6. Geostrophic wind and gradient wind

Question 1

Definition of pressure gradient (force)

Answer 1

Pressure differential between high and low pressure that makes air move perpendicular to isobars from high to low pressure

Question 2

Coriolis effect on moving air

Answer 2

Air starts moving from pressure gradient, coriolis force turns air to the right (northern hemisphere) and accelerates until PGF and coriolis force are equal and opposing and air flows parallel to isobars

Question 3

Buys Ballot Law

Answer 3

Northern Hemisphere hemisphere, back to the wind = low pressure on left, high pressure on right

Question 4

Geostrophic winds higher or lower at higher altitudes? (same isobar spacing = same pressure gradient force)

Answer 4

Higher

Question 5

Geostrophic winds higher or lower at lower latitudes (same isobar spacing = same pressure gradient force)

Answer 5

Higher

Question 6

Geostrophic wind - high around high, low around low, why?

Answer 6

Geostrophic wind rotating around high pressure: pressure gradient force and centrifugal force add up resulting in higher coriolis force and greater windspeed for same isobar spacing (around low, centrifugal force subtracts from pgf = lower speed for same isobar spacing)

Question 7

Geostrophic wind, gradient wind (definition)

Answer 7

Geostrophic wind = wind flowing parallel to isobars (pgf and coriolis force in balance)
Gradient wind = geostrophic wind modified by centrifugal force (circular around lows / highs)