why do outside plants tolerate higher temps?

[HempKat]

Ambient Co2 is around 350-400PPM. Most growers are using 1000-1500PPM inside.

I do not think it is CO2 because it would not be that hard to bring in enough Co2 to keep the room at 350-400

i was reading the links carl provided and it seems to make sense. It is a balance between temps and humidity that keeps the stomata open.

Basically the higher the temps, the higher the humidity should be.

Problem is keeping a bedroom at 80% humidity does wonders for the drywall.

You wouldn't want humidity that high indoors, anything above 65% is like asking for powdery mildew to form.