Pressure and depth
2 marks · NormalDescribe why the air pressure is less at the top of a mountain than at sea level.
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There is less air above the top of the mountain, so the weight of the air pressing down is smaller, resulting in a lower air pressure.
Must show: less atmosphere above at altitude, weight of air produces pressure
Also accept: At higher altitudes, less air above means lower pressure
Common mistakes: Not linking to the amount of air above
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Refers to less air/atmosphere above at the top.
B2 · 1 mark · Describes that pressure is caused by the weight of air above.
Worked solution
At the top of a mountain, there is less air above pushing down, so air pressure is lower than at sea level where there is more atmosphere above.