Speaker 1: Text with technology with tech Stuff from stuff works dot com.
Speaker 1: Hey there, and welcome to tech Stuff. I'm your host,
Speaker 1: Jonathan Strickland. I'm a senior writer here with how stuff
Speaker 1: works dot com, and today I wanted to talk about
Speaker 1: something I got to do. Those pretty cool just last week,
Speaker 1: well last week as of the time I'm recording this,
Speaker 1: I got to go visit the Weather Company to do
Speaker 1: some interviews about meteorology and also ibm s Watson platform.
Speaker 1: And it was a really cool experience to actually get
Speaker 1: to walk around and see the various people who work
Speaker 1: on weather science and try to figure out what was
Speaker 1: the weather doing right now and was it going to
Speaker 1: do next. I even managed to cause some problems for
Speaker 1: the Weather Channel, but that wasn't entirely my fault. Uh
Speaker 1: Now to explain us, the Weather Channel and the Weather
Speaker 1: Company used to be the same entity, but then IBM
Speaker 1: acquired the product and technology divisions of the Weather Company
Speaker 1: and they bought those sections, but they didn't buy the
Speaker 1: television broadcast business. So now they are two independent businesses.
Speaker 1: One of them is run by IBM, the other one
Speaker 1: is its own standalone weather broadcast service. That being said,
Speaker 1: they still work very closely together. The Weather Channel still
Speaker 1: gets a lot of its data and it's information from uh,
Speaker 1: the Weather Company, so it's not like they are completely
Speaker 1: independent of each other, and they both still exist in
Speaker 1: the same building. They both are located out of the
Speaker 1: same headquarters building here in Atlanta, Georgia. So there is
Speaker 1: a Weather Channel studio that is in part of this building,
Speaker 1: and there's the Weather Company offices that's on different floors
Speaker 1: of the building, and UH they kind of co occupy
Speaker 1: space even though they are no longer corporately speaking anyway
Speaker 1: the same entity. So I thought it'd be fun to
Speaker 1: do an episode about meteorology and weather models. This is
Speaker 1: gonna be a two part episode because I have to
Speaker 1: cover the science behind weather first and then talk about
Speaker 1: meteorology to let you understand how meteorologists base their forecasts
Speaker 1: off of weather conditions. You have to understand the complexities
Speaker 1: of whether before you can really get a grip on
Speaker 1: what it is that meteorologists do. And so in order
Speaker 1: to do that, this episode is gonna be a little
Speaker 1: less about tech and more about science in order for
Speaker 1: us to have a deeper understanding of meteorology. In the
Speaker 1: next episode, I should I should also mention We've covered
Speaker 1: this topic in Tangential Ways and Older Tech Stuff episodes,
Speaker 1: but it was more than overdue for a revisit. So
Speaker 1: that's why we're going to talk about it today. We're
Speaker 1: gonna really look at how weather systems actually work. Uh.
Speaker 1: And before I get too far, I guess I should
Speaker 1: actually explain what I meant when I said I caused
Speaker 1: some problems for the Weather Channel. So while I was
Speaker 1: at their headquarters, I was getting ready to shoot a
Speaker 1: video interview with a man named Dale Eck, who is
Speaker 1: the director of the Weather Forecast Center for the Weather Company.
Speaker 1: So this guy is the head meteorologist in charge. He's
Speaker 1: been doing work in meteorology for thirty years, and he
Speaker 1: has a desk that's very close to the broadcast studio
Speaker 1: for the Weather Channel. The broadcast studio has glass walls,
Speaker 1: so you can see right through the walls. If you
Speaker 1: ever watch a broadcast on the Weather Channel and they
Speaker 1: shoot from inside the studio, you'll see people walking in
Speaker 1: the background. You'll see desks and monitors and lots of
Speaker 1: of colorful imagery because people have got a lot of
Speaker 1: weather maps up in the background, so all of that's real.
Speaker 1: Those are the actual people who work at the company. Uh,
Speaker 1: and that's where we were shooting our videos. We were
Speaker 1: shooting off to one side of this studio, and while
Speaker 1: we're getting ready to shoot, we had set up the camera.
Speaker 1: I was miked. We had a shotgun mike so that
Speaker 1: we can pick up Mr X his his contributions. We
Speaker 1: were off to one side of the studio, so we're
Speaker 1: up against where the glass walls are, but we weren't
Speaker 1: directly across from where the cameras were set up. Um,
Speaker 1: they did have sets where they could pivot around where
Speaker 1: we would have essentially been in the background for those
Speaker 1: those shots if they had set something up, but they
Speaker 1: were mostly shooting directly against the back wall of the
Speaker 1: studio and we were on one of the sidewalls. So
Speaker 1: we're getting ready to shoot, and one of the the
Speaker 1: employees over at the Weather Company very helpfully pointed out
Speaker 1: a bank of light switches that were in control of
Speaker 1: production lights. So flipping those switches would turn several lights
Speaker 1: on in the area we were standing in That would
Speaker 1: end up providing a lot more light for our video,
Speaker 1: and that is really important if you're shooting video, you
Speaker 1: need good lighting. So after being told about them, we
Speaker 1: turned them on. We being my producer, turned them on,
Speaker 1: and you know, he was essentially told to do it,
Speaker 1: so that's what he did. And it didn't take very
Speaker 1: long before a floor manager for the Weather Channel, very
Speaker 1: calmly walked up and asked us to knock that off.
Speaker 1: Although I should say she was incredibly friendly and professional.
Speaker 1: She wasn't mean about it at all, but explained that
Speaker 1: the light that we had created was bleeding into the set.
Speaker 1: You know, it's a glass wall, lights just passing right
Speaker 1: through it, so it was affecting the shot for the
Speaker 1: actual Weather Channel, you know, the nationally televised Weather Channel broadcast.
