When leaving the house, on a rainy day, the driver first tries to turn on the car window wiper so that he can see, even if there is a little difficulty.
However, the window cleaner is not enough to allow a good vision for the driver, as the windows fog up and are no longer a transparent surface, becoming a translucent surface.
Translucent surfaces do not allow us to have a coherent view of what lies behind them, allowing us a partial view.
But what does this change in the car window entail? Why does this happen on rainy days?
The answers to these questions are simple. On rainy days, the temperature inside the car is usually higher than outside; the water molecules that are vaporized inside the car are condensed due to the difference in temperature.
When the molecules of vaporized water (gaseous state) are condensed (liquid) they aggregate to the glass, making it translucent, as the surface becomes irregular.
There are ways to prevent this from happening: turn on the defogger, turn on the air conditioning and use a cloth to gradually dry the glass inside, so that it does not interfere with the direction.
by Frederico Borges
Graduated in Physics
Brazil School Team
Source: Brazil School - https://brasilescola.uol.com.br/curiosidades/por-que-os-vidros-dos-carros-embacam-dias-chuvosos.htm