Originally Posted by
spectastic
what's the difference between an air pad and an insulated inflatable pad? is it thickness? how thick does an air pad have to be to considered "insulated?"
You can look up the difference yourself in more detail on these them Interwebs.
It's not the thickness. Basically, the air pad has no insulation inside, while the insulated pad does. It thus drastically reduces convective heat losses and is much more effective in preventing your body from losing heat to ground.
The air pad will feel great at the beginning, and them the air inside would start moving and transporting your body heat to its lowest layer, where it will cool down to ground temperature. In a few hours, your butt will feel cold. The air will also shrink while cooling down, resulting in a partially deflated pad, which further reduces its insulating capability. Even those air pads with internal coatings against heat loss via radiation suffer from the convective issue, I have plenty of experience with those.
I'm probably capable of writing a PhD dissertation on the subject, but it is best for you to acquire this sort of knowledge by yourself.