Thin Air

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0120110112

We not only live in the air, we live because of it.

And air is about much more than just breathing.

It is a transformer and a protector, though ultimately also a poison.

At ground level, photosynthesis transforms air miraculously into solid food without which every creature on Earth would starve.

It wraps our planet in a blanket of warmth.

It brings us wind and rain and fire.

It sustains our bodies and at the same time it burns them up, slowly, from the inside.

The atmosphere provides a floating mirror for intercontinental radio signals and its outer layers soak up flares of deadly radiation from the Sun.

In the first episode, Gabrielle Walker experiences air - and weighs it.

At ground level, the air is not as 'thin' as we might imagine.

The Royal Albert Hall, in its day one of the largest volumes of air enclosed in a single span may seem to be full of nothing, but in fact, the air inside weighs 30 tons! On the other hand, not much further away than the next city, the air is so tenuous as to be unbreathable! That is in the 'up' direction.

In between is a gaseous ocean in which Gabrielle takes a swim - floating on air, flying a glider and chasing the storm clouds that bring us our weather.

Producer: Martin Redfern.

Gabrielle Walker explores our atmosphere, the ocean of air on which we all depend.

0220110119

We not only live in the air, we live because of it.

Air is about much more than breathing.

It is a transformer and a protector, though ultimately also a poison.

It wraps our planet in a blanket of warmth.

It brings us wind and rain and fire.

It sustains our bodies and at the same time it burns them up, slowly, from the inside.

In this episode, Gabrielle Walker investigates the good side - and the bad - of two components of air: carbon dioxide and oxygen.

Carbon Dioxide makes up a tiny fraction of one percent of air, yet it at once protects, transforms and threatens life on Earth.

CO2 is infamous for its contribution to the greenhouse effect that is causing global warming.

But without it we would both freeze and starve.

It is also the basis of everything we eat.

The mass of all plants and hence the creatures that feed on them comes from carbon dioxide.

Billions of years ago, as the young Sun began to warm, bacteria and primitive algae began their insulating blanket, fossilising the air as limestone, coal and chalk.

Now we are releasing that carbon to the air again, double-glazing the global greenhouse.

The greatest transformer in air is oxygen.

It is the giver and taker of life.

Without it living things cannot be vigorous - or larger than a pinhead.

Yet it is also the bringer of death.

When bacteria started releasing it as a waste gas, a billion or more years ago, it was the worst pollution incident in the history of the planet.

Life was forced to hide or evolve.

Even though we have adapted to depend on oxygen, we are playing with fire.

In a slow and mostly controlled way, oxygen burns up the food we eat.

It also chars the genes, molecules and cells within us, bringing about ageing and, ultimately death.

Producer: Martin Redfern.

Gabrielle Walker explores how our atmosphere both protects and destroys us.

03 LAST20110126

On August 16th 1960 at 7AM, Joe Kittinger was hanging in the sky twenty miles above New Mexico.

He was so high that the sky seemed black and he could see the luminous glow of the atmosphere, curving away around the planet beneath him.

Had his pressure suit failed, he would have died.

As it was, he moved to the edge of the gondola beneath his helium-filled balloon.

and jumped.

For four minutes and 37 seconds, he fell free; at first with little sensation of motion, from near-vacuum to the coldest air around.

Then, as the rushing air began to slow him, he entered the troposphere, where all the clouds, weather and life resides.

His parachute opened, bringing him home to a desert that, after where he'd been, seemed like the Garden of Eden.

On the way down, he crossed the ozone layer, where a story of serendipity and surprise was later to unfold; an example of the fragility of the air, our blindness to our actions and our resourcefulness in recognising and then fixing a problem.

By the time British scientists spotted that there was a hole in the ozone layer above Antarctica so big that space scientists hadn't noticed it, it was almost too late.

Gabrielle Walker follows Kittinger's short journey through the upper atmosphere and discovers how it protects us from the radiation of space and reflects our radio messages around the planet.

She travels to the Arctic to witness the ultimate high-altitude aerial battleground between space and atmosphere: the Northern Lights.

Producer: Martin Redfern.

Gabrielle Walker explores Earth's protecting veil, the upper atmosphere.