Question

Atmospheric pressure decreases mainly due to
(A) Increase in the temperature of the air
(B) Increase in the moisture of the air
(C) Both
(D) None

Answer 1

Hint:We are going to recall the gas law, which states that the pressure is proportional to the density times the temperature of the air and after applying this concept we can arrive at the right answer.

Complete step by step answer:
An atmospheric pressure exerts due to molecular collisions of air molecules. When the bundles of air pockets move in the atmosphere, they undergo collisions with each other. As they collide with each other or on any surrounding object, a force is exerted on the object. Since the pressure is equal to applied force per unit area, this force results in
atmospheric pressure.The atmospheric pressures depend on the temperature and the density of the air. According to the gas law, the pressure is proportional to the density of the air times the temperature of the air.
Therefore,
\[P = \rho T\]
Here, \[\rho \] is the density and T is the temperature.
Therefore, the density of the air,
\[\rho = \dfrac{P}{T}\]
The density of the air is the population of the air molecules in the given area. The density of the air does not change.If the temperature of the air increases, the atmospheric pressure must decrease in order to keep the density of the air constant.Thus, the atmospheric pressure decreases due to increase in the air temperature.The density of the air depends on the moisture of the air, since water vapor has less density than the dry air pocket.As we know, the pressure is proportional to the density of the air, the atmospheric pressure decreases due to the increase in the moisture content of the air.
So, the correct answer is option (C).

Note: According to gas law, the pressure is proportional to the temperature that doesn’t mean an increase in the temperature of the air increases the air pressure. To keep the density constant, the atmospheric pressure decreases with the increase in the temperature of the air.