The correct option is 2 and 3 only.
Explanation
Atmospheric pressure is the weight of the column of air at any given place and time. The rate of change of pressure with respect to distance is the pressure gradient. This gradient exists both vertically (with altitude) and horizontally (across the Earth's surface).
Statement-wise Analysis:
- Statement 1 is Incorrect. The vertical pressure gradient force is actually much larger than the horizontal pressure gradient force. Pressure decreases rapidly with height in the lower atmosphere (approximately 1 mb for every 10 meters of ascent), whereas horizontal pressure differences are comparatively small and spread over large distances.
- Statement 2 is Correct. Despite the strong vertical pressure gradient force directed upwards, we do not experience strong vertical winds under normal conditions. This is because the upward vertical pressure gradient force is generally balanced by the nearly equal but opposite gravitational force acting downwards. This state of equilibrium is known as hydrostatic balance.
- Statement 3 is Correct. Atmospheric pressure varies horizontally from place to place at the same elevation due to differential heating and other factors. These horizontal pressure differences create a horizontal pressure gradient force, which acts as the primary driving force causing air to move from high-pressure areas to low-pressure areas, resulting in wind.
Key Takeaway:
While the vertical pressure gradient is significantly stronger than the horizontal gradient, it is nullified by gravity (hydrostatic balance). Consequently, it is the weaker horizontal pressure gradient that drives the primary motion of air (wind) across the Earth's surface.