Why is the sky blue? From all the colors possible, why blue? Why not red or purple? Well to start, the sun emits white light, this white light contains all of the colors in the [spectrum] rainbow; yellow, red, orange, green, blue, purple. This is why sometimes after it rains, the rain droplets divide the light into all those colors and form a rainbow, during that stage the sky technically has all the colors. So why is it blue most of the time? Well, every color has a wavelength, like the piece of a puzzle that fits perfectly and makes a specific color separate from the white light when it comes into contact with something, ignoring all the other colors. Every object that has color works with this special feature; sunflowers have a yellow fit, your hair has a fit and grass has a green fit. As you might -or might not- now the sky is made from gases, technically air. The sky is a giant mass of air and the air up in the sky has a special fit too, blue. So when this white light comes down at us from the sun to the surface of the earth, it encounters these gases in the sky, and all of the colors are ignored but blue, which fits like the piece of a puzzle.
Language is a limited tool because reality is not concise nor universal, so language is constrained by preceding knowledge. The more extensive the previous knowledge is, the wider the range of language one can use; the narrower the previous knowledge, the more limited language is, and the greater the effort required to explain the idea. Explaining a topic in which you own bast understanding to a person that has none-to-little idea of what it is about is an example of the limitation of language. If your intention is for the person to grasp the concept of what you are talking about, then you must avoid using terminologies that are exclusive to the topic and find a more adequate vocabulary. Usually, the better the contextual familiarity there is between two or more persons the better the understanding with fewer explanations and less restricted use of language.
When I had to explain why the sky was blue to a kid who probably had no previous knowledge about it, I had to lean towards their perspective while maintaining the original idea I was trying to communicate. I also avoided the use of words like “spectrum “or “atmosphere” and substituted them with others like “rainbow” and “giant mass of air”. I also used analogies like the color’s wavelengths being similar to the pieces of a puzzle that only “fit” with a certain something to bring out the color. That is probably not the most scientifically accurate explanation, but it properly communicated the idea to someone that had little knowledge on the topic – or I would hope so. Although from the perspective of a real specialist in the topic my knowledge would be seen as faint. And if they were to explain to me more, they too would have to constraint the language they use.