By putting these sunshades in the windows of a car, one can considerably negate the interior heating effect. What is the physics behind this?
I searched for it online but couldn't find a thorough and comprehensive answer. One thing which I got to know that visible light enters through the windows ( without these shades) and is absorbed by the interior of the car. This is given off as infrared light which can't pass back through the windows making the interior of the car very hot.