Air: Milos Radakovich

For the most part, the air around
us is invisible, yet we are constantly
confronted by evidence
that it’s there.

In fact, nearly 15 pounds (7kg) of
it is currently resting on every
square inch (6.5 cm2)
of your body. No wonder you’re having
such a hard time getting up in the morning.

Another way to think of it is that every square inch of the Earth’s
surface is supporting a column of air hundreds of miles high,
reaching all the way to space. At sea level, the weight of that
inch-square column is 14.7 pounds (6.7kg), also referred to as
one atmosphere.

In fact, atmosphere is one of the things that make our Earth so
special; not only its composition – Nitrogen, Oxygen, and other
gasses like CO2, Methane, Argon – but the fact that we have one.

Mars’ atmosphere is mostly CO2, but is only one tenth the density
of ours. Venus has a super dense, 800o
F (427oC)  atmosphere,
while Mercury and our Moon have none at all. The outer planets
– gas giants – are mostly atmosphere, with small rocky cores.

When air moves, we call it wind. Over the millennia we have
learned to harness some of the energy of moving air to transport
people and cargo, mill grain, pump water, make electricity, and
even fly kites.

Most of the time, air does its work invisibly; we see its movements
only indirectly, in the dance of banners and amber waves
of grain, or in the destructiveness of tornadoes and hurricanes.
In a way, that which we call weather renders the atmosphere
visible, if only temporarily.

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