Earth & sky
Earth & sky
Weather, light, and the air around us
It thins rather than ends
Where Does the Air Stop?
The atmosphere has no boundary — air just gets thinner with height until it fades into space.
Let’s go →A weak layer buried inside
Why Does a Snowy Slope Suddenly Let Go?
Avalanches happen because snow builds in layers, and a weak buried layer can collapse and release the slab above.
Let’s go →Weighing the sky
How Does a Barometer Work?
A barometer measures the weight of air overhead, which falls before storms and rises before fine weather.
Let’s go →Ice you cannot see
Why Is Black Ice So Dangerous?
Black ice is a clear film of frozen water that looks like wet road and removes almost all grip.
Let’s go →Light getting bounced
Why Is the Sky Blue?
Air scatters blue light sideways, so it reaches your eyes from everywhere.
Let’s go →Water dissolving stone
How Do Caves Form?
Caves form when faintly acidic water slowly dissolves limestone away.
Let’s go →Reading the sky
Why Do Clouds Have Different Shapes?
Puffy, flat or wispy — a cloud's shape shows how the air under it is moving.
Let’s go →Droplets too small to fall
How Does Something That Heavy Float?
Clouds float because they are made of droplets so small that air resistance nearly cancels their fall.
Let’s go →Because it was one
Why Does the Map Look Like a Jigsaw?
South America and Africa fit together because they really were joined, and the sea floor between them is still growing.
Let’s go →Where the rain never arrives
Why Are Deserts Dry?
Deserts are dry because sinking air, mountains or distance keep the rain away.
Let’s go →The temperature where air gives up
What Is the Dew Point?
The dew point is the temperature at which air can no longer hold its water as vapour.
Let’s go →How hard the air pushed
Why Is Some Rain Gentle and Some Rain Heavy?
Heavy rain comes from tall clouds where rising air held drops up until they were huge.
Let’s go →Rain going missing
What Is a Drought?
A drought is a long stretch of much less water than a place normally depends on.
Let’s go →Rock finally slipping
Why Does the Ground Shake?
Earthquakes happen when stuck slabs of rock suddenly slip past each other.
Let’s go →Patience with sandpaper
How Do Rivers Carve Canyons?
Rivers cut canyons by dragging sand and stones that grind the rock away.
Let’s go →Escaping one at a time
Where Does a Puddle Go?
Puddles vanish because fast-moving surface molecules escape into the air as vapour.
Let’s go →When the ground stops drinking
Why Do Rivers Flood?
Floods happen when rain arrives faster than the soil can soak it up.
Let’s go →A cloud on the ground
What Is Fog?
Fog is simply a cloud that has formed at ground level.
Let’s go →Rock replacing bone
How Does a Fossil Form?
Fossils form when minerals slowly replace buried bone, copying its shape in stone.
Let’s go →Air letting go of water
Why Is the Grass Wet in the Morning?
Dew and frost form because cold surfaces make the air beside them give up water it can no longer carry.
Let’s go →A kettle with a narrow neck
Why Does the Ground Shoot Boiling Water?
A geyser erupts because pressure holds superheated water back until a small boil triggers a chain reaction.
Let’s go →Ice that flows
How Do Glaciers Move?
Glaciers are ice piled so deep that it deforms and flows slowly downhill.
Let’s go →A blanket that lets light in
How Does the Air Keep Earth Warm?
Greenhouse gases let sunlight in but trap the heat radiating back out, keeping Earth far warmer than it would be.
Let’s go →Soaked rock, not caverns
Where Is Water Underground?
Groundwater sits in the tiny spaces between grains of rock, not in hidden lakes.
Let’s go →Ice going round again
How Does Hail Form?
Hailstones grow by cycling up and down inside a storm, adding a layer each trip.
Let’s go →Air that will not leave
What Makes a Heatwave?
A heatwave happens when sinking, stuck air blocks clouds and lets heat build day after day.
Let’s go →When sweat stops working
Why Do Some Hot Days Feel Worse Than Others?
Humid air is already full of water, so your sweat cannot evaporate and cool you.
Let’s go →A heat engine over warm water
How Do Hurricanes Form?
Hurricanes are giant spinning storms powered by heat released from warm ocean water.
Let’s go →One-ninth showing
Why Do Icebergs Float So Low?
Ice is only slightly lighter than water, so about nine-tenths of an iceberg is submerged.
Let’s go →Four different ways
How Does a New Island Appear?
Islands appear in four main ways: volcanic building, coral growth, being cut off, or falling sea level.
Let’s go →A fast band steering the weather
What Is the River of Wind Up High?
Jet streams are ribbons of fast high wind formed where warm and cold air meet, and they steer our weather.
Let’s go →Sorted by weight
What Is Inside the Earth?
Earth has layers because heavy metal sank to the centre while it was still molten.
Let’s go →A giant spark
What Is Lightning?
Lightning is a huge electric spark between a charged cloud and the ground.
Let’s go →Giving the strike an easy road
How Does a Lightning Rod Protect a House?
A lightning rod gives a strike an easy metal route to the ground, away from the building.
Let’s go →Atoms in formation
What Is a Mineral?
A mineral is a natural solid with a fixed recipe and a repeating atomic pattern.
Let’s go →A sea breeze the size of a continent
What Is a Monsoon?