Speaker 1: So my little YouTube video that I was shooting was
Speaker 1: impacting a nationally broadcast television scene. So that was a
Speaker 1: little bit of a Oopsie Daisy moment for me and
Speaker 1: my team. The nice thing is it was probably pretty
Speaker 1: subtle and it probably didn't have that big of an
Speaker 1: impact at all, but still it made us feel like
Speaker 1: we were kind of jerk faces. And if you were
Speaker 1: watching the Weather Channel last week or this would that
Speaker 1: would have been, um, you know, this is June right now,
Speaker 1: so it would have been June Thursday. If you were
Speaker 1: watching the Weather Channel, you know, trying to keep up
Speaker 1: to date with Tropical Storm Cindy, and you were wondering,
Speaker 1: why is the lighting going all crazy in this broadcast?
Speaker 1: That was us are bad, But I have to really
Speaker 1: thank everyone who works for the Weather Channel and the
Speaker 1: Weather Company. They were very generous with their time and
Speaker 1: they gave us lots of leeway to shoot really cool video.
Speaker 1: So it was a great visit and it helped me
Speaker 1: appreciate the complexities of meteorology on a deeper level. So
Speaker 1: let's now talk about weather forecasting. It's an interesting business.
Speaker 1: At a very very high level, like a super simplistic level.
Speaker 1: Weather forecasting, at least in the recent past, involved taking
Speaker 1: lots of observations, comparing those observations of present conditions to
Speaker 1: things that had happened before in the past, researching what
Speaker 1: followed those similar conditions when they did happen before, and
Speaker 1: then making a guess as to what is going to
Speaker 1: happen next based upon past experience. That's a drastic oversimplification,
Speaker 1: and really it's saying that it's about pattern recognition, and like,
Speaker 1: let's say, if you notice that when the temperature goes
Speaker 1: up at a certain time of day, with these other
Speaker 1: factors in place, the chance of rain increases drastically based
Speaker 1: upon past experience. You might use that to help forecast
Speaker 1: the weather and say there's a good chance that's going
Speaker 1: to rain later today because these other factors are at play,
Speaker 1: and other times when that has happened, it's rained. But
Speaker 1: let me give you a more simple example about how
Speaker 1: this might work out. Let's say you've got some basic
Speaker 1: meteorological gear, like some sensors, a barometer, wind speed, indicator,
Speaker 1: wind direction. You know how much humidity is in the air.
Speaker 1: You know the temperature because you've got a thermometer, all
Speaker 1: these sort of things. These are the typical sensors you
Speaker 1: would find at a weather observation point. You've kept a
Speaker 1: log book of weather for this particular location that goes
Speaker 1: back two decades, so you've got twenty years of information
Speaker 1: at your disposal, twenty years of collections of data points
Speaker 1: and what was actually happening with the weather. You make
Speaker 1: your observation in the morning, you note the temperature, the
Speaker 1: air pressure, You've got all these different factors, and then
Speaker 1: you look at your log books and you look for
Speaker 1: days that are similar to the conditions you are currently observing.
Speaker 1: Then you look to see what happened later on those
Speaker 1: previous days. So if you had one hundred mornings that
Speaker 1: are similar to the conditions of the morning you are
Speaker 1: concerned with, like this morning, you wake up, this morning,
Speaker 1: you take readings, you find one other, one other examples
Speaker 1: in your log book that are similar to today, and
Speaker 1: then you notice that on seventy of those one days
Speaker 1: it rained. You could say there's a seventy chance of rain.
Speaker 1: That seventy of the time, when conditions were the way
Speaker 1: they are right now, it rained. Of those days where
Speaker 1: the conditions were exactly the way they are right now,
Speaker 1: it did not rain. And I don't really mean exactly.
Speaker 1: I guess I should say approximately, because weather is incredibly
Speaker 1: complicated and to have two weather systems behave exactly the
Speaker 1: same way under the same circumstances is pretty unlikely. But this,
Speaker 1: again is a drastic oversimplification of how weather forecasts work.
Speaker 1: It does give you a basic idea of the the
Speaker 1: principle behind meteorological forecasts, at least until more recently we
Speaker 1: get into weather simulation and huge amounts of data processing.
Speaker 1: Today that gets a lot more sophisticated than just what
Speaker 1: are the conditions today and what happened on previous occasions
Speaker 1: when those conditions were present. But keep in mind meteorology
Speaker 1: is constantly evolving. It has ever reached a perfect level status,
Speaker 1: as anyone who has depended upon a weather forecast knows,
Speaker 1: you've probably in the past looked at a weather forecast
Speaker 1: and said, oh, there's no chance of rain, and then
Speaker 1: a thunderstorm pops up. Well, that's because weather is really
Speaker 1: complicated and sometimes a hyper local event can occur that
Speaker 1: is impossible to really predict when you're looking at, say
Speaker 1: a regional weather forecast, because your fidelity doesn't get that small.
Speaker 1: You can't predict everything that happens within that region with
Speaker 1: perfect accuracy. You're giving more of an overall look for
Speaker 1: the region as a whole. So it gets really complex.
Speaker 1: There are a lot of different variables, and there's a
Speaker 1: lot of different technology that goes into gathering the information
Speaker 1: about those variables and then crunching those numbers to make
Speaker 1: some meaning out of it, which is why it's an
Speaker 1: ideal topic or text stuff. Now, if we are to
Speaker 1: understand really how meteorology works, we've we've got to take
Speaker 1: a deep looking at a look at whether or not
Speaker 1: a deep looking that makes no sense, but a deep
Speaker 1: look at whether. We at least need to get as
Speaker 1: deep in understanding for whether as we can in a
Speaker 1: casual podcast setting. So the first step is acknowledging the
Speaker 1: difference between weather and climate. This is important because I
Speaker 1: see these two concepts conflated all the time, and frequently
Speaker 1: it pops up in in political discussions because you have
Speaker 1: people with agendas who want to push specific action items
Speaker 1: that favor their philosophy over the action items of people
Speaker 1: who oppose their philosophy. And frequently in those discussions, people
Speaker 1: will start to make generalizations about weather and climate that are,
Speaker 1: if not untrue, at least inaccurate. So let's settle that.
Speaker 1: And I know all of you know this, but it's
Speaker 1: good to at least start with the baseline. So whether
Speaker 1: refers to the current state of the atmosphere, it's it's timely.
