Hi. It’s Mr. Andersen. And this is environmental science video 4. It is on the atmosphere, which is the gas
covering on our planet. Remember we live in the atmosphere and as
society gets larger we are pushing against these planetary boundaries. And since the economy is pushing us towards
that the economy is going to have to bring us back. A story that relates to this is the story
of stratospheric ozone. We call that good ozone. It is made of three oxygen atoms. And it surrounds the planet. And it protects us from harmful UV radiation. But in the 1960s and 1970s we were producing
huge amount of CFCs. The CFC, this is an example, it is a carbon
fluorine, 3 chlorine molecules. It would also go into the atmosphere, get
hit by UV radiation, kicks off a chlorine, binds to an oxygen atom, and now we have destroyed
the ozone. And so you probably heard of this hole in
the ozone. This one is right here over Antartica. What is going to happen if we do not have
that protective ozone, increase in cancer, damage to crops. And so this is a really big deal. And so how do we solve that problem? Industry is going to say, rightly so, we should
not have to bare the cost of all of this. It is going to cost us, you know, millions
if not billions of dollars. We are going to lose jobs. But eventually the consensus came around and
governments said we are going to have to solve this problem. And in 1987 they signed on to what is called
the Montreal Protocol, where they banned CFCs. That has lead to a decrease in CFCs, increase
now of ozone. It will probably return to its original levels
2050. And so this is a great example of how governments
can find together like form a treaty that is incredibly successful. And so the atmosphere surrounds the earth. Scientists break it into a number of different
spheres. We have the tropo, stato, meso, thermo and
exo sphere. Now we live in the troposphere and that protective
ozone is going to be found right at this boundary between the two. Weather is going to be the current state of
our atmosphere. And over a long period of time we call that
climate, which is due to the tilt of our axis and where we are in the orbit around the sun. And so due to our location we get seasons. We are pointed towards the sun in the summer
and away from the sun in the winter. But also since we are sphere we are starting
to get unequal heating of the planet. And those convection currents lead to cells
in the atmosphere. We have things like the hadley cell, the ferrel
cell. And what those are doing is moving the atmosphere
around on our planet. Now we also have a spinning planet and that
creates something call the coriolis effect. And so it spins in a characteristic way. And so the combination of these two lead to
atmospheric circulation. It is moving the weather around on our planet. Now the oceans also affect our climate. And as the atmosphere moves around it starts
to move the oceans. And so we get these ocean currents, which
are shaping our climate. And an example of all of these things coming
together in el Nino or Enso, the el Nino oscillation which we will talk about in a little bit. And so the atmosphere is a series of spheres
that surround our planet. This is not to scale but the lowest one is
going to be the troposphere. That is where our mountains are. That is where we are. When you are on a jet you are still within
the troposphere. About that we are going to have the stratosphere. So weather balloons will move into that area. If we look at ozone right, so this is going
to be ozone right at the surface of the planet, we are going to have some bad ozone. We call that tropospheric or smog ozone that
can be damaging to us. We will talk about that later. But as we move up in the troposphere into
the stratosphere we are going to have a huge increase in that ozone layer. That is that protective layer around us. Above the stratosphere we have the mesosphere. That is where meteors are burning up. Above that we have the aurora are. That is going to be the thermosphere. And then finally we are bordering space. This is going to be the exosphere up here. Now what are some conditions within the whole
atmosphere? We are going to increase density the closer
we get to the earth because there is higher gravitational pull the closer we are. Now what is the atmosphere like today. That is weather. Is it raining? Is it sunny? What is the temperature? And that is important. But what is more important is climate. That is going to be weather over a long period
of time. And if we look at this biomap you start to
see some patterns. And so if you can look right here we are going
to have a bunch of tropical rainforest. We will have deserts right here. And if I put the latitudes over this, the
one thing that I am always surprised is how low the equator is. So if we put this in at 0 degrees, then 30
and then 60, real patterns start to emerge. So right here along the equator we going to
have all of this precipitation. Rainforests are going to be found there. But look right here at 30 degrees, above and
below, or northern and southern, we are going to have these deserts. And then we are going to have these big boreal
forests out here. And so all of that has to do with where the
earth is in orbit and also the tilt of the earth. And so we get seasons due to the tilt of the
earth as it moves around the sun. This is obviously not to scale, but as the
northern hemisphere is pointed toward the sun, look here on the north pole, it is going
to be 24 hours of daylight. In the winter it is going to be 24 hours of
night. Right here we would have the equinoxes. But depending on are we pointed towards the
sun, summer or away from the sun, winter, it is going to affect our weather and therefore
our climate. Remember everything would be reversed if we
were in the southern hemisphere. We also get unequal heating. So if I, again not to scale, but if I were
to put an atmosphere in here, as the suns rays come in here at this part it is going
through a very small amount of the atmosphere. So we do not lose much heat. But up here we are going to through more of
the atmosphere. It is going to be colder near the top. If we remove that and just look at the light
itself, right here this amount of sun rays is all concentrated on this very small surface
area. But up here near the north pole it is spread
out over a long surface area, a large surface area. So it is going to be cooler near the poles. Now remember as we move around the sun that
axis is going to tilt back and forth and so that is going to affect us on a equal heating. And the last thing that affects unequal heating
is the albedo of the earth. It is our reflectiveness. So as the sunlight hits the snow, for example,
it is going to be reflected off. But if it hits vegetation or water for example,
we are going to have a different amount of albedo. So it is a combination of all of these things
that creates climate. First one that is most important are going
to be the cells on our planet. What that means is right here at the equator
we are heating up the air, most right here along this point and so what we get are these
