, and
then you're kind of making an educated guess based upon
(08:06):
a computer model and actual localized history. But 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 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 chance of rain, they thought it meant, oh,
(08:28):
it's going to rain over of the forecast area, which
means that you know that 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. Um. But if you
hear twenty percent chance of rain, it does not mean
(08:49):
that of the forecast area is going to be dry
and the other twenty percent is gonna be wet, Nor
does it mean it will rain for twenty of the day.
In fact, that's part of the problem, uh, a prediction
of precipitation, the good old pop, the pop so pop
that that requires a time element to it as well.
(09:10):
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 chance to rain over
the next six hours, then you know, all right. So
it's not saying that's gonna be chance to rain or
it's gonna not gonna rain of the day, just that
for the next six hours there's a twenty percent chance
(09:31):
it will be raining in the forecast area. 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 nash Yeah, well, I
think it's so adorable, right, It's hard not to feel
for him, and the fact that he can anticipate everything
(09:54):
his commanding officer wants, and he can even say what
the commanding officer is saying for the commanding officer has
finished a sentence. Obviously a key part of that operation
um so, but we're talking about actual radar, using radar
to detect weather. You've probably heard Doppler radar when looking
(10:15):
at a weather report, like, well, let's look at the
Doppler radar and see where the this, 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
(10:38):
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?
Um is it moving toward the radar station or away
from it? If a Doppler radar receiver detect waves of
(11:01):
a higher frequency, the precipitation particles are moving towards the
radar exactly, and lower frequencies they're moving away. Yes, because
what's happening is it's similar to a Doppler shift. And
and anyone who's ever heard a vehicle with a siren
go past is familiar with this. It's a higher pitch
as the vehicles coming toward you and a lower pitch
(11:24):
as it's moving away. What's actually happening is, as the
vehicle is moving towards you, the sound waves it's emitting
are being compressed. Now that compression creates a higher frequency,
which means we detect a 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
(11:45):
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
(12:06):
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 UH.
If you have enough radar detections UH stations, you can
even describe the shape of the weather system and talk
about how some areas are more intense than others. You
(12:29):
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. Uh. These radar stations are are they're
they're generating or they're transmitting I should say at four
hundred fifty thousand watts. So your typical microwave oven is
(12:50):
a thousand watts, So you need a four hundred and
fifty of those to equal one of these radar systems.
So four and fifty thou wats. And the pulse lasts
so short as to be unimaginable. It is point zero
zero zero zero zero seven seconds long, or one point
(13:11):
five seven times ten to the minus six seconds. So
if you hear the weather man on TV bragging about
Doppler radar, there's a reason. It's very impressive. Yeah. I
mean you're sitting at a 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
(13:34):
a longer period, and by longer I mean relatively longer.
It's still a fraction of a second. It's point zero
zero zero four three seconds. So it shoots out a
pulse listens for a little while, so I 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
(13:56):
it again. But that means with that amount of time
and the 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. That means for the fifty nine
(14:16):
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 seven seconds is actively shooting out
a signal. A conversation for someone who talks seven seconds,
it would I any conversation with me would last like
a decade before you could get a word in edgewise. Yeah,
(14:39):
it's uh, 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 vc P. That's what
(15:00):
tells you what the activity is, not just at ground level,
but up in the atmosphere as well. Toppler radar can
also detect tornadoes. Yeah. Yeah, if if, if the particles
switch from moving toward and then away over a small distance, uh,
there's a good chance it could be a tornado. Yeah,
we know a lot about those. Here in the southeast too.
(15:22):
We get a lot of tornadoes, not as many as
places in the uh, you know, like in the Midwestern States,
things like you know, Oklahoma and stuff, and you guys
get tornadoes even more frequently than we do, but we
get them pretty seriously. Actually this year hasn't been too bad,
but there was one in November, yeah, which is weird
because typically we get them in the spring. Yes, um,
(15:44):
usually between March and June. That's kind of like our
let's play it easy. Yeah, but you don't waste that
on anybody, So no, I have. I have been through
a close call with a tornado while wearing Renaissance festival year.
