Bag of chips at high attitude?!

So this is what happens when you take a bag of chips at high attitude.

Bag of chips at high Attitude.

For frequent flyers, many must have seen the bag of chips expanding like the picture above. But why does this happen? The reason is, the bag of chips are packed at normal atmospheric pressure at 14.1 psi. But as you go higher, the atmospheric pressure drops (at the rate of ). Thus, the dense air inside the bag tends to normalize with the external pressure. In this process it acquires larger volume causing the bag of chip to expand.