Question for weather gurus

We've all heard of the infamous FS FOG LAYER - How can one enable it manually from within FSX?I tried setting visibility to 1/16, stratus from ground up, etc and altho I get reduced visibility I do NOT get the fog layer.I need to be able to turn it on and off for some testing.ThanxVicQ6600 G0 CPU 2.4 o/c 3.65Evga 680i A1 with P31 BIOS 2G XP2-8500 DDR2 1066FSB Mushkin 996535 RAM 5-5-4-12-2T320G 7200 HD partitioned for XP/Vista/Programs 2 - 74G Raptors in RAID0 500G 7200 HD for backup SATA DVD burner Evga 8800GTS 640 PCIx 169.13 betaKandalf LCS case w/ built in liquid cooling 850W Thermaltake power supplyVisit the Virtual Pilot's Centerwww.flightadventures.comhttp://www.hifisim.com/banners/hifi-supporter-sigbanner.jpg