2006-12-12 11:38:07 · 7 answers · asked by jenn 1 in Science & Mathematics ➔ Earth Sciences & Geology
Air pressure is the weight of the air directly above a given point. Since the atmosphere is fairly even at its top (where it meets space), the higher you are, the less atmosphere is on top of you, so the less it weighs.
2006-12-12 11:41:41 · answer #1 · answered by Dave 2 · 1⤊ 0⤋
Air is a fluid. Think of our atmosphere as an ocean of air on top of the world's land and water and we are the fish swimming around in that ocean of air. The top or surface of the air is called the stratosphere. Just like the water ocean, there are waves and currents in the air. When a big wave comes along, we call that a high pressure area and when a dip comes along we call that a low pressure area. Troughs occur just like in the ocean.
Since we are bottom dwellers, except when we take an aircraft or rocket ride, we measure the weight of the air sitting on top of us and call that an atmosphere.
The weight of all that air is really not very much, about 14 pounds per square inch or around 29 inches of mercury. Mercury was used early on because it was heavy enough to keep the tube short and accurate because its weight never changes. Recently, some folks have gone to measuring it in millibars, which is a metric measurement just so people can think they are being anti-American.
Of course, the atmosphere is NOT completely like water since it is so much lighter. When a big wave comes along, it is usually cooler than the lower pressure air and the difference in temperature makes for some interesting fireworks such as lightning.
If you look at a pressure gauge for a car's oil system or just about anything else, it will go to zero. If the air really weighs 14 pounds per square inch then why isn't it displayed on the pressure gauges? Because, both sides of the gauge are open to atmospheric pressure and the two sides cancel each other out. There are special gauges that do NOT do this. They measure ABSOLUTE pressure and are called absolute pressure gauges. Barometers are absolute pressure gauges with no way to connect a hose to it. A little different device is called an altimeter for measuring altitude, does the same thing, it just displays the information differently and is adjustable for airport heights above sea level. I guess I got a little windy didn't I? Pun intended.
2006-12-12 12:07:33 · answer #2 · answered by plezurgui 6 · 1⤊ 0⤋
i ) As already mentioned in other posts, Earth's atmosphere contains oxygen. It is worth noting that it also contain nitrogen and carbon dioxide. 2 ) Mercury is for all practical purposes a world without an atmosphere, although it does have out-gassing. 3) Mars does have a very thin atmosphere of CO2. Although, at the equator in the summer the temperature is about 70 F that only extends to about an inch. Above that, you freeze. 4 ) Pluto may have an atmosphere??? But there is no real hard data to go on.
2016-05-23 16:12:04 · answer #3 · answered by Anonymous · 0⤊ 0⤋
the air it may look like nothing smell like nothing but it does have a weight...so the lower(altitude) u are on earth the hevier the air is...that is pressure...the air is pressing on you...the higher u get the pressure is lower ,cuz is not as much air over u...also air pressure varies by weather...heat, cold, etc...
2006-12-12 11:47:19 · answer #4 · answered by Johnny B 2 · 0⤊ 1⤋
air pressure depends where there is more altitude
the higher the altitude the more air pressure
2006-12-12 11:42:06 · answer #5 · answered by ¡ RocH oN iCe ! 2 · 1⤊ 0⤋
Different temperatures
2006-12-12 11:39:41 · answer #6 · answered by Allen L 4 · 0⤊ 2⤋
various temperatures and elevation from sea level.
2006-12-12 11:40:26 · answer #7 · answered by afghaniguy007 2 · 0⤊ 1⤋