1. Density and Air pressure
Earth Science II
(Session 2)

2. Ciencias de la Tierra II
Introduction
There are physical factors that influence the atmosphere:
Density of the air
Pressure of the air
Temperature of the air
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Density
Air density: is the amount of molecules the air contains in a volume unit.
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Air density (gases) is reported in units of g/L.
The factors that affect air density are:
Temperature
Pressure
Water Vapor
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Pressure
Air pressure: is the force that air exerts in a certain area.
Pressure = Force / Area
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Air pressure (gases) is reported in units of g/cm2.
The factors that affect air presssure are:
Temperature
Density
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Pressure
More temperature more pressure (in a closed system like a balloon)
Increased temperatures in the atmosphere results in lower pressure. (hint…is heated air heavy or light?)
More Density results in more pressure
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Density
More temperature less density
More pressure more density
More molecular weight more density
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Atmospheric pressure increases when air density increases and altitude decreases.
So where is there more pressure, at the base of Mount Fuji or at the top?
Where is the air more dense, at the base or the top?
What are some things that happen to our bodies as we climb this mountain?
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Air Pressure
Let´s check out this website:
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Air Pressure
When we blow up a balloon …. Does it expand?
What is happening to the air pressure inside the balloon versus outside the baloon?
Why does it make a noise when it's popped?
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Answer…
The air pressure inside the balloon slowly becomes greater than the air pressure outside the balloon.
When the balloon is popped, the air escapes instantly.
The sound you hear is from the molecules of air inside the balloon coming into sudden contact with the molecules of air outside the balloon.
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Bibliography
DiSpezio, M. et al. (1999). Science Insights: Exploring Earth and Space. first ed. USA: Prentice Hall.
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