NatureWhy is the ocean blue? Water, sunlight and changing colours
The ocean is not blue only because it reflects the sky. Learn how water absorbs light and why sediment, algae and shallow sand change its colour.
Nature facts.
A closer look.
Oceans, living landscapes and the world around us. Start with a question below, then follow the evidence and further reading.
NatureNatureWhy is the ocean salty if rivers carry fresh water?
Trace ocean salt from weathered rocks to rivers and the seafloor. Understand why evaporation leaves salts behind and what 35 parts per thousand means.
NatureWhy do clouds float if water is heavier than air?
Clouds seem to defy gravity, but their tiny droplets, rising air and slow falling speed explain why they remain suspended.
NatureWhy does rain smell earthy before it starts?
That earthy smell has a name: petrichor. Learn how plant oils, soil compounds and raindrops create the scent people notice before or during rain.
NatureHow can whales sleep without drowning?
Whales must keep breathing consciously. Their unusual sleep strategy lets them rest while staying able to surface for air.
NatureWhy do deserts become so cold at night?
A desert can be scorching by day and surprisingly cold after sunset. Low humidity, clear skies and sparse vegetation explain the rapid change.
NatureHow can a lake release a deadly cloud?
Rare volcanic lakes can hold enormous amounts of dissolved carbon dioxide. A sudden disturbance may let the gas escape in a dangerous overturn.
NatureWhy do some animals see ultraviolet light?
Some birds, insects and other animals detect ultraviolet wavelengths that humans cannot see. Learn what this hidden information is used for.
NatureWhy do leaves change colour in autumn?
Green chlorophyll breaks down as daylight and temperature change. Other pigments become visible, while some leaves manufacture red pigments before falling.
NatureWhy do cats’ eyes shine in the dark?
A reflective layer behind the retina sends unused light back through the eye, increasing sensitivity. It also creates the visible eye-shine seen in headlights or a camera flash.
NatureWhy do volcanoes erupt?
Magma rises because it is buoyant and contains expanding gases. Pressure, fractures and magma supply determine whether an eruption is gentle or explosive.
NatureWhy do oceans have tides?
The Moon’s gravity pulls unevenly on Earth’s oceans, while the Sun adds a smaller effect. Earth’s rotation carries coastlines through bulges and tidal basins.
NatureWhy does honey last so long without spoiling?
Honey is low in available water, acidic and rich in sugars. Those conditions slow or stop many microbes, although contamination and moisture can change its stability.
NatureHow do bats navigate in complete darkness?
Many bats emit ultrasonic calls and analyse returning echoes. Timing and frequency changes reveal distance, shape and movement even when vision is limited.
NatureWhy do ocean waves keep moving after the wind stops?
Wind creates waves, but a swell can travel far beyond the storm that made it. Learn how wave energy moves through water.
NatureHow do fireflies produce light?
Fireflies use a chemical reaction in specialised organs. Oxygen, enzymes and a molecule called luciferin create flashes used for communication.
NatureWhy do birds fly in a V formation?
Large migrating birds can save energy by positioning themselves in the upwash from a neighbour’s wings. The lead position rotates because it is more demanding.
NatureWhy do zebras have stripes?
Stripe patterns may reduce biting flies and help zebras recognise one another. Their benefits are ecological, not a simple camouflage trick.
NatureWhy do flamingos stand on one leg?
Tucking one leg under the body reduces heat loss and may require surprisingly little muscular effort. The habit is not caused by salty water alone.
NatureWhy do mushrooms appear after rain?
Rain raises soil moisture and humidity, but it does not create mushrooms overnight. The visible cap is the fruiting body of a fungus whose network was already in the soil or wood.
NatureWhy do trees have rings?
Many trees add wood in seasonal growth pulses. Ring width records changing conditions, but rings are not a perfect calendar for every species or climate.
NatureWhy do some animals hibernate?
Hibernation lowers body temperature and metabolism when food is scarce. It saves energy, but animals still wake periodically and must manage water, oxygen and stored fuel.
NatureWhy does fog form near the ground?
Fog is a cloud at the surface. Learn how cooling, humidity and tiny particles turn invisible water vapour into a visible layer of droplets.
Find your rabbit hole.
Explore a subject, one question at a time.