Hey John, this is extremely useful. It is a difficult diagram to understand, but with this, i can understand it! Just one question On the diagram with the ELR on it, between 1000mb and 960mb or so, does the ELR follow the temperature lines (at 45 degrees) if this is so, then does the ELR stay at about 18C for the first 800mb, or is it actually warming up (as if you are reading the temperature vertically)? Hope that made sense. Daz