[standardUser]

To this day I insist that American traffic lights are red, orange and green. I know what yellow looks like and that is not yellow, it is orange. As a child, I couldn't understand the concept of calling it yellow despite it emitting orange light. Now, I understand the concept of colloquially referring to things by incorrect names, but I still hate it.

[rrrrrrrrrrrryan]

The concept of "red = stop" and "yellow = slow" existed prior to electricity and artificial light: in rail transportation, a yellow flag meant proceed with caution.

When traffic lights were first created, they simply didn't have the technology to create a great pure yellow, so amber was used instead, and people understood the color they were aiming for.

[standardUser]

Makes sense, since Yield signs and similar warning signs are all yellow as well. But being born into a world where everyone calls an orange light yellow is confusing nonetheless!

[ztetranz]

In New Zealand the middle light is (or at least was) called amber.

Now I live in the US and the lights here look the same as NZ but I'm pretty badly colorblind so they're just words to me :)

Horizontal rather than vertical lights were new to me here. They make sense because they don't swing around in the wind.

[glandium]

In France, it's called orange.