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He explains how stratospheric ozone is formed when diatomic oxygen absorbs an ultraviolet photon and is split into two free oxygen atoms. The free atoms bond with another oxygen molecule to form an ozone molecule creating a stable ozone layer. He then explains how chlorine atoms released from chlorofluorocarbon molecules act as an enzyme to breakdown up to 100,000 ozone molecules. The Montreal Protocol was a treaty signed by countries on the planet to reduce the amount of CFCs in the atmosphere to protect the ozone layer.
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Transcript Provided by YouTube:
00:03
hi it’s mr. Andersen and this is AP
00:06
environmental sciences video 33 it’s on
00:08
stratospheric ozone or good ozone we
00:10
call it good because it protects us
00:12
against ultraviolet radiation this
00:14
person’s skin doesn’t look like it has
00:15
much damage but if we look at it with UV
00:17
radiation you start to see blemishes
00:19
freckles pop out right away and if you
00:22
were to take a picture of my face or
00:23
somebody who’s much older than me
00:24
there’s going to be more damage due to
00:26
ultraviolet radiation so we should wear
00:28
sunscreen
00:29
what sunscreen does you can see it on
00:30
the left side of this person’s face is
00:32
absorb that ultraviolet radiation
00:34
protects us from the ravages of
00:36
ultraviolet radiation thankfully our
00:38
planet is wrapped in sunscreen it’s
00:41
wrapped in this ozone layer protects us
00:43
especially from UVC radiation why is
00:46
that important well until we had an
00:48
ozone layer on our planet until we had
00:49
an appreciable atmosphere life couldn’t
00:51
exist on land all life had to be in the
00:53
oceans but once we had the ozone layer
00:56
protected us
00:57
the problem is with industrialization we
00:59
started to produce chemicals like CFCs
01:01
they release chlorine into the
01:03
atmosphere and what they do is they
01:04
destroy ozone so this is a simulation of
01:07
what would have happened if we didn’t
01:09
stop using these CFCs over time this is
01:12
a NASA prediction so you can see here on
01:14
the bottom that over time by 2020 by
01:17
2040 by the time we get to 2060
01:19
essentially all of that ozone is gone
01:22
all of that protection is gone as well
01:24
and so ozone is simply oxygen instead of
01:27
being oxygen diatomic oxygen two atoms
01:30
of oxygen it’s actually three atoms of
01:33
oxygen connected together it’s found in
01:36
two layers in our atmosphere in the
01:37
troposphere we call that the bad ozone
01:39
because it leads to pollution smog for
01:42
example is produce through ozone but
01:44
what I’m talking about is the good ozone
01:46
the stratospheric ozone that forms the
01:48
ozone layer that protects us on this
01:50
planet protects us from ultraviolet
01:52
radiation now some of that gets through
01:54
that ultraviolet radiation is ordered
01:57
from A to B to C in ascending energy and
02:00
also descending wavelength the UVA
02:03
radiation moves right through the ozone
02:05
layer but this is not too damaging if
02:08
you’ve ever looked at a black light
02:09
that’s UVA radio
02:11
most of the UVB is filtered out and all
02:13
of the UVC the most damaging type of
02:16
ultraviolet radiation is filtered out by
02:18
the stratospheric ozone the nice thing
02:21
about that UVC radiation is that when
02:23
it’s hit regular oxygen forms ozone
02:27
which can then be broken down again so
02:28
we have this nice feedback cycle as long
02:30
as the sun is shining as long as we have
02:33
ultraviolet radiation we’re producing
02:35
ozone to protect us the problem is we
02:37
started producing chemicals like
02:39
chlorofluorocarbons which released
02:41
chlorine into the atmosphere and what it
02:43
does is acts as an enzyme to break down
02:45
that ozone and so we had the hole in the
02:47
ozone layer you’re probably familiar
02:48
with that it would have gotten larger if
02:50
we didn’t do something to stop it and so
02:53
1989 the Montreal Protocol was put
02:55
forward as a way to limit CFCs in our on
02:58
our planet so if we look at the amounts
03:00
of ozone on this graph this is going to
03:02
be right near the surface of the earth
03:03
we’re going to have large amounts near
03:05
the surface and it’s going to drop off
03:07
and then we’re going to have large
03:08
amounts as we go you know kilometers
03:10
away from the surface this near the
03:12
bottom is called tropospheric ozone this
03:14
is that bad ozone it can create smog
