Sorry b, gonna need to know that the observations are.
Answer:
Air pressure is the weight of air molecules.
Explanation:
Air pressure can be described as the force generated by the weight of air on the surface of the Earth. The size and number of the air molecules determine the air pressure.
When the number of molecules in the air increases, it generates more force on the Earth's surface and we say that it is regarded as a rise in the atmospheric pressure. A mercury barometer is a device which is used to measure the air pressure.
I believe the answer you're looking for is Evolution.
