PDE Q36

Atmospheric pressure is caused by the gravitational pull of the Earth on the air molecules in the atmosphere. Gravity pulls the air toward the surface, and the weight of this air exerts pressure on everything below it, including the ground and oceans.

• Option A: rotation of earth
  Incorrect. Earth's rotation affects wind patterns and Coriolis effect but not the cause of atmospheric pressure.

• Option B: revolution of earth
  Incorrect. The Earth's revolution around the Sun does not affect atmospheric pressure directly.

• Option C: gravitational pull
  Correct. Gravity holds the atmosphere around the Earth and causes the air to exert pressure on the surface.

• Option D: uneven heating of the earth
  Incorrect. Uneven heating causes wind and pressure variations, but not atmospheric pressure itself.