[Orange (OP)]

Hello,
I was wondering why Earth's atmosphere has a whiter color near the horizon (on a clear, cloudless day)?

Thank you!

[Kryptid]

My guess is that it is because you are looking through a larger volume of air when you look towards the horizon than when you look straight up.

[Orange (OP)]

But with this explanation, the sky near the horizon would be supposed to be orange, red like at sunset and sunrise instead of white, right?

[Origin]

But with this explanation, the sky near the horizon would be supposed to be orange, red like at sunset and sunrise instead of white, right?

No, white or grey is the color you should see.

[Janus]

But with this explanation, the sky near the horizon would be supposed to be orange, red like at sunset and sunrise instead of white, right?

No,  You see orange during sunrises and sunset, because that is the direct light from the Sun which is scattered the least by passing through more atmosphere.
When you are looking at the sky near the horizon when the sun is high in the sky, you are seeing the scattered light.  All the colors are scattered to some degree, blue just the most. So when you are looking near the horizon, you are seeing light that has been scattered enough for you to see a more full range of frequencies.

[William Hardy]

The light coming from the horizon is far and has passed through so many scattering that it is white or light-Blue.

[Orange (OP)]

There is something that I am not sure I understand, from the observer's point of view there is obviously a greater thickness of atmosphere in the direction of the horizon, but the rays starting from the sun and going into the region near the horizon only travels a little longer in the atmosphere (enters the atmosphere at a slightly smaller angle than 90 degrees) than those which arrive directly above the head of the 'observer.

So this small change in angle at which the sun's rays enter the atmosphere is enough to cause the whitish color on the horizon? That's right?

[Petrochemicals]

Probably liquid water particles like clouds, the clear sky varies on its blue intensity from day to day. At the horizon you are staring into a lot of dense atmosphere.