Wild Weather

The heat of the sun drives our weather,

but water creates its many different faces.

I'm Donal MacIntyre. I'm about to follow water's journey

around the planet from the oceans to the clouds,

from a storm to a flood,

because I want to experience the awesome power it can unleash.

I'll meet people who've been at the mercy

of some of the wettest, wildest weather on Earth.

This is..."Wild Weather"!

We live on a water planet.

70 per cent of the surface is water.

Every living thing, including us, is made of it.

Right now there are twelve thousand billion tonnes of it,

literally hanging above our heads.

And it's this that fuels the world's weather.

Divide it by the amount of people who live on the planet -

this is how much each single one of us would have.

A cube of water measuring 46 metres high, wide and deep.

The same water we bathe in, we drink or flush away.

It's the same water that rains on us,

that forms the hurricanes and the monsoons.

It's the same water that's been here since Earth was formed.

All things being equal, this would be your share of the weather.

This is the same water that fell as rain before life itself began.

By now it has probably circled the planet over 8,000,000 times.

I'll follow the cycle your bit of water takes around the world.

Along the way, we'll see how it transforms itself

into every kind of weather on the planet.

I'm going to start my journey with water

in the wettest place in Western Europe - Bergen,

city of rain on Norway's western coast.

It rains here two out of every three days.

What's the one thing you need in a city like this?

Umbrellas, lots of them.

We have umbrellas for little rain, a lot of rain and storms.

For every occasion? Yes.

This city is so proud of its rain

they can it and sell it to tourists because they've lots of it.

To give you an idea.

If I stood here every day and night for the next 16 years,

I couldn't capture the volume of water

that falls on this city in a single year.

400,000 Olympic-size swimming pools of water

drench this place annually.

Crashing down on the roof of the average family house every month

is a staggering 18 tonnes of rain, that's 225 tonnes a year.

This place is seriously wet.

Devious tactics have to be employed by weather forecasters

to keep the people happy. Enter the blonde.

This is TV2, Bergen's local TV station.

Benedikte Rasmussen has the unenviable job

of presenting the weather.

It's not that difficult.

When the meteorologist says something long and difficult,

it's probably just going to rain.

The longest period of rain was in 1990.

I know because I've checked.

It rained from the 3rd of January to the 26th of March that year.

That's about 83 days.

I think I was quite fed up of rain after those days.

Prediction is a fine art.

Benedikte, what's happening here?

We're seeing how the weather will be in the days ahead.

How's it looking for Bergen?

I'm not sure, I think a little rain but not too bad.

How are these maps created?

Erm... I don't know!

Benedikte knows only slightly more about meteorology than I do,

but the ratings show that her glowing smile and confident presentation

keeps the audience happy and willing to receive

the somewhat familiar weather forecasts.

So why is this place so wet?

Daily, warm moist air flows in from the Atlantic,

hits the surrounding coastal mountains and is forced up.

As it rises, it cools, and the result is rain, tonnes of it.

Right this second, 18 million tonnes worth of rain

are falling somewhere on the planet.

If all this rain from the rooftops is going to join it,

there is only one way it can go, into the rivers.

Yesterday, what's cascading around me now was a rain shower in Bergen.

Before that, it could have been a monsoon rain cloud in India

or a cup of tea from the Ritz!

Today it's a river in Norway.

By tomorrow, it will have joined the North Sea.

After that, who knows where or what it will next become.

The water on our planet connects us all in truly remarkable ways.

All this water racing out into the North Sea

is about to join a vast weather-making ocean current.

I'll follow it to see some of the wettest, wildest weather on Earth.

In order to see where this current starts,

I have to travel north of Bergen.

There are many ocean currents that move water around our planet,

but there's one, a master current out in the North Atlantic,

that's the drive belt of our weather systems.

It's called the Thermohaline Conveyor.

Every ocean in the world is connected by it.

It's a 70,000-mile round trip that takes about 1,000 years to complete.

In that time, the water could have been part of every kind of weather

in Scotland or on the Serengeti.

It takes a phenomenal amount of energy

to drive this massive engine, the Thermohaline Conveyor.

What turns it on, what kick starts it?

To see for myself how it works, I have to get under the ice.

