2. Hot Dogs

When the windows are rolled up in a car on a hot day, why does it get stuffy and hot?

Once the windows are rolled up, the volume of air within the car stays the same. As long as the sun keeps shining, that air keeps getting warmer. Sunlight comes through the window glass and is absorbed by the interior. Outside, all the metal also absorbs the sun's heat.

The heat inside may radiate outside the car a bit, but not enough to cool things off much. A dog or other animals left inside a closed car in full sun can quickly become overheated (dogs do not sweat). This "hot dog" needs a cool drink of water and plenty of fresh air, fast!