Speaker 1: It's either something that's happening right now, like you're talking
Speaker 1: about the weather right now, you're talking about a weather forecast.
Speaker 1: You're talking about something that's going to happen within the
Speaker 1: next day to ten days maybe or maybe a little
Speaker 1: further out, but that's about it. Or you're talking about
Speaker 1: what has happened over the past few days, but that's
Speaker 1: about it. Like it's about a month or so of
Speaker 1: time stretching backward and forward uh in total from where
Speaker 1: you are right now, So it's very timely. Climate, however,
Speaker 1: is about whether patterns over vast spans of time or
Speaker 1: at least several years, if not decades of time. So
Speaker 1: climate is more about general weather patterns and how they
Speaker 1: behave over these these uh the span of years. So
Speaker 1: climate change is very gradual. That means that you're not
Speaker 1: likely to notice climate change on a day to day basis,
Speaker 1: which means that if you use an argument like global
Speaker 1: warming isn't real because it's snowed last winter, that's a
Speaker 1: fallacious argument because you're talking there about whether not climate
Speaker 1: climate would be a gradual change, which over the course
Speaker 1: of several years might mean that after several years it's
Speaker 1: snowing less and less, or the snow is not lasting
Speaker 1: very long, the the period of time where it does
Speaker 1: snow is decreasing, like it's becoming more concentrated in a
Speaker 1: narrower span of days. Those are the sort of things
Speaker 1: we might see as a result of climate change over
Speaker 1: the course of several years. But we humans aren't very
Speaker 1: good at conceptualizing that. We tend to focus on stuff
Speaker 1: that we've recently observed, but particularly when it's something that's
Speaker 1: happening at at times. So if you were to have
Speaker 1: an unusually mild summer, you might think, well, that says
Speaker 1: that climate change is is bogus because I should it
Speaker 1: should be much hotter than that. That's not taking into
Speaker 1: account the long term changes in trends. So again, climate
Speaker 1: is the long view, whether is what is happening right now?
Speaker 1: Now that we've established that, we can get past those
Speaker 1: weird straw man arguments people make that tried to discredit
Speaker 1: one another for whatever philosophy they have using weather in
Speaker 1: place of climate, it just doesn't work. Climate change, by
Speaker 1: the way, is a real thing. Uh, it is a
Speaker 1: scientific consensus has found that climate change is real and
Speaker 1: that humans have had an impact, a significant impact on
Speaker 1: climate change. And consensus is no small matter getting scientists
Speaker 1: to agree to some thing. That's I mean, science is
Speaker 1: all about questioning claims and putting them to the test.
Speaker 1: That's how science works is you make an observation or
Speaker 1: you make a prediction, and then you test it over
Speaker 1: and over and over again to see if it holds true.
Speaker 1: If you get to a scientific consensus where a lot
Speaker 1: of scientists, the vast majority of them all agree on something,
Speaker 1: that's a powerful statement, although we often will see that dismissed.
Speaker 1: Uh So, again, this isn't to get political. This is
Speaker 1: just stating a scientific fact, not a political effect. Climate
Speaker 1: change is real, humans have an impact on it. What
Speaker 1: does that mean politically, Well, that's a totally different discussion.
Speaker 1: So there's probably people out there who wish that climate
Speaker 1: change wasn't a real thing, that this was all just
Speaker 1: a manufactured story. But if wishes were horses, beggars would ride.
Speaker 1: As my old social studies teacher would say, So, climate
Speaker 1: describes weather trends over many, many years, and weather describes
Speaker 1: changing atmospheric conditions on a much shorter time span. And
Speaker 1: our atmosphere is where weather happens. Again, not a big shock.
Speaker 1: This is elementary school science. It's made up of a
Speaker 1: lot of gases our atmosphere. The big one, of course,
Speaker 1: is nitrogen, that makes up about of the atmosphere. Then
Speaker 1: comes oxygen, which is my personal favorite. I'm totally breathless
Speaker 1: without oxygen. It makes up about of the art's atmosphere,
Speaker 1: and then you've got less than a percent of argone
Speaker 1: point zero three carbon dioxide, and the rest of it
Speaker 1: is made up of small amounts of water, vapor, hydrogen, ozone, neon, helium, crypton,
Speaker 1: and xenon. Our atmosphere is pretty thick, and there's not
Speaker 1: really a hard barrier between the top of the atmosphere
Speaker 1: in the beginning of space. It's kind of a fuzzy barrier,
Speaker 1: and there's not like you can't point to a specific
Speaker 1: height above the Earth and say, specifically, at this point
Speaker 1: the atmosphere ends, and this is just empty space beyond it.
Speaker 1: The best you can do is do an estimation. So
Speaker 1: generally speaking, the atmosphere pretty much peters out into nothing
Speaker 1: once you reach about six hundred miles or one thousand
Speaker 1: kilometers above sea level, So you gotta go at sea
Speaker 1: level six d miles up and you're pretty much at
Speaker 1: the point where you're not going to find any molecules
Speaker 1: of any significant number that represent an atmosphere. Gravity holds
Speaker 1: the gases down to the planet, which I'm sure seems
Speaker 1: pretty obvious. Without gravity, the atmosphere would dissipate into space,
Speaker 1: but don't worry, so would we. So the gases wouldn't
Speaker 1: be lonely for very long. It's a moot point because
Speaker 1: we do have gravity, so we're good. The atmosphere is
Speaker 1: also a very heavy thing. Collectively, if you take all
Speaker 1: of the other's atmosphere, it weighs five point five quadrillion uns.
Speaker 1: That's four point nine nine quadrillion metric tons. Again, that's collective.
Speaker 1: That's all the atmosphere that surrounds our planet. Obviously, you
Speaker 1: are not walking around with a few quadrillion tons of
Speaker 1: weight on top of you. This weight of the atmosphere
Speaker 1: creates atmospheric pressure. The pressure is different at various altitudes,
Speaker 1: which makes sense. If you are on top of a mountain,
Speaker 1: you actually have less atmosphere above you, like there's less
Speaker 1: air between you and outer space. If you're on top
Speaker 1: of a mountain, then if you were standing in the
Speaker 1: middle of a valley, there would be more air between
Speaker 1: you and outer space. Because again remember we're measuring that
Speaker 1: by sea level, so your altitude makes a big difference.
