Why there is low pressure at high altitude?
 

why there is low pressure at high altitude?

Think of deep sea. The deeper you go, there is more water stacked on top of you pressing down. So, higher pressure at down deep sea, less pressure at top of water.
Although air is not heavy like water, but air has also weight. The higher you go the fewer air is above you.
So you get the same effect --> high pressure at sea level, low pressure at high altitude

Ref: [url=http://ph.answers.yahoo.com/question/index?qid=20110220050830AA58ywT]Yahoo! Answers - How come at high altitude ther is low pressure?[/url]

atmospheric pressure
 

In a mountain regions why food takes more time to cook ?

Pressure at high altitude
 

[QUOTE=Ali hassan abbasi;287420]why there is low pressure at high altitude?[/QUOTE]
Pressure which the air exert on us is equal to (hdg) whereas h is height of the air above us, g is acceleration due to gravity and d is density of air.As you go upward, h an g both decrease,so low pressure.

[QUOTE=Ali hassan abbasi;287650]In a mountain regions why food takes more time to cook ?[/QUOTE]
[B]Fact: [/B]The Temperature of any liquid cannot be increased beyond its boiling point.
[B]Consequence:[/B] Suppose any liquid starts boiling at 90 degree C, its temperature cannot be increased beyond that no matter how much heat (energy) you provide.

[B]Fact: [/B]Boiling point is the point at which vapor pressure (of the liquid) equals the atmospheric pressure.
[B]Consequence:[/B] Since atmospheric pressure is lower at higher altitudes, the corresponding vapor pressures can be reached at relatively low temperatures. (say for water at about 98 C instead of 100 C)

[B]Conclusion: [/B]Since at higher altitudes (lower atm. pressures), the boiling point is reduced, thus the food takes more time to cook.

center of Gravitational pull is deep inside the earth.
matter closer to earth experience more pull while matter away from it experience as low pull as it is away.
so
atomospheric pressure is also due to gravitational force on air and thus it keeps on decreasing as you go higher from sea level.

this is the reason behind it.

[B]Conclusion: [/B]Since at higher altitudes (lower atm. pressures), the boiling point is reduced, thus the food takes more time to cook.[/QUOTE]

I do not understand this point if the boiling point is reduced it should take less time not more ..... I am badly confused :(

[QUOTE=Ali hassan abbasi;432355][B]Conclusion: [/B]Since at higher altitudes (lower atm. pressures), the boiling point is reduced, thus the food takes more time to cook.
I do not understand this point if the boiling point is reduced it should take less time not more ..... I am badly confused :([/QUOTE]

Dear !

At high altitudes in presence of low atmospheric pressure it becomes hard enough to manage heat.
even if you successfully manage it, it can not heat the food with same force and intensity as it does on earth.
When the heat management is comparatively difficult it means it requires more time than what it takes on earth surface......
even more than the falling degrees of boiling point ...... :)

This is why the cooking is delayed at high altitudes.

[QUOTE=Ali hassan abbasi;287650]In a mountain regions why food takes more time to cook ?[/QUOTE]

the fire needs oxygen to burn up and as well know that on mountains or high altitudes there is less oxygen as compared to surface of Earth so that's the reason why food takes more time to get cooked on mountains...