Ozone on Bondi Beach - Periodic Table of Videos

I'm on Bondi Beach in Sydney Australia and I want to talk to you about ozone because there's an interesting paper that's just been published about ozone and the effect on the weather in Australia let's start with oxygen in the atmosphere that is oxygen perhaps 30 kilometers above the Earth's surface now imagine an o2 molecule here this can absorb ultraviolet light from the Sun and the energy of the absorb light can blow the molecule apart so you now have two oxygen atoms and because the atmospheric pressure is low these will fly apart here I've got another oxygen atom that's been formed by dissociating o - and if it flies along and hits another OH - molecule so we have o plus o - they can react to form ozone which is oh three and oh three ozone is another form of oxygen which is highly colored it's a sort of dark blue color the molecule and as it sits in the upper atmosphere it absorbs the harmful UV light and stops it coming down to the Earth's surface with very high intensity and protects us all from the effects of the sunlight and in fact the ozone absorbs light itself and falls apart to form o to an oxygen but this oxygen atom can recombine to make more ozone so there's an equilibrium the ozone is falling apart but it's being made at the same rate as it falls apart this is what happened until people started using aerosols for things like styling their hair you know and when they started making these aerosols in the aerosols they put a molecule rather like this which has carbon in the middle three fluorine atoms and a chlorine atom so this is C F 3 CL I've used another earth but it's much bigger so this is chlorine so here we have a molecule which in itself is completely harmless with three fluorines and a chlorine bonded to the carbon but when this when you spray your hair or you used to with old-fashioned hair sprays these molecules went into the atmosphere and floated around and eventually got up to 30 kilometers high and when they got there this molecule would absorb UV light and expel the chlorine atom so now high up above your surface as well as the oxygen atoms you have a chlorine atom and the chlorine atom could can react with ozone and remove one of the oxygens so you now have CL o CL o is not very stable and so it reacts further to release the chlorine atom so the chlorine atom will go on and knock out one ozone molecule after another until it's probably knocked out perhaps a thousand ozone molecules the effect is that these molecules here with fluorine chlorine and carbon the so called CFCs can if they get into the atmosphere start destroying the ozone layer what is particularly striking is the effect that you get over the poles the Antarctic and the Arctic because over the Antarctic and Arctic you get very small ice crystals in the air and the chlorine atoms can be adsorbed onto the surface of the ice crystals during the polar night when the Sun is not shining onto the surface of the of the earth and then when the Sun comes back up in the spring like the spring now in the southern hemisphere then a large amount of chlorine is released all at once and it can completely destroy the ozone causing a so-called ozone hole where the UV light can get right down to the Earth's surface of course there's very little life in the Antarctic so the UV light going down does not affect many organisms but what it does do is that it changes circulation patterns in the atmosphere and this recent paper suggests that the whole ozone hole over the Antarctic is in fact causing rainfall to shift southwards from Australia and therefore might explain the droughts and things that have been happening recently on this continent now you might ask why is the effect worse in the southern hemisphere than the northern hemisphere and the answer is really simple because if you look at the earth let's turn the chlorine back into the earth and look at the earth you can see the Antarctic is a landmass whereas the Arctic on the other side is sea so the temperatures over the Antarctic are much lower than those of the Arctic so you get far more of these ice crystals in the air and therefore the effect on the chlorine and the atmospheric chemistry is much more pronounced scientists first discovered the effects of CFCs and chlorine in the atmosphere in the late 1970s and shortly afterwards the use of CFCs in aerosols was banned but so many of them have already been released in the atmosphere they're still slowly drifting up to the upper atmosphere from the near the ground where we first released them so the effect with the Arctic and Antarctic ozone holes is going to persist for many more years but eventually the CFCs will be washed out of the atmosphere and all being well this problem will disappear there's one extra twist the ozone in the upper atmosphere is really very beneficial life on Earth wouldn't really exist without it the ozone in the lower atmosphere near the Earth's surface is not at all good because ozone is a very reactive molecule it can lose oxygen in all sorts of different ways reacting with organic compounds and can cause serious health problems to people and over the last century or so the amount of ozone near the Earth's surface has increased because of a number of reactions in the atmosphere promoted by the Sun usually involving oxides of nitrogen which can be produced by emissions from car exhausts and so on and recently the Royal Society produced a report on the effect of ozone near the Earth's surface so called ground-level ozone their real worries that ozone at ground level is a serious health problem because when the weather is very hot and bright the ozone levels go up and this contributes to deaths particularly during heat waves

Channel: Periodic Videos

Views: 365,386

Rating: 4.9505291 out of 5

Keywords: ozone, layer, CFC, Bondi, Beach, Sydney, Australia, Martyn, Poliakoff, Chlorofluorocarbon

Id: YxsxfsYxA4s

Length: 8min 9sec (489 seconds)

Published: Mon Oct 03 2011

Reddit Comments

[u/MonaganX]

About half the title was completely unnecessary.

[u/avondalian]

He got that smart hair

[u/robertshammer]

Bondi beach