Surface winds are influenced by friction with the Earth's terrain, altering their speed and direction, while upper-atmosphere geostrophic winds are unaffected by surface features and are shaped by the balance of pressure gradients and the Coriolis effect.
Friction layer winds, or surface winds, are affected by the surface features of the Earth, such as mountains, buildings, and vegetation. These obstacles contribute to friction which slows down the wind and causes it to change direction. On the other hand, upper-atmosphere geostrophic winds are free from the influence of the Earth's surface. These winds are governed by the balance between pressure gradient force and the Coriolis effect, leading to movement that is more parallel to isobars or lines of equal atmospheric pressure. This balance results in a smoother flow that is not directly influenced by the Earth's surface but by the imbalance in pressure and temperature and the Earth's rotation.
In the troposphere, which extends up to about 12 km above the Earth’s surface, the variation in surface friction across diverse terrains significantly impacts wind patterns. Geostrophic winds, being above this layer, do not experience the same level of friction and hence exhibit different characteristics compared to surface winds. In conclusion, the primary differences between friction layer winds and geostrophic winds are due to the influence of Earth's surface friction, which alters the speed and direction of winds closer to the ground.