Why Bathroom Mirrors Fog Up After a Shower
Key vocabulary
- vapour noun — A gas made from a substance that is normally liquid.
- moisture noun — Small amounts of water in the air or a material.
- invisible adjective — Unable to be seen.
- condensation noun — The change from water vapour into liquid drops.
- airflow noun — The movement of air through a place.
Read the article
After a hot shower, the mirror can look foggy. You try to see your face, but the glass is cloudy. Why does this happen?
Warm air holds water vapour. We cannot see this gas, so it is usually invisible. A hot shower adds more moisture to the air. [3]
The mirror is often cooler than the air. When warm air meets the glass, some water forms small drops on its surface. [1]
This is called condensation. The drops spread over the mirror and scatter light. That makes the reflection hard to see. [2]
A cold drink can get wet on the outside in the same way. Windows may also fog up on cool days. [1]
You can wipe the glass to clear it for a while. Better airflow helps wet air leave the room.
A foggy mirror shows a process we see in many places. Water can change form when air and glass have different temperatures.
Discussion questions
- Where else have you seen condensation in daily life?
- Why might opening a window help clear a foggy mirror?
- What simple science ideas did you learn through everyday experiences?
- How do people in your home deal with damp rooms?
- Would you prefer a short explanation or a live demonstration of this effect? Why?
Sources
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