Anti-Condensation Cups?

[chief]

My friend told me about these cups at Jamba Juice that he saw that did not condense water on the outside when there was a very cold beverage inside.

Does anyone know how it works?

[tcburnett]

The cups have an inner and an outer surface separated by an air gap.

[TNTruth]

Or a vacuum gap, a la a thermos bottle.

[charizard]

Condensation forms on any cool surface. The water vapor in the (warmer) air turns back into a liquid just because it's now below the dew point for the atmospheric condition.

So the basic answer is that any sort of "anti-condensation" cup is highly insulated, so that the coolness of the beverage isn't transmitted to the surface of the cup. The insualtor could be air, or a vacuum, or some other insulating material.