That sounds surreal. That was my final day when I
(16:04):
did my first run at the festival in two thousand one. 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. Our present warning being that a
tornado has actually been spotted in the region, in case
(16:26):
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, Uh, well,
they're they're keeping an eye on global weather patterns. But
there are two different types of weather satellites and they
(16:49):
do this in different ways. So one is the geostationary
weather satellite. Now, geo stationary 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
they're always looking at the same thing because their orbit
is at the same speed as Earth's rotation um not
(17:13):
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
(17:35):
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. So the other type you
have are satellites they are in a polar orbit around
the Earth. Polar orbits are interesting. So if you think
(17:55):
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. UM, and it goes in that circle,
(18:17):
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 UM. 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. UM. You can always put
(18:38):
another satellite up there, and that way you could get
you know, put it on the the opposite uh 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
(18:58):
get you get a more conference of view, but you
don't get a consistent view of any one part of
the Earth with these kind of weather sellites. So a
lot of of weather services depend upon both yeah, and
typically they carry devices called radiometers, which usually have a
small telescope or some sort of antenna, a scanning device
(19:20):
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
(19:41):
from amphibious assault UM, 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's not the most efficient way of getting information across UM.
And he certainly don't want to have a power chord
(20:02):
stretch all the way there. That would just be such
a pain. Yeahs with aircraft patterns, and if you don't
have geostationary orbit, it gets wrapped up around the planet
pretty quickly. Yeah, 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
(20:22):
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, uh,
he looks at everything from um thermal advection, wind speed,
cloud cover, de point, and the number of daylight hours
(20:45):
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 infection, what is that
that refers to the transportation of heat by a moving fluid.
So typically the stuff that affects the infection include the
strength of wind, So how hard is the wind blowing
(21:07):
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, like ten degrees fahrenheit,
That would be a much larger gradient, right, And the
angle between the wind direction and the temperature gradient, If
(21:28):
that angle is more narrow, you're going to see a
greater thermal infection, meaning you'll see more temperature changes moving
into an area from a different region. So that's just infection,
that's all I play. Uh, the other one that you
other term you might be a little confused by. I mean,
wind speed makes sense, cloud cover makes sense, daylight hours,
(21:51):
All of that makes sense. But what about do point?
That refers to the temperature at which air must be
cooled at constant barometric pressure for water vapor to and dense.
So that temperature again has depended upon things like the
actual air pressure right um, and so the dow point
changes based upon those other factors as well. So all
(22:12):
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 the probability of precipitation,
which we kind of talked about already, but generally speaking,
(22:33):
there's some weather services that will only predict rainfall if
it's expected to be over a certain amount, like point
to five millimeters. If it's going to be less than
point to five millimeters, it doesn't even register as rainfall
in predictions. You would say there's a zero percent chance
or or whatever, if that's what you think is going
(22:55):
to be the the accumulation. Some other ones are like,
no any rain at all counts. If it's one drop
of rain it rained in that in that region. Um
so it really depends upon the service. But uh that
we already talked about the percentages and what those means,
so hopefully that clears things up. And again that kind
(23:16):
of goes into that concept of model output statistics, where
you 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
I think the real takeaway here is it's incredible the
(23:38):
amount of of schooling and expertise a meteorologist has to
have in order to do his or her job properly,
right like, because you see how complicated this is, and
you start to have an appreciation of all right, and
they said it was a six chance of rain, I
brought my umbrella and never rained. Now you realize, well,
(24:00):
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
(24:21):
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 our article on our website,
UM about meteorology is that the atmosphere is like a
(24:42):
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 uh uh supercomputers running weather simulations,
(25:05):
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. Um. 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,
(25:25):
it's like six or seven factors, and 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. Um. And it really does drive
home that it's amazing we can have relatively accurate weather
(25:45):
predictions in the first place. Um. 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
(26:11):
in a way that was helpful to people so that
they could plan their day was really amazing, especially when
you 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
(26:32):
about you know, when we when we figure out even
more details about the complexities of of the atmosphere and
perhaps are able to make even more accurate models. Um,
maybe we will one day reach the back to the
future to level where minute by minute it tells you
what the the weather is going to be. Of course,
then I think they were actually suggesting that we would
(26:54):
have weather control, which is a whole other thing handle 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
(27:15):
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
(27:37):
to think of weather control, even if you are a
Cobra commander going you know, going back to the beginning
of this episode with that listener request for this and
that 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,
(27:58):
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 uh, and in 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 a at least heads up on stuff
(28:21):
before it becomes critical to us is really important. Uh.
