Why do windows fog on cold days?
Show answer & explanation
Answer: Indoor humidity condenses
Indoor humidity condenses ✓ — Correct! Warm indoor air holds moisture. When it contacts cold window glass, water vapor condenses into droplets. This is why fogging is worse with poor insulation or high indoor humidity.
Glass sweats from inside — Wrong. Glass doesn't contain or release water. The moisture comes from humid indoor air.
Temperature cracks release moisture — Wrong. Temperature changes don't crack windows or release moisture. Condensation comes from humid air hitting cold glass.