Dear Josha, it’s pretty cold right now. It’s snowing, the ground is slippery. Maybe you’ve already built a snowman or two. Other days it rains, then the sun shines and the day after tomorrow the wind blows your hat off your head. This may seem like magic to you, but it’s a pretty sophisticated interaction of sun, air and water.
Everything starts with the sun. It is something like the engine for our weather. “The sun is the only source of energy available to the atmosphere to get all the weather events going,” explains meteorologist Andreas Walter. Meteorologists are weather experts.
The atmosphere surrounds our Earth. It is also simply called air and is everywhere. The sun’s job: It warms the air on Earth – but not to the same extent everywhere. It is much warmer at the equator than at the poles. And because the Earth is slightly askew to the sun, it is summer here when it is winter in the southern hemisphere and vice versa.
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The earth doesn’t like it when somewhere is much warmer or colder than elsewhere. She always tries to balance everything. The meteorologist Walter says: “Nature and therefore the atmosphere are always striving to achieve balance.” This means: Warm air from the south wants to go north, cold air from the north wants to go south. And it is precisely this movement that gets our weather going.
The different exposure to the sun also causes the wind. Warm air is lighter than cold air and rises upwards. From where there is a lot of air – this is called high pressure – air flows to where there is little, which is then called low pressure. “Wind always blows from high to low,” explains Walter. That’s why we sometimes feel it quite strongly.
And the rain? It has to do with water. Water evaporates over seas and lakes, becomes invisible water vapor and rises into the air. The higher it goes, the colder it gets. The steam turns back into tiny water droplets and clouds form. If the droplets become too heavy, they fall down as rain. This water flows back into the sea via streams and rivers. Then everything starts again. This is called the water cycle.
Luckily we have four seasons in which the weather is always different. So there is something for everyone. Which weather do you prefer?