Air pressure at sea levels is higher than at the top of mountain because the air at sea level

Air pressure at sea level is higher than at the top of a mountain because the air at sea level has a greater weight. Air has mass and weight, and the weight of the air above us exerts pressure on the surface of the earth. At sea level, the air above us extends all the way to the surface of the ocean, which means that there is a greater weight of air pressing down on us. As we move up a mountain, there is less air above us, so the weight of the air and the air pressure decreases. This is why people often experience difficulty breathing at high altitudes where the air pressure is lower. Therefore, the answer is that air at sea level has a greater weight.