The sky was darker than usual. A strange tint of purple that is not all too noticeable at first. Perhaps if you concentrate closely, you will notice that the colour is gradually darkening over time. A gradual darkening from dark blue to purple to red.

A red sky? How odd.

After a moment or two the red starts fading away. From red to purple to dark blue. Had the sky really turned red? Or were your eyes playing tricks on you?