Re: How do pizza boxes work???

There are three ways the pizza can get rid of its heat energy:  
conduction, convection or radiation.

Conduction is the process where heat energy travels from a hot object to a 
cooler object that the hot object is touching.  The only thing the pizza 
is touching is the bottom of the box.  It will increase the temperature of 
the bottom of the box to close to the temperature of the pizza.  However 
the bottom of the box has little mass so it cannot accept much of the 
energy from the pizza.  The bottom of the box can only conduct its newly 
acquired heat energy to the wave structure which has little area in 
contact with the bottom of the box.  So conduction there is limited.  As 
you know, the outer bottom of the box will be warm.  This is evidence that 
some conduction is taking place.  Conduction is driven by the difference 
in tempetature between the objects in contact.  So as each item becomes 
closer in temperature to the item it is in contact with, the amount of 
heat transfer decreases.

Radiation is the transmission of heat energy as pure energy through empty 
space.  This is how we receive most heat energy from the sun.  As you move 
your hand toward a hot object from the side, at some point you will feel 
the heat.  That is almost pure radiant heat.  Heat transfer by radiation 
is inefficient.  The top sides and bottom of the pizza box will receive 
radiant heat energy, but not much.

Convection is actually a variety of conduction.  The hot pizza touches the 
air molecules in the box and raises each molecules temperature.  As the 
collection of molecules next to the pizza get hot enough the volume of 
heated air expands, becomes lighter than the air above it and rises to the 
top of the box.  The hot molecules give some of their heat to the inner 
top of the box, and drop back down to the top of the pizza.  This transfer 
is limited by the small mass of the top of the box, the low volume of air, 
and the small area of contact between the wave structure and the upper and 
lower surfaces of the top of the box.

All of this heat transfer is further limited by the poor inherent heat 
conducting properties of paper.