The main factors affecting the condition and direction of the winds are as follows:
1. Pressure/Barometric Gradient
2. The Motion of the Earth’s Rotation
3. The Physical Features.
1. Barometric Gradient: Between any two places, the difference between air pressure is called ‘Pressure/Barometric Gradient. This gradient is in horizontal direction. Pressure gradient is also called barometric slope. Wind speeds are high when there is more pressure gradient between any two places, but on the contrary, the speed of the wind is slow when the pressure gradient decreases.
2. Earth’s rotational speed (The Motion of the Earth’s Rotation): Due to the motion of the earth’s rotation, the winds are deflected. This is called the Coriolis force and the effect of this force is called the Coriolis Effect. Due to this effect, the winds are deflected towards their right side in the northern hemisphere and towards their left side in the southern hemisphere. This effect was proved by a scientist called Ferrel, so it is also called Ferrel’s Law.
3. Physical Features: The terrestrial inequalities on the Earth inhibit the path of the winds, which affects the direction and speed of the winds. The amount of friction on a relatively flat ocean surface is low, causing the wind to flow at a much faster pace. On the contrary, the volume of friction is higher on the plate boundaries, which causes the speed of the winds to slow down.
This is the reason that due to the oceanic expansion in the southern hemisphere, the Westerlies winds flow faster and in a fixed direction. However, due to the terrestrial parts in the Northern Hemisphere, the speed of the Westerlies winds becomes relatively slow.