vIf the earth were greatly reduced
in size while maintaining its shape, it would be smoother than a billiard ball.
(Earth radius = 6371 km; Everest = 8.850 km)
vNonetheless, mountains have a
large effect on weather. Why is this,
if they
are so insignificant in size?
vAnswer: the atmosphere, like the
mountains, is also shallow (scale height 8.5 km) so mountains are a
significant fraction of atmosphere’s depth.
vBut, this answer underestimates
mountain effect for two reasons:
vStability gives the atmosphere a
resistance to vertical displacements
vThe lower atmosphere is rich in
water vapor so that slight adiabatic ascent brings the air to saturation.
vExample: flow around a 500-m
mountain (<< 8.5 km) could include 1) broad horizontal excursions,
2) downslope windstorm on lee side, and 3) torrential orographic rain on
windward side.
(Smith, 1979)
