Page 61 - How It Works - Book of Amazing Answers To Curious Questions, 12

---- Environment Q�
_______________

How does the

ozone worl<?

We may hear about it a lot, and mainly how we're slowly
destroying it, but just what is the ozone layer?

he ozone layer is essentially Mother Earth's So how does the ozone protect us? Ozone molecules
safety net, residing some 50 kilometres above consist of three oxygen atoms, hence the chemical
T the planet's surface. Created from 03, or ozone formula OJ. Stratospheric ozone absorbs UVB
gas, it is up to 20 kilometres thick and 90 per cent of high-energy radiation, as well as energetic electrons,
this gas can be found up on the Earth's stratosphere. which in turn splits the 03 into an 0 atom and an 02
This protective gas is vital to the nurturing oflife on molecule. When the 0 atom soon encounters another
our planet, and here's why. 02 molecule they re-merge and recreate OJ. This
Ozone gases act as a shield against ultra violet, or means that the ozone layer absorbs the UVB without
UVB, radiation. These harmful emissions are sent being consumed. The ozone layer absorbs up to 99 per
through the Sun's rays, and without the ozone would cent of the Sun's high frequency UV light rays,
severely affect the planet's ecological balance, transforming this into heat after its combustible
damaging bio-diversity. UVB rays reduce plankton atomic reaction, therefore creating the stratosphere
levels in the ocean, subsequently diminishing fish itself. This effectively incubates life on Earth.
stock. Plant growth would also diminish in turn But ozone doesn't reside only in the world above.
disrupting agricultural productivity. This would in This gas is also present in the layer around the
turn affect the human populace, who would be Earth's surface. Ten to 18km above us, this is known
exposed to an increase in skin-related diseases such as the tropospheric ozone or 'bad ozone', comparative
as cancer. to the function of the stratosphere.
This ozone occurs naturally in small doses,
initiating the removal of hydrocarbons, released
by plants and soil, or appearing from small
amounts of stratospheric ozone, which
occasionally migrate down to the
Earth's surface.
However, it gets a bad reputation
due to its interaction of ultraviolet
light, with volatile organic
compounds and nitrogen
oxides, emitted by fossil-fuel
powered machines and
internal combustion
engines. This produces
high levels of ozone,
which are formed in
high temperature
conditions, ultimately
toxic to all forms of
organic life.

How big is the hole in the ozon laye

he ozone hole refers to an area of Antarctica from the rest of the world. This allows
Tdepletion over the Antarctic region of special polar stratospheric clouds to form at
Earth. The planet's ozone records a decline of about 80,000 feet altitude. These concentrate
four per cent per decade in total volume but atmosphere pollutant.
much larger loses are recorded in the When spring returns after the sunless winter
stratospheric ozone over Earth's polar region, period the ozone is depleted causing the ozone
however this is seasonal condition. These areas' hole. The largest ever recorded ozone hole
unique atmospheric conditions see the most occurred in 2006, at 20.6 million square miles. At
impact. Strong winds blow around the continent present the ozone hole is recorded at between 21
forming a polar vortex, isolating the air over and 24 million square kilometres.

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