I mean, Dylan, you probably remember it wasn't that long
ago here in Atlanta when we had the snow apocalypse,
and because it was one of those things where the
initial weather reports suggested that the weather was going to
miss the city and it didn't. That's an indication that, yeah,
(28:43):
our predictions are not accurate, they're not infallible. Uh. 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 gonna miss out on that bad weather, it
doesn't hurt to prepare because the the alternative is to
spend eight hours on two eight five, even if it
(29:06):
is an inch of snow. Because it's Atlanta, 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. Yeah, that was particularly bad. I remember
I actually stayed here, not here, but in our our
old office location. I stayed there pretty much through the
(29:30):
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, Okay,
we're gonna back away from the community slowly. Kids stuck
(29:50):
in school buses overnight. Yeah, pretty rough stuff. So yeah,
we're we're not 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
(30:11):
to do. So Dree, thank you so much for sending
that request in. There's a lot of fun to kind
of read up on it and to go over at Dylan,
thank you for joining me in the in the studio.
Thanks for having greatly appreciate it. If you guys have
suggestions for future episodes of tech Stuff, write me let
me know what you think. I am actually reading those
emails for a while, Dylan. Are you familiar with outlooks
(30:34):
clutter folder? I am. I deleted mine. You know what,
that was a wise decision, Dylan, because it turned out
that all of my listener mail for the last five
months has been going to my text stuff in box
clutter folder. So I discovered that last week and I
have since been going back and trying to answer as
many of those as possible. I started foolishly with the
(30:56):
most recent and started working my way back. So if
you wrote me a few months ago and you're wondering
why I never bothered to respond, it's because I haven't
gotten to your email yet. But I'm still working my
way through. But if you have a suggestion for a
future episode, right me, I've been keeping track of those,
will be covering them shortly. And also you can get
in touch with me on Facebook or Twitter to handle
at both of those. Is Tech Stuff hs W and
(31:18):
I will talk to you again really soon for more
on this and bousands of other topics. Is it how
stuff works dot com
TechStuff News
Hosts And Creators
Oz Woloshyn
Karah Preiss
Popular Podcasts
Stuff You Should Know
If you've ever wanted to know about champagne, satanism, the Stonewall Uprising, chaos theory, LSD, El Nino, true crime and Rosa Parks, then look no further. Josh and Chuck have you covered.
Dateline NBC
Current and classic episodes, featuring compelling true-crime mysteries, powerful documentaries and in-depth investigations. Follow now to get the latest episodes of Dateline NBC completely free, or subscribe to Dateline Premium for ad-free listening and exclusive bonus content: DatelinePremium.com
Las Culturistas with Matt Rogers and Bowen Yang
Ding dong! Join your culture consultants, Matt Rogers and Bowen Yang, on an unforgettable journey into the beating heart of CULTURE. Alongside sizzling special guests, they GET INTO the hottest pop-culture moments of the day and the formative cultural experiences that turned them into Culturistas. Produced by the Big Money Players Network and iHeartRadio.