How and why are friction layer (surface) winds different from upper-atmosphere geostrophic winds?
a) Friction layer winds are influenced by surface obstacles, while geostrophic winds are unaffected by surface friction.
b) Friction layer winds move parallel to isobars, while geostrophic winds move perpendicular to isobars.
c) Friction layer winds are slower than geostrophic winds due to surface drag.
d) Friction layer winds exhibit more variability in direction compared to geostrophic winds.