Why is there a difference in wind direction at 5,000 feet AGL compared to the surface wind?

The difference in wind direction at 5,000 feet AGL compared to the surface wind is primarily influenced by friction between the wind and the surface. Near the ground, wind interacts with various surface features such as buildings, trees, and terrain, which creates turbulence and slows down the wind velocity. This friction causes the wind direction to shift, typically causing it to veer towards a more aligned flow with isobars as altitude increases.

As you climb higher into the atmosphere, such as at 5,000 feet AGL, the influence of surface friction diminishes significantly. The wind at that altitude is less affected by obstacles, allowing it to follow more closely the pressure gradients indicated by the weather patterns. Consequently, the wind at higher altitudes generally blows more parallel to the isobars compared to the surface winds, which are influenced by the frictional drag. This results in a noticeable difference in wind direction between the two altitudes.

The other factors mentioned, such as pressure gradients, Coriolis force, and temperature differences, do play roles in wind behavior but do not directly cause the specific differences in wind direction observed between the surface and higher altitudes as friction does.