Rustling leaves...I like the idea of that. Its fairly difficult to come up with generic background noises that are calming at the same time. Leaves sound like a good bet though.
It has always seemed strange to me that some people find hostile weather sounds calming - Wind, heavy rain, thunder... those can all potentially damage the building you are in. Fire too (I like the sound of a fire only if I can see it.) Leaves would be a good addition though. So would a waterfall (there is a significant difference between a waterfall and rain.)
To be honest it never even occurred to me to classify it as "hostile".
I think its fairly dependent on the climate you grew up in. e.g. I'm from a fairly warm/dry climate so "storm" sounds mean rain & relief from heat. Plus the local farmers are much happier (except when there is hail involved).
>damage the building you are in
Again - never occurred to me. Its just a non-issue here. Buildings are built to last & we don't get natural disasters here.
I associate these sounds with the act of sheltering from these elements, which prevents all kinds of physical activities and encourages passive, calm ones. A tendency towards hibernation and hot chocolate by a fireplace, a calm and pleasant association. Even if I focus on the negative aspects -- getting caught out in the rain and being cold and wet, I generally bundle up and conserve my energy rather than start jogging... not positive, but still calm.
Sufficiently strong weather and uncontrolled fires could put you at risk, but the extremely vast majority of my experience with these sounds has been with the safe varieties -- I don't think I'd find it as calming otherwise.
