Why does air pressure decrease with increasing altitude?
a) The weight of the air above is smaller
b) The weight of the air below is smaller
c) Less air above pushes down
d) There is more air below to push up more strongly
e) Colder air is less dense
f)Hot air rises
pressure is force/area
force is equal to weight, so
(a)
The correct answer is a) The weight of the air above is smaller.
To understand why air pressure decreases with increasing altitude, we need to consider the concept of atmospheric pressure. Atmospheric pressure is the force per unit area exerted on a surface by the weight of the atmosphere above that surface.
As you go higher in the atmosphere, there is less air above you, so the weight of the air pushing down on you decreases. This leads to a decrease in the atmospheric pressure.
One way to visualize this is to imagine a column of air extending from the surface of the Earth to the top of the atmosphere. The weight of all the air in that column creates the atmospheric pressure at the surface. As you go higher up that column, there is less air above you to contribute to the weight and hence less pressure.
Therefore, option a) The weight of the air above is smaller, accurately explains why air pressure decreases with increasing altitude.