A straw is in a glass of water. I then cover the top of the straw with my finger and lift the straw out of the water. The water stays in the straw. Is this correct????............ The water in the straw falls ever so little because gravity pulls it down. The air pressure above the straw decreases as a result, until the combination of that lowered pressure and the pressure of the water in the straw equal the atmospheric pressure. If I were to then cut the straw somewhere in the liquid region so now the straw was shorter, and so there was now less water than before... Would the water that remained in the straw be pushed up higher into the remaining segment of straw...in order to increase the air pressure above the water? So that the combination of the new air pressure inside the straw and the pressure of the decreased amount of water equalled the atmospheric pressure?