* Sunlight is made of all colors: White sunlight is actually a mixture of all colors of the rainbow, each with a different wavelength.
* Short wavelengths scatter more: When sunlight enters the Earth's atmosphere, it interacts with the molecules in the air (mostly nitrogen and oxygen). These molecules scatter the light, but they scatter shorter wavelengths (blue and violet) much more strongly than longer wavelengths (red and orange).
* Blue light reaches our eyes: Because blue light is scattered more, it is scattered in all directions, including towards our eyes. This is why we see a blue sky.
Why not violet? While violet light is scattered even more than blue, our eyes are more sensitive to blue light.
Other factors:
* Time of day: The sky appears bluer at midday because the sunlight has to travel through less atmosphere. Near sunrise and sunset, the sunlight travels through more atmosphere, and the longer wavelengths (red and orange) are scattered more, making the sky appear red or orange.
* Clouds: Clouds can block the sunlight and make the sky appear white or grey.
Let me know if you have any other questions!