The secret lies in when this ocean turns to ice.

At minus two degree Celsius, sea water begins to freeze.

But this ice is made of fresh water,

as salt doesn't freeze and is locked out in the process.

This water is very salty, which makes it heavier, so it sinks.

As these billions of tonnes of cold, salty water fall,

they begin to flow south.

This sucks the warmer tropical waters up north to replace them.

This action drives a permanent ocean cycle.

From here, the route it takes is truly global.

As the cold waters plunge to the depths of the ocean,

they flow along the bottom and then around the Horn of Africa.

After about 500 years, it begins to warm up.

The Conveyor's first stop is in the Indian Ocean,

and, much later, in the Pacific Ocean,

where the whole system then curves around and the cycle repeats itself.

It's hard to imagine that the next time anyone sees the water I'm swimming in

will be when it rises as a warm current and laps a beach in India.

After a 6,000-mile journey within the Conveyor,

the water that fell as rain in Bergen over 500 years ago

is about to become part of the biggest rainstorm on the planet.

India hasn't seen a drop of rain for months.

Life is almost unbearable.

Well, almost!

But the monsoon is on its way.

Every summer around June 6th,

regular as clockwork, these clouds sweep in from the Indian Ocean

bringing life and death in their wake.

How it works is remarkably simple.

For most of the year, the prevailing winds come from the north.

Then, as summer heats up the country,

massive columns of hot air begin to rise

and, as they do, they suck in cooler moist air from the sea.

When these moist clouds break over land,

you get the fury of the monsoon downpour.

That cloud there is the beginning of the monsoon.

To see what's going on up there, I'm going to take a closer look.

I'm about to do something never done before in the monsoon.

I'm going to go up and experience the hot, humid monsoon winds.

To do that, I have to jump off this.

Flying with the birds has to be the most amazing and scariest way

of seeing the advance of the monsoon.

On a day like this, 75 billion tonnes worth of rain clouds

will sweep across this coast. A third will fall as rain.

It's staggeringly hard to imagine

that amount of rain falling anywhere.

Some clouds are ten miles thick and densely packed with water.

You don't want to be here when that lot breaks,

so for a little protection, a little warning,

you have to know what turns that water into raindrops.

So you have to look right into the heart of a cloud -

and right now that one there looks promising.

So how does a cloud produce a raindrop?

Up close, a cloud is just a swirling mass of water vapour.

Floating in it are comparatively huge particles of dust and pollen.

The vapour is attracted to the surface.

They collide with each other, getting bigger and heavier.

It takes a million of these droplets to make a raindrop only 2mm wide.

Gravity does the rest.

Monsoon downpours are epic.

In a few seconds, they can bring inches of water crashing to the ground.

For this brief period in the year,

the monsoon changes everybody's life.

A welcome relief from the tensions of the scorching heat.

When the rains arrive, India lets its hair down

and goes mad for football.

The rain softens the pitches, making them easy to play on.

I can't believe I'm 6,000 miles away from home

and I'm still playing in mud.

I doubt the monsoon is doing anything for my game

but it's doing wonders for my body.

All this rain can actually make you feel good.

As water falls through the air -

be it heavy rain, a waterfall or even a shower -

tiny particles in the air called ions become negatively charged.

This makes them sticky, which cleans the air

by literally dragging dirt and dust particles to the ground,

leaving it fresh and clear.

The cleaner the air, the quicker oxygen is delivered around the body,

and it's this that makes us feel good.

Which is why the shower is where most of us have our best thoughts.

All this clean air has another effect on the local population.

To find out what, I went to see my friend Antonio.

Antonio, it's raining heavily, I love the sound of this rain.

Yes, it is beautiful. When it rains it's like music.

When it rains, especially very heavily, you love to stay at home,

and a lot of people conceive at this time as I see it.

So the rain brings babies too? Maybe.

Lots of water babies.

Nine months after the monsoon, the birth rate leaps.

It's an intense period, because in a few months' time

those monsoon breezes rushing in from the sea

will reverse themselves, leaving just the merciless heat of the sun.

India only manages to hold on to ten per cent of all that rain.

The rest leaves the country by the thousands of rivers and streams

that break its shores.

Every second, billions of gallons pour into the oceans