Speaker 1: You would have a lower atmospheric pressure at a high
Speaker 1: altitude than you would somewhere with a low altitude. The
Speaker 1: pressure also compresses the gases in the atmosphere, so air
Speaker 1: closer to the surface of the planet is more dense
Speaker 1: than air that's near the edges of space, and all
Speaker 1: the weight above that low altitude air is forcing the
Speaker 1: various molecules to get all chummy with each other. So
Speaker 1: you've got denser air closer to the surface. So I've
Speaker 1: got more to say about atmospheric pressure and it's rolling
Speaker 1: weather in just a minute. But before I jump into that,
Speaker 1: let me take a breath and thank our sponsor. All right,
Speaker 1: So let's say you are at sea level. The average
Speaker 1: atmospheric pressure at sea level is fourteen point seven pounds
Speaker 1: or six point seven kilograms per square inch. As you
Speaker 1: climb in altitude, the pressure and density of the air
Speaker 1: around you decreases until you reach a point where it
Speaker 1: would be quite difficult to breathe, and you need to
Speaker 1: breathe in more in order to get enough oxygen so
Speaker 1: that you can continue, you know, living. So you might
Speaker 1: take a lungfull and not get enough oxygen to remain
Speaker 1: conscious if you're at a high enough altitude, which is
Speaker 1: part of the reason why mountain climbers have to tackle
Speaker 1: really tall mountains and stages. They have to have camps
Speaker 1: where they take a break and acclimate to the lower
Speaker 1: air pressure and lower air density of higher altitudes. So
Speaker 1: gravity obviously plays a big part in weather systems keeping
Speaker 1: our atmosphere nice and in place. The Sun obviously also
Speaker 1: contributes to our weather patterns. The Sun is the direct
Speaker 1: source for most of the energy here on Earth. Some
Speaker 1: of the energy of the Sun gives off warms our
Speaker 1: atmosphere directly, but most atmospheric warming actually comes not from
Speaker 1: sunlight coming down to Earth, but rather the heat that
Speaker 1: is radiated off of Earth. The heat that the Earth
Speaker 1: has absorbed from the Sun. So the plant itself absorbs
Speaker 1: heat and then releases that heat later on. That tends
Speaker 1: to be what heats up most of the atmosphere. The
Speaker 1: reason this happens is because the type of radiation that
Speaker 1: we're talking about radiation from the Sun is short wave
Speaker 1: radiation that easily passes through the gases the atmosphere and
Speaker 1: then it gets absorbed by the planet. When the planet
Speaker 1: emits heat, it's emitting long wave radiation. Long wave radiation
Speaker 1: gets absorbed readily by the atmosphere, so the atmosphere warms
Speaker 1: from the ground up. And that also explains why if
Speaker 1: you were to climb a mountain as you would climb
Speaker 1: in elevation, the temperature would decrease to a point anyway
Speaker 1: in the troposphere. So there are four layers of Earth's atmosphere,
Speaker 1: and you classify those four layers by temperature ranges. The
Speaker 1: layers aren't uniform. Their thickness varies a bit as you
Speaker 1: go from region to region around the Earth, but they're
Speaker 1: roughly outer shells of Earth. The innermost one is the atmosphere,
Speaker 1: as the level closest to the surface of the Earth.
Speaker 1: It ends somewhere around seven miles or eleven kilometers above
Speaker 1: sea level on average. Throughout the troposphere, as you climb altitudes,
Speaker 1: the temperature drops. That's one of the markers for the
Speaker 1: troposphere that all stops when you pass the tropo pause.
Speaker 1: That is the boundary between the troposphere and the stratosphere.
Speaker 1: That is the next layer out from the troposphere. The
Speaker 1: tropospheres where all of Earth's weather happens. It also accounts
Speaker 1: for eighty percent of the air in our atmosphere. The
Speaker 1: other three layers contain the remaining twenty of the air
Speaker 1: in our atmosphere. Now, remember our atmosphere extends all the
Speaker 1: way up to six hundred miles above sea level, whereas
Speaker 1: the troposphere ends at seven miles above sea level. So
Speaker 1: within those first seven miles out of six hundred, you
Speaker 1: have eighty percent of the air in our atmosphere. That
Speaker 1: tells you how densely packed those gases are. The stratosphere
Speaker 1: extends from the tropopause up to about thirty miles above
Speaker 1: sea level or forty eight kilometers. For the first few miles,
Speaker 1: the temperature of the stratosphere remains pretty stable with regards
Speaker 1: to the tropopause below. So remember you climb up through
Speaker 1: the troposphere, the temperature starts to go down. When you
Speaker 1: hit the tropopause, the temperature pretty much stabilizes, and then
Speaker 1: you're in the stratosphere and the temperature remains stable for
Speaker 1: the first several miles, but then the temperatures actually start
Speaker 1: to increase. It starts to get warmer as you move
Speaker 1: through the stratosphere. This is because at those upper levels
Speaker 1: of the stratosphere you can find ozone. Ozone can absorb
Speaker 1: ultra violet radiation from the Sun. Unlike most of the
Speaker 1: other gases, it actually can absorb some of those short
Speaker 1: wave radiations. So the ozone heats up, which means the
Speaker 1: upper levels of the stratosphere are also warmer than the
Speaker 1: lower levels. Above the amosphere is the miso sphere, where
Speaker 1: temperatures decline again, getting to be the coldest temperatures in
Speaker 1: Earth's atmosphere. Those temperatures hovered around minus degrees fahrenheit or
Speaker 1: minus nineties celsius. And the final layer of the atmosphere
Speaker 1: is the thermosphere, which shares its outer body with space,
Speaker 1: and the air here is not dense at all. It's
Speaker 1: actually pretty widely spread out. The molecules are very thin like,
Speaker 1: it's very thinly populated, the opposite of very dense. In
Speaker 1: other words, the interesting thing here is that the thermosphere
Speaker 1: technically gets really freaking hot. We're talking like degrees fahrenheit
Speaker 1: or shundred degrees celsius. But because those molecules are so
Speaker 1: few and far between, it would not feel hot to
Speaker 1: you because you wouldn't be in contact with these highly
Speaker 1: energized molecules. They're spread too far apart from each other.
