Wow, this sounds like DD3. There have been several times I've looked out the window and said, "Oh, it's raining outside," and she'll insist it's not raining. My favorite is when she tells me the sky isn't blue after I've commented on how nice and blue the sky is on any given day. I told my mother she's going to be a lawyer.
Hehe ... okay the sky is blue comment I just can't resist this one. The famous question "Why is the sky blue?" has my standard answer of it isn't blue. Technically it is all colors absorb with the blue shade reflected back. (And yes this works on all objects) so when your daughter is arguing that it isn't blue she is correct. <evil grin>