Why does the water level of the glass not rise in this experiment?

Answer

Dear Koen,

When you turn the bottle over, a little water runs out, creating a negative pressure in the air phase at the very top (pressure is lower than atmospheric pressure). The difference in pressure between the water surface of the glass and the closed air phase then compensates for the hydrodynamic pressure of the weight of the water in the bottle.

This only works because the bottle is closed at the top. If you make a small hole in the top of the bottle, the bottle will drain.

It shows how great the air pressure is on Earth. A similar experiment is the tearing apart of the Magdeburg hemispheres.

Kind regards,

Philippe Tassin