Question

Wearing many layers of cotton clothes keep you warmer than one thick sweater why?

Answer 1

Because many layers of cotton clothes trap a more amount of air in between them, as we know that air is a poor conductor of heat it do not allow the body's heat to go outside and as a result it keeps us warm.

Answer 2

this is because they trap cool air and make us warm.
During winter many opt for this dressing style in order to keep themselves warm from extreme cold