Answers

1. The region of the atmosphere that is most nearly dry adiabatic is btwn ~900mb and just under 500mb.

2. the region of the atmosphere where potential temperature is most nearly constant w/ height is several meters right above the surface to just under 500mb.

3. These two layers are the same b/c the environmental lapse rate as we saw on the stuve diagram was most nearly if not exactly dry adiabatic btwn thos two layers, it pretty much followed (paralled) dry adibats up to just under 500mb.