What effect does altitude have on air pressure?
437723
Pressure increases as altitude increases. Also, underwater, when elevation decreases.
495221
Barometric pressure is the measure of how dense the air around you is. It is measured in inches or millibars.  The reason for this type of measurement is that early barometers were constructed using a tube of mercury.  it was discovered that a tube containing mercury sitting in a pool of mercury varied with the air pressure.  Scientists noted that this device gave a higher reading at the bottom of a mountain where the air is more dense than at the top where there is less air pressure to support that column of mercury.( if you could keep going higher you would get to a place where there is no air to support your column of mercury.  That is outer space. Say you took an inflated balloon with you on your journey to outer space.  It would explode because there are air molecules inside the balloon pushing outward, and no air pressure outside the balloon to keep it in check. The same with your body.). The average reading at sea level is around 30 inches of mercury.  If you live in a place where there are mountains you can test this for yourself. Most barometers now days do not use mercury, but instead are operated using a spring. Take your barometer with you when you travel up a mountain.  As you get higher you will see the reading decrease. As you travel up or down a mountain, your ears might "pop".  This is due to the change in air pressure. Have you noticed the weatherman talking about areas of low preassure and areas of high presure? The barometric pressure is what they are talking about.  In general the higher the air pressure the less likely there will be a storm. In tornados and hurricanes air pressure is very low. This lower air pressure is what causes some people with arthritus to complain of their aches and pains and causes your headaches. \nSandy Claws
1031939
temperature decreases with increase in altitude
1182741
This is due to two reasons:\n\nAt high altitude, the atmospheric pressure is much less than sea level, because gravity causes most of the atmosphere to settle towards the Earth.  In fact, over 50% of the atmosphere resides under the five mile mark above the Earth.  As a result, the air is less dense the higher you go.  \n\nNow it is true that the sun heats this air, but since there is less pressure, it expands as it rises much more easily than the air does near the Earth.  As a result of this expansion, the air cools.
107381
I agree, your English is poor but I think you are asking:\n\nWhen flying in aeroplane, how much pressure is outside? \n\nThe exact outside pressure will depend on the altitude at which you are flying. At a common cruising altitude of  37,000 feet, the outside air pressure is about 3.2 psi. At sea level it is 14.7 psi.  \n\nWhy does it sometimes shake?\n\nFlying in an airplane through air is just like riding in a car along a bumpy dirt road or a ship across choppy open water. The air, while invisible, is very much like an ocean and is always in motion while the aircraft moves through it. The more turbulent the air mass, the more the plane will bouce or shake as it passes through it. At high speeds the air takes on fluid like properties around an aircraft. The oceans are not always calm and glassy and neither is the air which is a constant mass in motion. Just like a journey on the seas or a country road, you cannot always expect your journey to be completely smooth.
928334
Are you talking about the positive end expiratory pressure (PEEP)? The mean airway pressure or the alveolar pressure in the lungs? All have slightly differing values. These are usually measured in mm Hg or cm H2O. All airway gas exchange is performed through passive diffusion in the aveoli of the lungs. Air must be at normal atmospheric pressure at 760 mmHg for most efficient gas exchange to occur. \nAir at higher altitudes has lower pressure, so one must work harder, in physiological terms to enable the diffusion of oxygen. usually for mountain climbers, this means increased rates of respiration. At high enough altitudes, you cannot get enough oxygen with respiratory effort and you pass out from hypoxia.\nAt higher pressures (underwater) gas diffusion occurs more quickly, and you must use less oxygen to get the same blood oxygenation level as you wold at sea level. This is why divers use a NOx mix, and not pure oxygen underwater, if they did, they would develop oxygen narcosis very quickly.
139400
the air gets thinner as you rise in elevation.  the thin mountain air doesn't trap the heat as well as the thick air near sea level does.
224344
it is true that at higher altitudes there is more heat provided by the sun, but there is also much less atmosphere between the surface of the earth and space.  This means that the thermal energy provided by the sun travels out to space much faster, causing a temperature drop.  In addition as previously mentioned, gasses at lower pressures tend to exist at lower temperatures as given by the ideal gas law.
417406
Cold falls, right! The higher you are in altitude, the colder it gets!
225537
At sea level, the pressure the air exerts downward is at 1 atmosphere (normally).  If you decend 32 feet below water, the water pressure acting on you is 1 atmosphere as well, even greater as you go deeper.\n\nWhen you try to suck air down underwater, the water is trying to push it back up.  At some point, you just wont have enough "sucking power" to over come the weight of the water.
564655
As you increase in altitude there is less atmosphere. Atmosphere includes the following gases... nitrogen, oxygen, water vapor, carbon dioxide, argon, methane, etc.\n\nNitrogen makes up the most of the atmospheric gases at roughly 78%. Since nitrogen is the majority of the gases, the light that reflects will be blue. Nitrogen absorbs all other colors except for blue so that is what we see.\n\nWhen you move up away from the earth, gravity has less of an effect on the gases. Most of the atmosphere is held closely to the earth. So as you go up, there is less air therefore less nitrogen. Less nitrogen means less scattering of blue light that you see.
