BGLOB.DAT
This file is only used by tactical saves.
Always two bytes, describes ambient light on map.
First byte indicates overall level of ambient lighting. On night missions it is 10h, on day missions 00h, dusk and dawn uses values in the middle. Second byte is ambient lighting of shadowed areas (below and inside Skyranger, inside UFOs), usually it is first byte+4. On the end of turn TERMP.DAT is recalculated using appropriate value from BGLOB.DAT as maximum. What determines which value of two is used is not known yet.