ENVIRONMENT AND ENERGY
25
Life on earth –
something to
think about
Let’s take a walk: imagine yourself taking a short five
kilometre walk along the esplanade of a seaside resort.
By Chris Kyle
Now, if the daytime temperature was a pleasant to
warm 25 degrees Celsius, it would remain pretty
much the same when you arrived at your destination
five kilometres away (depending on the time of day
of course). On your arrival, you would still be able to
breathe easily and freely with a good flow of oxygen
being fed to your body and brain and you would feel
warm, happy, and comfortable. No problem — all
good — time for a nice cold beer!
But now imagine if it was possible to walk vertically up into
the atmosphere from the same departure point and for
the same short distance of five kilometres — the picture
would be radically different because you would now be
5 000 metres above sea level!
Dressed in your T-shirt and sandals, you would soon start
getting very cold because the temperature could now be
as low as minus five to minus seven degrees Celsius,
depending on the prevailing environmental lapse rate.
Your body core temperature would plummet rapidly, and
you would soon start suffering the effects of hypothermia.
If left in this state for some time, your speech would
become slurred (no need for a cold beer), and your thought
patterns would become more and more confused. Your
heart and vital organs would slowly start shutting down.
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But that’s not all folks: to compound the problems, in the
rarefied air, at this altitude there would be little oxygen to
feed your body and brain, and hypoxia (lack of oxygen)
would also set in. You would die some time later and, in
the process, you would wish you had never gone on that
vertical walk.
SUCH A THIN LAYER WITH A BIG ROLE
A profound thought is that the life-sustaining layer of
the atmosphere that enshrouds the surface of the earth
is shockingly thin. The average diameter of the earth is
roughly 12 700 kilometres; yet, the layer that is capable
of supporting human life, without the use of specialised
equipment and apparatus, is only four to five kilometres
thick (which is quite literally less than 0.001%).
To put a scale to this or to put it into perspective: imagine
a soccer ball wrapped in a very thin layer of cling wrap.
The thickness of the cling wrap would represent the
thickness of the life-sustaining layer of atmosphere within
which human life can exist. Not very thick at all and also
very fragile.
LET IT RAIN
The part of the atmosphere within which Earths’ weather
occurs is called the troposphere. The troposphere extends
June 2018 Volume 24 I Number 4