03:17
also leads to lung irritation can lead
03:19
to things like lung cancer as we move
03:22
farther and farther up we get into the
03:23
stratospheric ozone that’s the ozone
03:25
we’re talking about this is the ozone
03:26
layer large amounts of ozone high in the
03:29
atmosphere it’s this oh three molecule
03:32
it doesn’t start as an oh three molecule
03:34
we basically have a bunch of regular
03:36
oxygen diatomic oxygen it’s hit by
03:38
ultraviolet radiation and it breaks it
03:41
apart into two atoms of oxygen this free
03:43
atom of oxygen bonds to diatomic oxygen
03:46
and now we’ve got our ozone that’s how
03:48
it’s formed we need the radiation to
03:50
form the ozone it’s also out it breaks
03:52
down so if it’s hit by another bit of UV
03:54
radiation then it breaks that again and
03:56
now we’re doing this cycle we’re doing
03:58
the cycle of solar formation when we
04:00
take regular oxygen hit it with a photon
04:02
break it into these free atoms which
04:05
then bond to another oxygen atom to make
04:07
ozone and then we have solar breakdown
04:09
that’s when we have the ozone it’s hit
04:11
with a photon we break it down and then
04:13
we make that good old-fashioned oxygen
04:15
again and so it’s a nice cycle as long
04:17
as the sun is shining we’re going to
04:19
have ozone and the importance of ozone
04:21
is protection so if we look at the
04:23
amount of UV radiation at move
04:24
right through those layers in our
04:26
atmosphere you be UVB is mostly filtered
04:29
out and UVC is completely filtered out
04:31
and you might think why is that well it
04:33
has to do with the wavelength of that
04:36
radiation thankfully the radiations
04:39
wavelength fits that oxygen bond it’s
04:42
able to break it apart and it’s able to
04:43
make that ozone now the problem is we
04:45
started producing things like
04:47
chlorofluorocarbons what is a
04:48
chlorofluorocarbon if we just break down
04:50
the word it’s three chlorine atoms so
04:53
that’s the chloro part we then have the
04:55
fluoro part so it’s one fluorine atom
04:57
and then we have a carbon atom and what
04:59
happens when chlorofluorocarbons are hit
05:01
by radiation is it breaks off a chlorine
05:04
atom now watch what happens to that
05:06
chlorine atom it grabbed one of the
05:08
atoms from an ozone so if we look at the
05:10
atmosphere we’ve got a lot of ozone at
05:12
this point but now that we’ve freed up
05:14
that chlorine it grabs another one it
05:16
grabs another one it grabs another one
05:19
and so what it’s doing is it’s breaking
05:20
down all that ozone it’s acting as an
05:22
enzyme it’s not consumed in the reaction
05:25
it simply breaks down the ozone and one
05:28
chlorine atom can break down a
05:29
hundred-thousand zone atoms and so it
05:32
goes really really quickly and that led
05:34
to the ozone hole now why is that
05:35
ozone hole found on the pole remember
05:37
there’s going to be an area where we’re
05:39
not having a lot of light there’s not a
05:41
lot of radiation so we can’t build that
05:43
ozone back up and so we started to see
05:44
it here first but it would have spread
05:46
across the whole planet and so what
05:48
humans did is they got together and they
05:50
formed the Montreal Protocol to treaty
05:53
that all of these countries were signing
05:54
and they said we have to stop using
05:56
these CFCs and so if you look at where
05:59
we were headed with the amount of CFCs
06:01
we were producing things in freon for
06:04
example aerosols for example we were
06:06
leading to destruction of the ozone
06:09
layer but thanks to the Montreal
06:10
Protocol we’ve dropped off the amount of
06:12
CFCs in the environment and over time
06:15
that ozone is going to build itself up
06:16
again and so did you learn the following
06:18
could you pause the video at this point
06:20
and fill in the blanks well let me do it
06:22
for you
06:22
ozone remember is oh three rather than
06:25
Oh two it mostly filters out UVC
06:28
radiation but also filtered some out of
06:30
the UVB this is ozone found in the
06:32
stratosphere or stratospheric ozone CFCs
06:35
release chlorine which formed the ozone
06:37
hole
06:38
the Montreal Protocol helped to avoid
06:41
that and the misconception you want to
06:43
avoid is that we’re not talking about
06:44
tropospheric ozone this polluting ozone
06:47
near the atmosphere we’re talking about
06:48
that protective good ozone high in the
06:51
atmosphere and I hope that was helpful
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This post was previously published on YouTube.