Final answer:
Atmospheric pressure decreases with increasing altitude due to the lower weight of the air column above and the temperature drops with height. This decrease can impact breathability and is a factor in altitude sickness.
Step-by-step explanation:
The decrease in atmospheric pressure as one moves upwards is primarily due to the diminishing weight of the air above. As altitude increases, the amount of air exerting pressure from above drops, resulting in lower atmospheric pressure. This is why on the summit of Mt. Everest, the air pressure is significantly less than at sea level. Additionally, the temperature of the atmosphere generally decreases with height at a rate known as the lapse rate. A cooler atmosphere means lower kinetic energy of air molecules, which contributes to a reduction in atmospheric pressure. It's also important to note that barometric pressure variations with altitude can impact health and activities. For example, lower pressure at high altitudes can cause altitude sickness, as the exchange of oxygen and carbon dioxide in the lungs becomes less efficient.