Why does air pressure decrease with altitude? Ask Question. Asked 10 months ago. Active 10 months ago. Viewed 6k times. Improve this question. Ted Staggs Ted Staggs 1 1 silver badge 7 7 bronze badges. So is gravity, but you can have either one without the other.
Then have someone lie on top of you. Then someone on top of them. Repeat until you're buried under people. Why does the person at the bottom feel more squished than the person on top? My cats have been performing that experiment for years. I'm still waiting to read about their scientific conclusions. Add a comment.
Active Oldest Votes. Improve this answer. Sandejo Sandejo 4, 1 1 gold badge 16 16 silver badges 37 37 bronze badges. Clearly, atmospheric pressure is almost non-existent, which hints at the fact that the two are unrelated.
The bottom springs will be compressed more than the top ones, because the bottom ones carry the weight of the top ones but not vice versa. In this analogy, the compression of the spring is the same principle as the air pressure at a given altitude. So unless the building is sealed hermetically or near-hermetically , the air inside quickly reaches the same pressure as that outside.
More: en. Show 2 more comments. Community Bot 1. It increases exponentially with depth for an ideal isothermal atmosphere. The higher you go, the less atmosphere there is above you, the less it weighs, so the pressure diminishes. Arguments about compressibility affect the exact rate that pressure decreases with altitude, but are irrelevant to the fact that it does decrease.
Monopole Monopole 3, 3 3 gold badges 6 6 silver badges 28 28 bronze badges. It does, but again, that's not part of the reason. That is exactly the answer. Inversely, the height of a mountain approximately determines the pressure of the air on its summit. This general relationship usually works quite well; however, factors other than physical altitude, such as latitude, temperature, and weather also effect the air pressure and contribute to how you truly feel at a particular elevation.
Think in terms of how wind chill can be significantly different than the actual temperature. Latitude: Just like there is no uniform sea level, there is no uniform atmospheric pressure throughout the world. The lowest portion of Earth's atmosphere, the troposphere, is wider at the equator 10 mi than at the poles 5 mi. So the further north or south you go from the equator, the lower the air pressure will be at a given altitude.
Contrary to popular belief, this variation in the troposphere is only slightly attributable to the gravitational shifts at higher latitudes due to the Earth's rotation and shape. The lower air pressure is caused almost exclusively by the lower temperatures encountered at more northern and southern latitudes. Adam Helman, et al. This is an excellent paper and was the basis for all of my calculations.
Temperature: Since cold air is more dense than warm air, at low temperatures the entire atmosphere is compressed downwards. Therefore, a specified air pressure will lie at a lower altitude in a cold environment compared to a warmer one. Using Dr. I gathered historical average monthly temperature data from Wikipedia for towns near each mountain which served as the basis for the calculations and the results were surprising.
Note: the average monthly temperature data are rough approximations but the calculations are based on solid mathematical and physical principles. So the calculated pressure altitudes aren't absolutely accurate but should be accurate relative to one another. Click here for the spreadsheet with full data and calculations. Insights from the Graph: The first thing to note is that the pressure altitude on the summit of Everest is never as high as its physical altitude which is good for those of us who climb without supplemental oxygen.
In conjunction, the pressure altitude on the summit of K2 is almost the same as that on Everest in January and December but then it just barely drops out of the 8, meter 26, feet peak list in July. Skip to content. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Altitude , like elevation , is the distance above sea level. Areas are often considered "high-altitude" if they reach at least 2, meters 8, feet into the atmosphere.
The most high-altitude point on Earth is Mount Everest, in the Himalayan mountain range on the border of Nepal and the Chinese region of Tibet. Mount Everest is 8, meters 29, feet tall. The urban area of El Alto, Bolivia, is the most high-altitude city on Earth. All 1. Altitude is related to air pressure. In fact, aviators and mountaineer s can measure their altitude by measuring the air pressure around them.
This is called indicated altitude , and is measured by an instrument called an altimeter. As altitude rises, air pressure drops. In other words, if the indicated altitude is high, the air pressure is low. This happens for two reasons. The first reason is gravity. Earth's gravity pulls air as close to the surface as possible. The second reason is density. As altitude increases, the amount of gas molecule s in the air decrease s—the air becomes less dense than air nearer to sea level.
This is what meteorologist s and mountaineers mean by "thin air. High-altitude locations are usually much colder than areas closer to sea level. This is due to the low air pressure. Air expand s as it rises, and the fewer gas molecules—including nitrogen, oxygen, and carbon dioxide—have fewer chances to bump into each other.
The human body reacts to high altitudes. Decreased air pressure means that less oxygen is available for breathing. One normal effect of altitude is shortness of breath, since the lungs have to work harder to deliver oxygen to the bloodstream.
It can take days and even weeks for a body to adjust to high altitude and low air pressure. People who spend too much time in high-altitude locations risk more serious symptoms of altitude sickness. These may range from headaches and dizziness to much more serious consequence s, such as brain or lung damage. Above about 8, meters 26, feet , the human body cannot survive at all, and starts to shut down.
Mountaineers call this altitude the "death zone. To prevent severe altitude sickness, mountaineers bring supplemental extra supplies of oxygen and limit their time in the "death zone. Different regions have different air pressures, even at the same altitude.
Factors such as climate and humidity impact local air pressure. Air pressure also decreases around the pole s. For this reason, if Mount Everest was located in the U. In astronomy , altitude has a somewhat different meaning.
0コメント