Huggy
I have just read the rest of this thread in detail and I am afraid you are also incorrect in your interpretation of the universal gas law:
If the volume is constant and the temperature drops then the pressure will DROP. i.e. with a constant volume pressure is directly proportional to temperature. That is why aerosol cans explode when heated etc...
Anyway this relationship cannot simply be applied to the atmosphere because for most calculations the volume cannot be considered constant and density has to be considered.
USUALLY when the temperature drops density will increase and pressure will increase as a result
i.e. the increase in pressure you refer to is due to the increase in density rather then the reduction in temperature
Max