A monsoon is a continent-sized sea breeze that reverses with the seasons.
Let’s go →Crust crumpling
How Do Mountains Grow?
Mountains form where colliding plates crumple the crust upward.
Let’s go →Salt arrives and never leaves
Why Is the Sea Salty?
The sea is salty because rivers deliver salt and only fresh water evaporates out.
Let’s go →Warm and windy beats damp and still
Why Do Puddles Dry Slower Some Days?
Puddles dry fastest in warm, windy air and barely at all in damp air, because molecules land back in as fast as they leave.
Let’s go →The sky letting go
Where Does Rain Come From?
Rain falls when tiny cloud droplets merge until they are too heavy to float.
Let’s go →The air arrives empty
Why Is One Side of a Mountain Dry?
Air dumps its rain climbing a mountain, so the far side gets dry wind and no water.
Let’s go →Raindrops as prisms
How Does a Rainbow Work?
Raindrops bend and reflect sunlight, splitting it into a curved band of colour.
Let’s go →An old rhyme, half right
Does a Red Sky Really Predict the Weather?
A red sunset means clear dry air to the west, which in Britain is tomorrow's weather.
Let’s go →Erosion on the outside
Why Do Rivers Bend?
Rivers bend because water cuts the outer bank and deposits on the inner one.
Let’s go →Nothing is permanent
Can a Rock Turn Into a Different Rock?
Rocks continually change type, as heat, pressure and weathering recycle them into one another.
Let’s go →Mountains, eventually
Where Does a Beach Come From?
Sand is what remains after rock is broken down and everything softer has washed away.
Let’s go →Water eats red light
Why Is the Sea Blue?
The sea looks blue because water absorbs red light quickly and only blue makes it back to your eyes.
Let’s go →Land and sea disagree
Why Is It Windy at the Beach?
Land warms faster than water, so air rises over the land and pulls a breeze in from the sea.
Let’s go →The ground is still catching up
Why Is the Hottest Month Not the Longest Day?
The hottest weeks come after midsummer because land and sea are still absorbing more heat than they lose.
Let’s go →Plants moving without moving
How Do Seeds Travel?
Seeds travel by wind, water, animals or launching, because plants cannot move.
Let’s go →A flake's journey down
Why Does It Sometimes Rain and Snow at Once?
Sleet falls when a snowflake half-melts on the way down and never gets to finish.
Let’s go →Ice with air in it
Why Is Snow White and Fluffy?
Snowflakes are ice crystals, and snow looks white because of countless surfaces bouncing light.
Let’s go →Six arms, one journey
Why Is Every Snowflake Different?
Ice always grows six ways, but each flake's journey through the cloud is unique.
Let’s go →Rock, remains and life
What Is Dirt Actually Made Of?
Soil is ground-up rock mixed with decayed remains, air, water and more living things than you would believe.
Let’s go →Light not getting through
Why Do Storm Clouds Look Dark?
Storm clouds look dark because they are thick enough to stop light reaching you.
Let’s go →Counting between flash and bang
How Far Away Is the Storm?
Count the seconds between lightning and thunder and divide by three for the distance in kilometres.
Let’s go →Wind piling up water
Why Does the Sea Rise in a Storm?
Low pressure lifts the sea slightly and strong wind piles it against the coast.
Let’s go →Light taking the long way
Why Are Sunsets Orange?
At sunset light travels through much more air, which strips out the blue.
Let’s go →Air exploding
Why Does Thunder Rumble?
Thunder is the sound of air exploding away from a lightning bolt.
Let’s go →The Moon pulling
Why Does the Sea Go In and Out?
Tides happen because the Moon pulls the ocean into bulges that Earth spins through.
Let’s go →A spin tipped upright
How Does a Tornado Form?
A tornado is a horizontal rolling column of air tipped upright and stretched by a storm.
Let’s go →A wave that is all the way down
Why Are Tsunamis So Dangerous?
A tsunami is dangerous because it moves the whole ocean depth, not just the top.
Let’s go →Pressure finding a way out
Why Do Volcanoes Erupt?
Volcanoes erupt when buoyant molten rock and expanding gas force their way to the surface.
Let’s go →A loop with no end
Where Does Water Go?
Water evaporates, forms clouds, rains down and flows back to the sea, forever.
Let’s go →Energy moving, water staying
Do Waves Carry Water Along?
Ocean waves carry energy across the water while the water itself circles in place.
Let’s go →Physics run forward
How Can Anyone Predict Tomorrow?
A forecast measures today's air everywhere and calculates it forward using known physics.
Let’s go →Lines, triangles and half-circles
How Do You Read a Weather Map?
Weather map lines join places of equal pressure, and the fronts show where air masses collide.
Let’s go →Fire as a gardener
Why Do Some Forests Need to Burn?
Some forests depend on regular small fires, and preventing them lets fuel build until the fire is catastrophic.
Let’s go →Air evening things out
What Makes Wind Blow?
Wind is air flowing from high pressure to low pressure because the Sun heats unevenly.
Let’s go →Losing your warm coat of air
Why Does Wind Make You Colder?
Wind blows away the warm layer of air your skin has heated, so you lose heat much faster.
Let’s go →Named for where it starts
Where Does the Wind Come From?
Wind is named for the direction it comes from, which tells you what kind of air is arriving.
Let’s go →