What is sunlight used for?

The sun - the basis for our life

The sun gives light.

Why do we need sunlight?
The light of the sun is so strong that we don't need additional lighting during the day. Even when it is foggy and cloudy, the sun shines so much light on the earth to make life possible.

Every square meter on the sun shines brighter than a million light bulbs. Even your best flashlight only comes a few meters away and even a super-powerful laser beam can only illuminate individual points, but never illuminate the entire globe.

Without the sunlight it would be completely dark on earth. Even the moon would not give us any light at night, since it only deflects the sun's rays towards us and does not shine itself. Without the sun, the earth would be completely bare of vegetation. Every plant needs light to live and grow. The plants even convert the light into oxygen, which humans and animals need to breathe.
And did you know that sunlight is even important for our bones? When we move around in the sun, vitamin D is formed and we need it to build up our bones. As a result, people who rarely or never move in the sun often have porous bones that break easily.

The sun gives off warmth

Would it be as cold on earth as at the North Pole without the sun?
The earth is exactly the right distance from the sun without burning. It is so far away from the sun that just as much heat arrives as all humans, animals and plants need to live. If the sun went out, life would no longer be possible after a few weeks. The water and air would freeze into sheets of ice.

It would even be much colder than the freezer in your kitchen, where it can get down to -18C. And it would be even colder than at the North Pole, even though it's pretty cold there. Normally the temperature in Antarctica is -20C. to -50C. A temperature of -89.2C has even been measured once before. But that is really the lowest temperature that has ever been recorded on earth.

And without the sun it would be much, much colder. The temperature would be close to absolute zero of –273C. Even a polar bear would freeze to death at this temperature, and even with your thickest down jacket you couldn't stand this temperature for long. But don't worry, the sun will shine for billions of years and provide us with its warmth.


The sun makes for rain

Why doesn't the sea overflow?
You have probably wondered why the sea doesn't overflow. After all, all rivers, streams and also the rain constantly transport new water into the sea, so that at some point it would have to spill over the shore.

This is because water all over the world is in a cycle: the warm rays of the sun evaporate water from the earth's surface, including the oceans. That is why the sea level always stays the same. You have probably seen boiling water in a pot that gradually evaporates. But water doesn't have to boil until it can evaporate, and puddles also disappear from the streets over time, because the water evaporates due to the warmth of the sun. The evaporated water then rises until it meets colder air. There the fine droplets of dust particles precipitate and form clouds.

You can also watch this at home in the kitchen or bathroom when the water vapor condenses on the cool mirror or window pane. If the cloud becomes too heavy or gets stuck on a mountain, the water falls on the earth as precipitation and fills the seas, rivers and lakes again. The water that falls to the bottom seeps into the groundwater and then returns to the rivers. Even drops of water that fall on a street and cannot seep away, evaporate through the sun and are part of the water cycle again.

The sun creates wind

Why is it always windy by the sea?
You've probably already let the wind blow around your nose. But would you have thought that the sun is also responsible for the wind? The sun does not heat our earth evenly. Some layers of air warm up faster than others and that is why there are warm and cold air layers on earth.

The warm layers of air attract the cold air and this creates an air current and depending on the strength we say breeze, storm, hurricane or just wind to this current. You can also feel this very clearly at the sea: a more or less strong wind is constantly blowing there. When the sun is shining, the air warms up faster over land than over the sea. The warmer air expands and rises. There is now more space on the floor and the cold air flows into the space that has become free. This creates wind, a real sea breeze. Incidentally, the land cools down faster at night, which means that the wind turns at night and blows out onto the sea.


Source: with the kind permission of SMA Solar Technology AG
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