Sky: only blue because we see it that way | Photo: Shutterstock

The sky is blue. It could be yellow, green or red. But it's blue. Blame it on the atmosphere and on our eyes.

What would happen if we woke up one day, open the bedroom window, and outside the sun shone in a brown sky? It would be quite surreal. The truth is that the sky is not brown only by chance.

The explanation for the fact that the sky is blue is quite simple. The light emitted by the sun crosses the Earth's atmosphere's filtering system (Rayleigh scattering) and is perceived blue by our vision.

Cigarettes: the European Union has 142 million smokers

The European Commission is planning to ban smoking in beaches.

European Commissioner Vytenis Andriukaitis urged countries to make all public spaces smoke-free, including beaches, parks, sports facilities, but also cars with children.

Currently, only seven European countries have a complete ban on smoking in enclosed public places. They are Bulgaria, Greece, Hungary, Ireland, Malta, Spain, and the United Kingdom.

Clouds: they are critical to the earth's balance | Photo: Shutterstock

Clouds play an important role in the climate system, and can warn us of what lies ahead. Learn how to identify cloud types.

Clouds provide shade, store water, and distribute heat from the equator to the poles. Their mechanisms are still not completely known, but their relevance to the earth's balance is unquestionable.

The World Meteorological Organization (WMO) created an International Cloud Atlas that recognizes ten types of cloud. Clouds can appear at between 6,500 feet (2,000 meters) and 16,500 feet (5,000 meters).

Acid drops can be dangerous, especially if you jump into shallow waters. But if you learn how to do it properly, they can be fun and look good in a video.

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