Osmosis passes from a medium with a high concentration of water molecules to another with a low concentration of water molecules and since the potato has low water concentration so the water transfers to it increasing its mass
Lymphedema is the condition I believe.
The one with higher air pressure is Warm Air. The reason why is because when you boil water, the water always makes the lid rise. This is because Warm Air has more activity in its atoms and molecules, so it is moving around more, which in turn means that there is more pressure.
Hope I helped. :)
B. tears , this is not a first line of defense