why does the empty bottle get squeezed when you left it overnight on the mountain?

Question

no, but i didn't bring the bottle down the mountain.

Answer 1

the air inside cools down and contracts

Answer 2

It's colder at night than during the day. Hot air expands and cool air contracts.

As you go higher in elevation, the air gets thinner, and pressure is lower. So if you had opened the bottle on the mountain and closed there, then the higher pressure from the bottom of the mountain will squeeze the bottle when you bring it back down.

Answer 3

Because of the pressure difference. That happens when you open and close it under a low pressure, (Typically in the mountains or on an aeroplane) and then take to it to a place with a higher pressure. (Typically at a lower height)
What happens is that when you first open it, the air stored in it will have a low pressure, which means there will be less molecules in it than if you had been at a lower altitude. When take it down, because of the higher pressure, the air in the bottle will be compressed, and the bottle will get squeezed.

Answer 4

The pressure inside is not enough to oppose the pressure outside specially on higher grounds. In every action, there must be an opposite and equal reaction.

Answer 5

This is true only in some cases - There are cases when up above the mountains you may find hot air or somtimes colder ones...

Answer 6

air pressure