Speaker 1: It's kind of like being inside and an enormous arena
Speaker 1: stadium and there are a dozen ping pong balls flying around.
Speaker 1: The Odds of any of those ping pong balls actually
Speaker 1: making contact with you are pretty low. Because you're in
Speaker 1: a big area with these tiny things moving around, it's
Speaker 1: just not likely that you're gonna encounter one of them.
Speaker 1: Same thing is kind of true with molecules out in
Speaker 1: uh the the thermosphere. So while those molecules will be
Speaker 1: quite warm and you're not likely to run into them.
Speaker 1: Now back here on the surface, where we have the
Speaker 1: troposphere to deal with, you've got atmospheric pressure, you've got temperature.
Speaker 1: These two factors affect atmospheric movement. As gases heat up,
Speaker 1: the molecules in those gases move around more, they spread out,
Speaker 1: they become less dense. When the density changes enough so
Speaker 1: that the air above is more dense than the air below,
Speaker 1: that denser air is going to sink down and displace
Speaker 1: the warm air that is there. You might have heard
Speaker 1: the phrase warm air rises, Well, it's true, but it's
Speaker 1: really probably more accurate to say cold air sinks. If
Speaker 1: you were to have a very dense fluid and you
Speaker 1: put it on top of a less dense fluid, you'd
Speaker 1: see the dense fluids sink down to the bottom and
Speaker 1: the less dense fluid would rise to the top. Same
Speaker 1: thing is true with atmospheres and our atmosphere is a fluid,
Speaker 1: so these denser, colder areas sink down and that pushes
Speaker 1: the warm air up to the top. So this way
Speaker 1: you get some fluid movement in our atmosphere as different
Speaker 1: areas start to warm up or cool down. Now, as
Speaker 1: that warm air does rise, it actually starts to cool
Speaker 1: down because it's going up in altitude. And remember and
Speaker 1: those altitudes in the troposphere. The higher you go, the
Speaker 1: cooler it gets. So the warm air initially gets pushed
Speaker 1: up by colder air, but then the warm hair itself
Speaker 1: begins to cool and it has a tendency to sink again. Now,
Speaker 1: if everything we're equal, if our planet did not rotate,
Speaker 1: if we didn't have any uh variation in parts of
Speaker 1: the plant that warmed or cooled, if it all warmed
Speaker 1: or cooled at the same time, our atmosphere behavior would
Speaker 1: be really simple. It would expand when sun was hitting it,
Speaker 1: and it would contract when the sun wasn't hitting it.
Speaker 1: So you would just see the atmosphere kind of breathe
Speaker 1: that would move out and in based upon the warming
Speaker 1: and cooling, and that's all it would do. You wouldn't
Speaker 1: get a whole lot of other movement there, but that's
Speaker 1: not our reality. The reality is we have a lot
Speaker 1: of other factors at play that create the the conditions
Speaker 1: that allow wind to generate. So regions of the Earth
Speaker 1: warm at different rates at different speeds, and thus regions
Speaker 1: of our atmosphere end up warming at those different speeds,
Speaker 1: and that regional variation causes a lot of churning in
Speaker 1: the atmosphere, which creates pressure differentials between regions, thus leading
Speaker 1: to wind. So let's take a city and countryside example
Speaker 1: to kind of understand what I mean by this. If
Speaker 1: you have a city, the city heats up faster than
Speaker 1: the countryside would during the day due to a lot
Speaker 1: of the materials in the city, you know, concrete, blacktop,
Speaker 1: these sort of materials soak up a lot of heat,
Speaker 1: so they're going to get much warmer than the countryside wood,
Speaker 1: which doesn't have those sort of materials all through it.
Speaker 1: So you've probably heard of the island effect, which is
Speaker 1: where you get an island of heat because you've got
Speaker 1: a bunch of of mass that just absorbs heat readily
Speaker 1: in one space, and it creates an island effect within
Speaker 1: the region. That's what we're talking about here. The city
Speaker 1: ends up soaking up a lot of heat and then
Speaker 1: releases that heat. Over the course of many hours. As
Speaker 1: cities radiate heat, that heat warms the atmosphere that's surrounding
Speaker 1: the city's That warm air is less dense than the
Speaker 1: cold air that's further on the outskirts of the city,
Speaker 1: out in the countryside, So the warm air is an
Speaker 1: area of low pressure because it's less dense. It's actually
Speaker 1: exerting less pressure on the city because it weighs less.
Speaker 1: It is less dense than the cold air that's around it,
Speaker 1: or the relatively cold air compared to the city's air.
Speaker 1: So the cold air blows into the city because it
Speaker 1: wants to move from an area of high pressure to
Speaker 1: an area of low pressure, sort of that. In tropic movement,
Speaker 1: the warm air is forced upwards in an updraft and
Speaker 1: starts to climb up into the upper levels of the troposphere.
Speaker 1: As it does so, it starts to cool, and once
Speaker 1: it cools enough, it needs to come back down. But
Speaker 1: because cities soak up so much heat, and because the
Speaker 1: updraft can be so powerful, the cold air can't just
Speaker 1: sink back down to where it was. It actually has
Speaker 1: to move outward and then sink down further out from
Speaker 1: where the city is. It's almost like a fountain. You
Speaker 1: would see the water of the fountain come up in
Speaker 1: a column and then spread out in a fan the
Speaker 1: top and come back down to the base of the fountain.
Speaker 1: That's sort of what's happening, except with atmosphere, not with water,
Speaker 1: although it could be with water. We'll get into rain
Speaker 1: in just a second. So at night the city would
Speaker 1: cool faster than the countryside does, and then the trend
Speaker 1: would reverse itself. We would have winds that are originating
Speaker 1: essentially from the city moving out to the countryside. This
Speaker 1: little system is what we would call a convection cell,
Speaker 1: and convection is when the movement of mass or circulation
Speaker 1: of atmosphere transfers heat through some sort of substance. In
Speaker 1: this case, we're talking about the planet and the atmosphere.
