Standard weather engine

In my quest to try and get rid of my violenty shimmering horizons as they are rendered in the far distance I discovered that on different days and ast different times, the weather is depicted differently. For example, yesterday (27th Feb) at 1300, there was an obvious "haze layer" in the far distance which "hid" the far horizon and shimmering mountains until they slowly came into view through the "haze". Today, same time set but the view is completely different.....I can again see the mountains actually being rendered and thus shimmering violenty as there is no "vail" of haze. Let me confirm I have not changed ANY wx, vis, draw or sight distances, merely changed the date in the "create a flight" window. The effect is clear to see by simply setting a/c up at SeaTac, slewing to 10000', looking at the horizon and then, still in slew mode, changing the date from 27th to 28th Feb.Know I knew FS changed the graphics due to the season and had different schemes for different times of day but what I've never heard of is FS changing the visual effects of the atmosphere depending on the date set in the "create flight". Is anyone able to tell me 1/ In what way in which FS acheives these different "schemes" depending on date selected and 2/ If you're able to manually edit this showhow so that the "scheme" I saw yesterday lunchtime can be made "default" thus erradicating my problem with the horizon? I know I could fly everywhere at 1300 on the 27th Feb but this is hardly practical when I wish to do long haul/evening/summer flights as the scheme changes as time progresses (ie set 1630 27th Feb and the horizon is once again visible)I would value and ideas but please don't tell me to lower the vis to something realistic! As mentioned in my other thread "moving mountains", setting the vis to a lower value just means that when the horizon does come into view, it exhibits the same behaviour. I'm still unsure if this is an issue to me or FS as a whole....if anyone would care to let me know if they experience it I would be most grateful!Many thanksSteve