No, I am not advertising for Lay’s chips. At the Grand Canyon you are at 6800 feet. It’s high enough for the pressure inside the bag to exceed the outside atmospheric pressure. So my model was kind enough to show you two bloated bags. It happens in jetliners too. The cabin is pressurized to about 6000 – 8000 ft. I never noticed the pressure change on an airplane but walking about at >6000 ft will leave you short of breath. Maybe. I was. Colleen wasn’t. She’s a better (wo)man than me. … and always has been.