Speaker 1: On a larger scale, forces affect these movements to generate
Speaker 1: massive weather weather patterns. The poles are areas of high
Speaker 1: pressure and the equator is an area of low pressure.
Speaker 1: You've got a lot warmer air moist air in the equator,
Speaker 1: a lot cold or dry air over at the poles.
Speaker 1: And if that was all there were to it, we
Speaker 1: would see winds coming from the north and south and
Speaker 1: converging towards the equator. But there are a lot of
Speaker 1: other areas of high and low pressure across the surface
Speaker 1: of the Earth. It's not just the polls and the equator.
Speaker 1: There's a lot of variation there due to tons of
Speaker 1: different stuff, including topography like mountains and valleys, that sort
Speaker 1: of thing, deserts. So you have lots of areas of
Speaker 1: high and low pressure across the surface of the Earth,
Speaker 1: which creates natural pressure gradients, and that generates wind. Wind
Speaker 1: from high pressure areas cycle inward to low pressure areas.
Speaker 1: In fact, we call a low pressure center a cyclone.
Speaker 1: Now it's not the same thing as cyclones that are
Speaker 1: also known as hurricanes, slightly different, although there is a
Speaker 1: circular motion to it. That's where you get that cyclone
Speaker 1: name there. High pressure centers are anti cyclones, as an
Speaker 1: anti not as an anti cyclone the sister of my father,
Speaker 1: who we don't talk about. It's a different thing entirely.
Speaker 1: High pressure air moves in a down undraft as low
Speaker 1: pressure air moves in an updraft, and Earth's rotation also
Speaker 1: gets into the game. This is where we get the
Speaker 1: Coriolis effect. In the northern hemisphere, wind deflects towards the right.
Speaker 1: In the southern hemisphere it's deflected to the left. The
Speaker 1: Coriolis effect really influences large fluid masses, by the way,
Speaker 1: so it does not necessarily affect which way the water
Speaker 1: goes down a sink or a toilet, despite what the
Speaker 1: Simpsons would have you believe. Uh, there are a lot
Speaker 1: of other smaller things that can affect the way water
Speaker 1: drains down the drain and is not the Coriolis effect.
Speaker 1: Coriolis effect is really for very big systems, not for
Speaker 1: small systems like a a sink full of water or
Speaker 1: a tub full of water. But the Coriolis effect does
Speaker 1: break the two big convection cells that otherwise would exist,
Speaker 1: you know, the ones that would be the North and
Speaker 1: South hemispheres, and it ends up creating three different types
Speaker 1: of convection cells. You get two of each type. You
Speaker 1: have two polar cells to Hadley cells, and two Feral cells.
Speaker 1: And the Hadley and Feral cells are named after meteorologists
Speaker 1: who discovered them. This is the important thing, really is
Speaker 1: to remember that these convection cells have a really big
Speaker 1: impact on on larger weather trends, global weather trends now
Speaker 1: where the wind blows down here near the surface, air
Speaker 1: encounters resistance in the form of friction, but a bit
Speaker 1: higher up in the atmosphere that's not a problem. So
Speaker 1: jet streams shoot around at fairly high altitudes we're talking
Speaker 1: twenty thoty five thou feet or between six and fourteen kilometers,
Speaker 1: and they don't encounter this friction. They move it incredible speeds.
Speaker 1: They can carry temperature changes effectively around the world. So
Speaker 1: you'll see things about jet stream and how that will
Speaker 1: affect local weather patterns depending upon where you live. High
Speaker 1: altitude winds, the coreolas, affected pressure gradients are the three
Speaker 1: big influencers of wind generation on a global scale. But
Speaker 1: remember regional geography, coastlines, mountains, valleys, all of that also
Speaker 1: has an effect. Regional heating and cooling has an effect.
Speaker 1: So these big factors are the major variables, but they're
Speaker 1: not the only ones. And now you're starting to see
Speaker 1: all the complications that come into just describing weather, let
Speaker 1: alone predicting it. But that covers wind. Rain is pretty
Speaker 1: easy to explain. The water cycle on Earth is pretty
Speaker 1: much a closed system. Water evaporates into the atmosphere. Water
Speaker 1: vapor condenses as it cools down, so it condenses from
Speaker 1: water vapor and turns into liquid water. It starts to
Speaker 1: cling to specs of stuff in the atmosphere, little particles
Speaker 1: of dust. Uh. That ends up becoming the nucleic sites
Speaker 1: for rain drops. If it is able to accumulate enough
Speaker 1: water vapor. The cooling happens. Once water vapor rises high
Speaker 1: enough into the air, and with enough cooling water vapor,
Speaker 1: you get clouds. Wind will push and reshape the clouds,
Speaker 1: moving them to different locations. And if you get enough
Speaker 1: water vapor condensing around those nucleic sites, it becomes too
Speaker 1: heavy to remain aloft by the winds alone, and it
Speaker 1: starts to fall. And that's when you get rain, or
Speaker 1: if it's really cold, you might get sleet or freezing
Speaker 1: rain or snow. But you get what I mean, you
Speaker 1: get precipitation. I've got a little bit more to say
Speaker 1: about the water cycle and other elements of weather, but
Speaker 1: before I jump into that, let's take another quick break
Speaker 1: and thank our sponsor. So water vapor can be pushed
Speaker 1: into higher altitudes through several different ways. One of those
Speaker 1: is just changes in elevation in the land. So if
Speaker 1: you have a warm air system and it's got a
Speaker 1: lot of water vapor in it, and it moves across
Speaker 1: flat lands and start to encounter mountains, it has to
Speaker 1: conform with the topography, so as it gets pushed against
Speaker 1: the mountain, it actually starts to go up the mountain,
Speaker 1: and that means some of that water vapor gets pushed
Speaker 1: up to higher elevations and it gets high enough, then
Speaker 1: it can cool down, condense, turn into clouds, and eventually
Speaker 1: even turn into precipitation. So if you've ever heard about
Speaker 1: windward and leeward that's what this refers to. The windward
Speaker 1: side of a mountain is the side that faces the
Speaker 1: area where wind comes in from. So traditionally the direction
Speaker 1: front which fronts move through, so you have a warm
Speaker 1: air mass coming through to a hit a mountain, that's
Speaker 1: the windward side. The leeward side tends to be gloomy
Speaker 1: and covered in rain a lot because that water vapor
Speaker 1: that hits the windward side gets forced upwards into the
Speaker 1: higher parts of the atmosphere or of the troposphere i
Speaker 1: should say, condenses into uh into clouds, and then eventually
Speaker 1: can turn into rain or precipitation of other forms, and
Speaker 1: on the leeward side that's where you get that rain,
Speaker 1: and you also have a lot of cloud cover. So
Speaker 1: there's a sunny side of a mountain and there's the
Speaker 1: less sunny side of the mountain. Typically, and uh, that's
Speaker 1: one way water vapora can be pushed into high altitudes
Speaker 1: to form clouds. But there's also an way called frontal wedging,
Speaker 1: which originally I thought was something that happened to me
Speaker 1: back in middle school, but it turns out I was
Speaker 1: thinking of something totally different. This is actually when warm
Speaker 1: air ends up colliding with a cold air mass, and
Speaker 1: the cold air mass sort sort of acts like a
Speaker 1: ramp because remember a cold air is more dense than
Speaker 1: warm air, so warm air is going to float above
Speaker 1: or rise over cold air. It ends up being wedged
Speaker 1: on top of cold air. That pushes warm water vapor
Speaker 1: up into those higher altitudes again where it can condense
Speaker 1: and form clouds. So if you have a warm air
Speaker 1: mass moving into to a cold front, or rather a
Speaker 1: cold air mass, not a cold front, then this can happen.
