Which atmospheric force counterbalances the horizontal pressure gradient?

The atmospheric force that counterbalances the horizontal pressure gradient is the Coriolis force. This force arises due to the rotation of the Earth and affects the movement of air masses. As air moves from areas of high pressure to areas of low pressure, the Coriolis force alters the direction of that movement, causing it to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

This deflection helps create geostrophic balance, where the pressure gradient force and the Coriolis force are in equilibrium. This balance allows for the establishment of wind patterns and influences weather systems, playing a crucial role in the dynamics of the atmosphere.

The other forces mentioned—gravitational, thermal, and frictional—play important roles in atmospheric dynamics but do not specifically counterbalance the pressure gradient in the same manner as the Coriolis force does. Gravitational force acts downward and is responsible for weight, thermal forces relate to temperature differences, and frictional force can affect wind speed near the Earth's surface but does not counteract the pressure gradient like the Coriolis force.