Seriously, I love Silent Hill's fog atmosphere. Sometimes at night in LA you'll get everything covered in thick fog like in SH but by the morning it's gone. Rarely are there times where fog like that lasts throughout the day.
Wouldn't it be fun and more calm if fog simply enshrouded the world like that 24/7 with some helpings of rain? I personally also enjoy fog because it openly conveys the world's true, evil nature. Moreso than rain.