Speaker 1: The warm air will rise over the cold air, the
Speaker 1: water vapor in the warm air will slowly condense and
Speaker 1: then you end up getting clouds as a result. This
Speaker 1: is typically what we call a front. So a warm
Speaker 1: front is when warm air moves into an area that
Speaker 1: has cold air in it. A cold front is when
Speaker 1: cold air moves into an area that has warm air
Speaker 1: into it. So essentially it's a low pressure system moving
Speaker 1: into a high pressure system, or a high pressure system
Speaker 1: moving into a low pressure system. And then you've got
Speaker 1: these masses colliding with one another. Really, it just depends
Speaker 1: on what type of air mass is moving in and
Speaker 1: what type of air mass is currently in the region.
Speaker 1: That determines whether it's a cold front or a warm front.
Speaker 1: But then you also have two other types of fronts.
Speaker 1: You have a stationary front, and these cases you have
Speaker 1: two air masses that are unable to advance against each other.
Speaker 1: They kind of just bump up against each other and
Speaker 1: stay there. And then you have the occluded front. This
Speaker 1: is when a cold front moves fast enough to overtake
Speaker 1: a moving warm front. So that's another way that water
Speaker 1: vapor can be pushed up into the higher elevations. Way
Speaker 1: number three for water vapor to go moved moving up
Speaker 1: to those higher altitudes is called convergence. Now this is
Speaker 1: not the same type of convergence I typically like to
Speaker 1: talk about here on tech stuff. It's when two similar
Speaker 1: air masses collide and both end up forcing air into
Speaker 1: an updraft, which includes water vapor. And so yet again
Speaker 1: we see water vapor get pushed up and cooling down
Speaker 1: to condense. But that's convergence. And finally you have what
Speaker 1: is called convective lifting. This is a localized effect, so
Speaker 1: it's not something that happens on regional or global scales,
Speaker 1: but rather very local scales. It's when Earth's radiation of
Speaker 1: heat causes a pocket of air to warm and rise,
Speaker 1: forcing water vapor up in the process and creating clouds.
Speaker 1: This requires having an area that is absorbing a lot
Speaker 1: more heat than its surroundings typically do. So a good
Speaker 1: example might be a large airport. The airport's got a
Speaker 1: lot of surface area that gets exposure to the sun.
Speaker 1: It absorbs a lot of heat, much more heat than
Speaker 1: the surrounding area typically does, and so it releases more
Speaker 1: heat and as a result, you can get cloud formation
Speaker 1: above airports just because of this localized convective lifting. So
Speaker 1: now we understand the general principles behind weather that air
Speaker 1: pressure temperature and the presence of water vapor matter a lot.
Speaker 1: Now other things matter too, of course. The Earth's access,
Speaker 1: for example, is that twenty three and a half degrees tilt,
Speaker 1: which means we're likely, uh, we're we're we're like, we're bobbling,
Speaker 1: bobbling around like a wobbly top as we orbit the Sun,
Speaker 1: and this causes different parts of the planet to receive
Speaker 1: more or less sun exposure during certain parts of the year.
Speaker 1: That ends up affecting weather patterns and seasonal patterns and weather.
Speaker 1: It's complicated in that incoming systems can have a dramatic
Speaker 1: effect on systems that are already within a region. So
Speaker 1: it's an enormous, chaotic mess with lots of variables, and
Speaker 1: that's part of the reason why meteorology is so darned challenging.
Speaker 1: We cannot isolate those variables. We cannot really understand how
Speaker 1: to properly weight all of them in every situation. That is,
Speaker 1: determining which variables are most important under any given set
Speaker 1: of circumstances, it's really really hard to do. So you
Speaker 1: might say that under a certain set of conditions, the
Speaker 1: temperature of the air is the most important variable, and
Speaker 1: that depending upon that temperature of the air, certain outcomes
Speaker 1: are almost absolutely gonna happen, right But then you might say,
Speaker 1: under slightly different circumstances, temperature no longer becomes the most
Speaker 1: important variable. Now it's air pressure that's more important than temperature.
