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Weather and climate

The weather

Weather starts with the sun. Sunlight heats up the earth, but not equally everywhere. Dark surfaces heat up faster than light ones. Land heats up faster than water. This leads to differences in temperature.

Warm air

Wherever the earth gets hotter, the air above it does too. This warm air expands and rises, creating space. Air from cooler areas flows in to fill this space. The result is wind. On a hot day this effect is stronger above tarmac than above water or grass.

Evaporation

Heat makes water evaporate. Sun and heat evaporate water from plants and puddles, among other things. The water doesn’t just disappear, however: it turns into water vapour in the air.

Clouds

Warm air can hold more water vapour than cold air. When very humid warm air cools down, the water vapour has to go somewhere. It slowly turns into liquid, forming tiny droplets. Lots of droplets together become clouds.

Precipitation

When the droplets inside a cloud get big and heavy enough, they fall.

These droplets can fall as rain, snow or hail. It all depends on the temperature of the layers of air they pass through.

Climate

Rain, wind, sun and temperature together make up the weather.

The weather can change from hour to hour, or it can stay the same for days. What we call climate is how often warm, cold, wet and dry periods come and go.

Climate change

The climate is slowly changing as weather patterns shift.

Some years are warmer or wetter than others. Over time, you see shifts in how often and how long some kinds of weather occur. Warm periods may last longer. Wet and dry spells no longer come at the same time every year.

Effects on nature

Changes in weather influence plants and animals. Most can cope with a few hot days. But if drought or heat lasts for weeks, plants lose water and stop growing. Insects may not become active until later, or might find less food. Some species can cope with this, others cannot.

When can you see climate changes in nature?

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