820723
Atmospheric pressure is the pressure at any point in the Earth's atmosphere.\n\nIn most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above the measurement point. Low pressure areas have less atmospheric mass above their location, whereas high pressure areas have more atmospheric mass above their location. Similarly, as elevation increases there is less overlying atmospheric mass, so that pressure decreases with increasing elevation. A column of air 1 square inch in cross section, measured from sea level to the top of the atmosphere, would weigh approximately 14.7 lb. A 1 m² column of air would weigh about 100 kilonewtons.\n\nStandard atmosphere (symbol: atm) is a unit of pressure and is defined as being precisely equal to 101,325 Pa. This value is intended to represent the mean sea level pressure at the latitude of Paris, France, and as a practical matter, approximates the mean sea level pressure for many of the industrialized nations (those with latitudes similar to Paris). One standard atmosphere is standard pressure used for pneumatic fluid power (ISO R554), and in the aerospace (ISO 2533) and petroleum (ISO 5024) industries.\n\nIn 1982, the International Union of Pure and Applied Chemistry (IUPAC) recommended that for the purposes of specifying the physical properties of substances, “the standard pressure” should be defined as precisely 100 kPa (≈750.062 torr) rather than the 101.325 kPa value of “one standard atmosphere”.[1] This value is used as the standard pressure for the compressor and the pneumatic tool industries (ISO 2787).[2] (see also Standard temperature and pressure)\n\nIn the United States, compressed air flow is often measured in "standard cubic feet" per unit of time, where the "standard" means the equivalent quantity of air at standard temperature and pressure. However, this standard atmosphere is defined slightly differently: temperature = 68 °F (20 °C), air density = 0.075 lb/ft³ (1.20 kg/m³), altitude = sea level, and relative humidity = 0%. In the air conditioning industry, the standard is often temperature = 32 °F (0 °C) instead. For natural gas, the petroleum industry uses a standard temperature of 60 °F (15.6 °C).\n\nAtmospheric pressure is often measured with a mercury barometer, and a height of approximately 760 mm (30 inches) of mercury is often used to teach, make visible, and illustrate (and measure) atmospheric pressure. However, since mercury is not a substance that humans commonly come in contact with, water often provides a more intuitive way to conceptualize the amount of pressure in one atmosphere.\n\nOne atmosphere (101.325 kPa or 14.7 lbf/in²) is the amount of pressure that can lift water approximately 10.3 m (33.9 feet). Thus, a diver at a depth 10.3 meters under water in a fresh-water lake experiences a pressure of about 2 atmospheres (1 atm for the air and 1 atm for the water).\n\nIn terms of city water pressure, one atmosphere is approximately one-half to one-fifth the pressure of typical city water mains (i.e., water pressure is around 2 to 5 atmospheres).\n\nThe most common type of barometer used in homes is the aneroid barometer (Figure 3). Inside this instrument is a small, flexible metal capsule called an aneroid cell. In the construction of the device, a vacuum is created inside the capsule so that small changes in outside air pressure cause the capsule to expand or contract. The size of the aneroid cell is then calibrated and any change in its volume is transmitted by springs and levers to an indicating arm that points to the corresponding atmospheric pressure.
836671
At an atmosheric pressure of 101.3 KPa (14.7 psi), the usual pressure at sea-level (it DOES vary a bit with the weather), water boils at 212 deg.F or 100 deg.C.  However, the boiling point goes down as the atmospheric pressure goes down, which is what happens when you go up in elevation.  Where I live, the elevation is about 4600 ft.  In a physics lab I took here, one of the experiments was to measure the B.P. of water.  It turned out to be 92 deg.C.
19016
Can you be more specific?  The earth's atmosphere has many gases in it, one being oxygen.  Dry air and humid air will have little difference in oxygen levels.  Altitude, however, does affect oxygen.  The higher you are, the less air, and less oxygen.  I hope this helped.
677782
It's the change in air pressure which causes it.
1067371
May 29, 2000 -- Unfortunately, there's not much you can do to prevent this problem -- though there are ways you can ease its effects. It's a fact: Being at a high elevation is stressful to your body. The concentration of oxygen is 21% at both sea level and at higher altitudes, but the decreasing air pressure at higher elevations means you get significantly fewer oxygen molecules per breath once you go over about 8,000 feet. \n\nBefore your trip, make an effort to hit the gym more often, or do a few extra laps at the track. This can minimize the dizziness, fatigue, shortness of breath, nausea, and headaches that signal altitude sickness. Fitness at sea level doesn't guarantee an easier time when you're 2 miles high. But being in good shape makes it more likely that your lungs will be able to cope with the challenges of the high life. \n\nThere are also ways to ease the body's transition to higher altitudes once your trip begins. If you're going higher than 8,000 feet, take it slow. When you arrive, try to let your body acclimate for a day or two. When hiking up to 15,000 feet or more, spread out your ascent over a period of two or three days to give your body more time to adapt. And once on your trip, watch what you eat and drink. You'll want your respiratory system operating at full capacity, so avoid alcohol and any drugs that might interfere with your breathing, such as sleeping medications. \n\nIf your symptoms are severe, a prescription drug called Diamox may help. It works by stimulating your breathing, so that you take faster and deeper breaths. It can be taken on a plane several hours before arrival or at the airport before departure.
776651
Going to the mountains (higher Altitude) would lead to respiratory ALKALOSIS.  The reason for this is that there is less oxygen at higher altitudes and the oxygen hunger would lead to hyperventilation thus decreasing the co2 which raises the ph making the blood alkalotic