Speaker 1: Weather is so complicated, and there's so many different variables
Speaker 1: that have different weights and different situations that it becomes very,
Speaker 1: very difficult to understand what is happening right now, let
Speaker 1: alone predicting what is going to happen. In fact, I
Speaker 1: find it amazing that we can manage to have any
Speaker 1: real accuracy and weather predictions at all, because it's so
Speaker 1: crazy complicated. Now, Before I wrap up, I thought it'd
Speaker 1: be fun to talk about some of the earlier forms
Speaker 1: of weather forecasting before you know, sensors and and observing
Speaker 1: stations and computer models came along. The stuff we used
Speaker 1: to do before we had all those sophisticated technologies and
Speaker 1: really a truly astonishing amount of processing power capable of
Speaker 1: handling all those points of data simultaneously. Because we humans
Speaker 1: have been trying to suss out weather for centuries, knowing
Speaker 1: what the weather will be like has a tremendous impact
Speaker 1: on our decisions like should I buy tickets to that
Speaker 1: outdoor sporting event, or how can I plot a course
Speaker 1: for these shipping goods to get from point A to
Speaker 1: point B with the least amount of delay and fuel consumption.
Speaker 1: But our methods for making predictions haven't always been terribly scientific,
Speaker 1: and it's heart a lot of our weather predictions were
Speaker 1: centered on pattern recognition. That's what I alluded to at
Speaker 1: the top of this episode. We would say, hey, remember
Speaker 1: that other day that was a lot like today. Well,
Speaker 1: it rained like a son of a gun later on
Speaker 1: the evening, and that other day, I bet that happens
Speaker 1: again tonight. I bet we get more rain tonight, because
Speaker 1: that's what happened that other day. Early human civilizations made
Speaker 1: similar observations and predictions, which range from the immediate, which
Speaker 1: would involve something like I better seek shelter because it
Speaker 1: looks like it's going to storm, to more long term planning,
Speaker 1: such as I've noticed that the weather seems to get
Speaker 1: warmer for a while, and then everything is growing, and
Speaker 1: then after a while the weather starts getting cold and
Speaker 1: everything stops growing. So maybe I should grow stuff in
Speaker 1: this one part of time and harvest stuff at this
Speaker 1: other part of time. In other words, we started learning
Speaker 1: more about how seasons work. There are some changes in
Speaker 1: conditions that are a bit too subtle for humans to
Speaker 1: pick up on them by themselves, but they're are other
Speaker 1: animals that are more sensitive to those changes, things like
Speaker 1: atmospheric pressure, for example, and so humans would sometimes observe
Speaker 1: changes in animal behavior that would precede certain types of
Speaker 1: weather events. Those behaviors would become associated with weather, leading
Speaker 1: to some folk knowledge about what it means when your cow,
Speaker 1: I don't know, switches from Xbox to PlayStation. I guess
Speaker 1: I should point out right now that I haven't been
Speaker 1: on a farm in like thirty years, so my understanding
Speaker 1: of animal behavior might be a little off. But those
Speaker 1: approaches don't really give you very much detail, nor are
Speaker 1: they useful outside of the immediate area. If you see
Speaker 1: your cows are playing Halo two instead of Uncharted, it
Speaker 1: doesn't tell you about the weather that's going on in
Speaker 1: the town on the other side of the valley, for example.
Speaker 1: And let's say that you want to go to the
Speaker 1: other side of the valley because you need to sell
Speaker 1: your I don't know yearly parsnip harvest, So for that
Speaker 1: you would need more information. You would need someone on
Speaker 1: the other side of the valley sending you observations of
Speaker 1: their weather phenomena, and also a way of understanding what
Speaker 1: those observations mean in relation to that area's local weather.
Speaker 1: You would need a meteorologist and some reliable data gathering sensors,
Speaker 1: and in our next episode will explore those worlds and
Speaker 1: talk about the complex models scientists have created to describe
Speaker 1: and predict our weather and to really get a grip
Speaker 1: on how impressive it is and why we need supercomputers
Speaker 1: to run some of these weather models. Will also talk
Speaker 1: about why are there more than one? Why is there
Speaker 1: more than one weather model? Wouldn't one weather model work
Speaker 1: for everywhere? As it turns out new there are a
Speaker 1: lot of different weather models, and they all have different
Speaker 1: levels of resolution, meaning some of them have way more
Speaker 1: observing stations reporting in for a localized area, which means
Speaker 1: you have very very accurate reports of what is happening
Speaker 1: in a specific region, but they don't cover a large region,
Speaker 1: like a large area might be a section of a country,
Speaker 1: but not an entire country, or certainly not a continent.
Speaker 1: Then you might have much larger weather models that cover continents,
Speaker 1: but they do so at a much lower resolution. You
Speaker 1: don't have specific accuracy for independent regions. Ideally, what we
Speaker 1: want to arrive at is a global model that can
Speaker 1: have incredible resolution down to the local level, so that
Speaker 1: we know what the weather is going to be like
Speaker 1: in our hometown, we know what the weather is going
Speaker 1: to be like in the place we're going to travel
Speaker 1: to on the other side of the world, and we
Speaker 1: can even see how the weather conditions in one location
Speaker 1: are affecting the subsequent locations further down the line. That's ideal.
Speaker 1: We are not there yet in our next episode. We'll
Speaker 1: talk about why that is. But for now, if you
Speaker 1: guys have suggestions for future episodes of tech Stuff, please
Speaker 1: let me know what those are, because I hate guessing.
Speaker 1: You can write me My address is tech stuff at
Speaker 1: how stuff works dot com, or you can drop me
Speaker 1: a line on Facebook or Twitter to handle at both
Speaker 1: of those is tech Stuff hs W. If you would
Speaker 1: like to watch me record an episode live, go to
Speaker 1: twitch dot tv slash tech stuff. You can see the
Speaker 1: schedule there and you can join in and watch as
Speaker 1: we have technical difficulties that extend a forty five minute
Speaker 1: long recording session into an hour and a half that
Speaker 1: really happened today, and you wouldn't be able to see
Speaker 1: it unless you go to Twitch dot tv slash tech
Speaker 1: stuff to enjoy and watch as other people pop into
Speaker 1: the studio and try and fix problems. It's exciting. I
Speaker 1: hope to see you there and I'll talk to you
Speaker 1: again really soon for more on this and thousands of
Speaker 1: other topics. Because it has staff works dot com