I think it depends on the person and what is going on in their life at the time. A sunny day can make one feel positive but if you just learned your mother died sunshine is not going to put you in an upbeat mood. On the other hand a rainy day at home with the one you love watching old black & white movies by the fireplace can feel like the perfect romantic day.
Sunshine usually translates to happy or mellow moods. But when it starts getting cloudy and rainy you will find everyone is more moody or sleepy.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.