convection cells. So we heat up the air and it is moving up. It becomes less dense and it is moving up. Now what quickly happens to it is it actually
cools down. And so as it cools down we eventually reach
something called the dew point. That is where it cannot hold water anymore
and we are going to have the formation of clouds. And then we are going to have precipitation. Have you ever wondered why the bottoms of
all of the clouds line up? It is because we are cooling the air as it
moves up until we hit that due point. Now what happens eventually is that that atmosphere
is going to start to drop down again. And so we have another cell here and another
cell here. So if we were to look at the equator we are
going to have a huge amount of precipitation here, but remember at around 30 degrees all
of that air is moving down, it actually is being heated up and we are not going to have
much precipitation there. Or at the pole itself. And so these will be affected by the tilt
of the earth as well. And so cells are important to understand,
so I have turned the earth on its side. So this is now equator, north pole. So if we move from the equator to the north
pole the first thing we see is a huge amount of convection near the equator and you are
going to have a huge amount of weather right here. It will eventually move up and then it slides
down. As it moves down it is going to actually heat
up and we are not going to have much precipitation at 30 degrees. We call this first one the hadley cell. It is named in honor of the person who proposed
it. Now if we keep moving, so again we are moving
down to this next cell right here, we are also going to have convection current that
is moving the air up at 60 degrees north latitude and south. And then eventually it is going to be heated
as it moves down. So we are going to have more precipitation
here. We call this the ferrel cell. It is named in honor of the person who proposed
it. And then finally we have a polar cell. It is named in honor of . . ., no its not. It is just near the pole. And so the other things that contributes to
atmospheric circulation is coriolis effect. So again the earth is spinning. Think of it like a record player spinning
around. If I were to tape something to the record
player, like this cone, let’s say it represents then mountains, as the record player spins
the mountains are just going to move around with the earth. We are moving on the earth right now. We are not affected by it because we are connected
to the earth. But let’s say I put something on that record
player that is movable. Let’s say I put a marble on it and now I
spin it. Watch what happens to the marble. It will be deflected off. And if I were to trace that path it moves
like this. And so if you think about it, on the north
side of the record it is going to be moving clockwise. But if you could move underneath the record
it would actually be moving counter-clockwise. And so the earth is like that record player. It is a sphere, obviously, but in the northern
hemisphere it is going to move clockwise. In the southern hemisphere it is going to
move counter-clockwise. And so the combination of these cells and
coriolis effect creates the weather patterns that we have on our planet. So you can see here are the three cells, hadley,
ferrel and polar cells right here. But we also have the movement due to the spin
of the earth. And so right here near the equator we are
going to have what are called the trade winds. They are always going to be moving in this
direction due to the spin of the earth. Both in the southern and northern hemisphere
they are all moving in this direction. If we move north or south we are going to
start to get what are called the westerly, because it is going to be moving in this direction. Now as that atmosphere pushes on the ocean,
we get oceanic currents. We are getting these trade winds and then
we are getting the westerlies coming back. As that blows on the ocean we get this gulf
stream that is moving the ocean. We also start to get deep currents in the
ocean due to heat but also due to changes in salinity. And so this ocean is moving around, as a consequence
of not only salt but also the temperature. And so tying this all together is something
you should be very familiar with is Enso or the en nino southern oscillation. And what really is going on is it is just
moving back and forth between el nino and la nina. And so this is a graph that shows this oscillation
from 1880 to 2010. And so it is in a neutral position, it will
then move towards el nino. And then it will move back to la nina. And then it will move to el nino. Sometimes it is not a very big el nino. Sometimes it is a very big el nino or la nina. It just moves back and forth. So it is oscillating. You can see that in their record. But you should be asking yourself, what causes
it? And so let’s go look. So here we are looking at the Pacific Ocean. So this is the Pacific Ocean right here. This would be Central America, South America,
North America and then all the way on the other side of the Pacific is going to be Australia
over here. And so what we have is a walker circulation. Remember the trade winds are blowing the wind
in this direction along the equator. And as they do that what we get is a circulation
pattern that moves the ocean water, cold water here, it is pushing the warm water to the
western Pacific. This is the neutral or the normal position. Now what can happen, watch what happens to
the walker circulation as I move us into a la nina. So as I move us into la nina watch what happens
to the walker circulation. We have greater trade winds, an increase in
trade winds is pushing more of that warm water over here towards Australia. So we are going to get that weather way over
here. It is going to be cooler here around Central
America. Now watch what happens when the walker circulation
starts to die off, now we have el nino. And so we do not have that huge push and so
we are going to have warm weather, it actually starts to move in the opposite direction. And so this ocean is now going to affect the
atmosphere and it is going to affect humanity as well. So could you fill in this concept map? I would encourage you to pause the video and
give it a try. And then I will tell you the answers. First thing, could you tell me the levels
inside the atmosphere? It is troposphere, stratosphere, mesosphere,
thermosphere, so that should be here and exosphere. My mnemonic for this is try some milk then
eggs. That is a good way to remember the layers. Right here we would have the important ozone
gas which can be bad if we have it way down here in the troposphere. Weather over a long period of time is going
to be the climate, which is affected by the tilt of the earth and the sun and the location
of the sun. So we get seasons from that. We also get unequal heating which creates
these convection cells. Hadley cell, ferrel cell, polar cell. The spin of the earth creates the coriolis
effect and also the ocean can impact that. So hopefully you got all of those right. And I hope that was helpful.
