text: why is trapped air a good insulator? science homework alright, to answer this question, i'm going to have to make sure you know a few things.  1)  a substance is a solid, liquid or gas depending on how close or far apart the atoms in the substance are.  in solids, the atoms are much more tightly packed.  2)  "heat" is the total amount of kinetic energy on an atomic level.  3)  heat can only transfer when two atoms (or, for that matter, molecules) interact.  now picture the following scenario:  you enter a very crowded room.  you're pushing and shoving like crazy.  because the room is so crowded, even people on the other side of the room are going to have to start moving to compensate for your boorish behavior.  or  you enter a very nearly empty room.  you're still pushing about.  but because it's not at all crowded, you only affect the people who are nearby.  the people on the other side of the room just stare at you funny.  the people in the room are the molecules of the substance you are trying to transfer heat into.  you are the extra kinetic energy, the heat, entering the system.  you can only transfer energy into something you're able to come into contact with.  in a gas, the heat doesn't have the opportunity to affect the distant molecules.  this is why, when boiling water, the pot gets really hot, the water takes a longer time to get hot, and the air above the water is still cool enough to touch.  hope this is helpful.