why does a window get foggy when you breathe on it on a cold day but not on a warm day?

Dear student,
The window gets foggy when we breathe on it in a cold day but not on a warm day because the air that we exhale has water vapour or moisture in it. When we breathe on a window that is cold due to cold day, the water vapour condense on the window and form water droplets, thus performing the process of condensation.This process is just same as glass of cold liquid which has water droplets outside the surface as atmosphere has water vapour or moisture in it.
Regards 

  • 1
What are you looking for?