Welcome to the Bedtime scientist.
Tonight we aren't going to travel down to the bottom of the
sea. We're not even going to leave
the spot where you're resting right now.
Tonight, all we have to do is look up, because there's
something that drifts over your head almost every day, something
you've seen 1000 times that turns out to be far stranger and
far heavier than it looks. Take a deep breath in, let it
out, close your eyes and imagine with me.
It's the end of the day and you've gone outside to lie back
in the cool grass, nowhere to be, nothing to do but look up
and let your mind wander. The air has started to cool.
Somewhere nearby a cricket is making its small evening sound,
and above you is the sky, wide open.
At first it might look like there's nothing there, but then
you notice them. Clouds.
Some are long and thin, like pale brush strokes.
Some are wide and rounded right along the top edge 1 is so big
it seems to move like a slow ship crossing an invisible sea.
From down here, a cloud looks soft, light, like it's drifting
along without any effort at all. A cloud is made of water.
Not puddles, not raindrops you could catch in your hand.
Tiny droplets so small you could never hold just one, so light on
their own that the air keeps them floating.
They form around something even smaller.
A speck of dust. A grain of salt lifted off the
ocean. A bit of pollen from a flower.
Water gathers around the tiny speck and a droplet begins.
Then another. Then another.
Millions of them. Sometimes billions.
And when scientists carefully weigh one of those big puffy
white clouds, the kind that drifts across the sky on a
summer afternoon, they find something hard to believe.
It can weigh £1,000,000, a million pounds heavier than a
long line of elephants, heavier than a row of trucks parked end
to end. But there it is, floating
quietly over your head. So how does something that heavy
stay up? The weight is spread out.
The water in a cloud isn't gathered into one heavy bucket.
It's scattered into those countless tiny droplets drifting
through an enormous stretch of air, and the air is moving.
Warm air rises up from the ground all the time, and that
slow rising is enough to hold each tiny droplet up.
So the cloud is heavy and the cloud floats.
Both of those are true at the very same time.
From far away, a cloud looks like one simple thing, white and
plain, easy to Passover. But inside it, there are more
droplets than you could ever count.
Inside it, there's motion. Inside it there's weight.
A whole hidden world, all held together in one soft shape,
drifting along like it weighs nothing.
The water inside it has been somewhere before too.
The water in a cloud above you tonight might once have been
deep in the ocean where no sunlight could reach.
Before that rain on a forest, and before that, frozen still
inside a mountain glacier. Long before anyone alive today
was born. And now here it is again, lifted
back into the sky, gathered into something bright and floating.
A cloud doesn't hold on forever, though.
As more water gathers, the droplets grow.
They bump into each other and join and grow heavier and
heavier, and there comes a point and the rising air can't hold
them up any longer. So the cloud does the next
thing. Clouds do.
It lets go. The rain begins.
Not because anything went wrong, not because the cloud failed.
The cloud carried what it could for as long as it could, and
then the time came, and letting go was simply the next part.
And what it lets go of isn't lost.
It soaks into the ground and feeds what grows there.
Even the letting go turns into something the world needs.
So picture 1. Cloud now, drifting slowly above
you, not rushing anywhere, not trying to be any other shape,
just moving along with the air, holding what it holds, and when
the time comes, letting some of it go.
The sky knows how to carry it, the earth knows how to catch it,
and everything keeps moving. You carried a lot today too.
Some of it was light and some of it was heavy.
A hard moment, a worry that stayed a while, a feeling too
big to find the words for. All of it real, even the parts
no one else could see from the outside.
You don't have to keep holding it now.
You can set it down. You can let it move on through
the way rain moves on through the soil into something quieter.
Setting it down isn't failing, it's just the next part.
You can let something else do the holding for a while, and you
don't have to remember any of how clouds work.
Not the speck, not the £1,000,000.
You can let all of it drift off too.
It'll still be true in the morning, so let yourself grow
heavy, let the day grow quiet, and let your mind drift back up
to that wide open sky the way it did in the grass, with nowhere
to be and nothing to carry, just watching the clouds go by.
And just before you drift off to dream of clouds drifting slowly
overhead, tiny droplets too small to see, and all the water
that has traveled the whole world just to float above you.
Tonight, I want you to know something about you.
Your mind is a wonderful thing, so full of curiosity, and I like
your mind just the way it wonders.
I'll be back again soon to wonder more with you.