What would you expect to cause a drop in air pressure?

Weather patterns are a common cause in barometric pressure drops. When low-pressure weather systems move in over a certain area, not only is pressure in the atmosphere shifted, but it causes the barometric pressure reading to drop. A low-pressure system indicates that low-pressure air rises and begins to cool Explanation:

the abdomen (less formally called the belly, stomach, tummy or midriff) constitutes the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. the region occupied by the abdomen is termed the abdominal cavity. the stomach secretes acid and enzymes that digest food. ridges of muscle tissue called rugae line the stomach. the stomach muscles contract periodically, churning food to enhance digestion. the pyloric sphincter is a muscular valve that opens to allow food to pass from the stomach to the small intestine.