Airplane wings are shaped to make air move faster over the top of the wing. When air moves faster, the pressure of the air decreases. So the pressure on the top of the wing is less than the pressure on the bottom of the wing.

Several physical and physiological factors decrease when we fly due to the unique environment of a pressurized cabin at high altitude. Most notably, air pressure decreases; even though the cabin is pressurized, it usually mimics an altitude of 6,000 to 8,000 feet, which leads to a decrease in blood oxygen saturation (hypoxia). This often causes fatigue or mild lightheadedness. Humidity also plummeted in older aircraft to below 10% (drier than the Sahara Desert), leading to rapid dehydration and a decrease in the sensitivity of our taste buds, specifically for sweet and salty flavors—which is why airplane food often tastes bland. Furthermore, the low pressure causes gases in the body to expand, which can paradoxically lead to a decrease in comfort as bloating increases. On a mechanical level, as the aircraft burns through thousands of gallons of jet fuel, its total weight decreases significantly throughout the flight, allowing it to climb to higher, more efficient altitudes. Finally, your "perceived time" might decrease or shift depending on your direction of travel, but the most immediate physical change you will feel is the drying out of your skin and eyes due to the extreme lack of moisture in the recycled air.