Question

When you step inside a warm ski lodge on a cold day, you find your glasses fog. why does this occur?

Answer 1

Answer: Condensation of moisture in the air onto the glasses.

Step-by-step explanation:
When you come from a cold environment into a warm ski lodge, the glasses are at a much lower temperature than that of the lodge.
Because the air in the room contains moisture (water vapor), it condenses on a surface whose temperature is lower than the dew point of the room.