What a difference a little sunshine makes. Just take a look at the pictures below. With only a few hours in between, they're both taken at the same spot.
It's ten o'clock in the morning when I take the first picture. It's overcast and misty.
I take the second picture at around three in the afternoon. The overcast is gone and thanks to the sunlight there's much more colour and contrast. The dim grey feeling the first picture arouses is gone. Instead, it's almost impossible not to be cheerful.