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19 Cards in this Set
- Front
- Back
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Name three real forces on the atmosphere.
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pressure gradient force, frictional force, gravitational force
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The horizontal gradient operator can be defined as
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a vector perpendicular to contours, directed toward higher values with a magnitude of ∂( )/∂n
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Friction
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collective effects of momentum exchanges at all scales
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Planetary Boundary Layer (PBL)
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the lower 1 km by surface...?(more in chap. 9)
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For large scale flows, frictional force is a function of ______ ______ in the vertical.
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shear stress
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Shear stress acts (along/opposite) the wind vector
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opposite
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Equations of motion in the horizontal direction rely on what forces? (3)
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pgf, coriolis, frictional
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Geostrophic wind is _____ to height contours, and is equal to Vg=1/f(k x (grad)Φ), but comes in what two other forms?
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parallel
component and natural |
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Cyclonic flow is CCW in the N hem, and CW in the S around a(high/low)
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Low
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Anti cyclonic flow around a high, is (CCW/CW) in the N hem, and (CCW/CW) in the S hem
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N:CW
S:CCW |
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The greater the pgf, the (greater/smaller) the geostrophic wind, and the force must be balanced by...
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greater
Coriolis |
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Departures from geostrophic wind occurs...
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near surface where friction is important, at highly curved isobars/contours, and with ageostrophic flow
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Effects of friction acting opposite the flow are
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reduced wind speed, reduced Coriolis due to low velocity flow, angle of wind vectors from highs to lows
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Since frictional force will decrease as we move away from the surface, what happens?
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ψ will decrease upward, there will be clockwise rotation of wind vector with height, and there will be veering through the PBL
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Gradient winds occur where?
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in regions with large curvature geopotential contours (or isobars)
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Examples of gradient winds can be found in
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ridges (supergeostrophic) or troughs (subgeostrophic)
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Characteristics of troughs are...
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force is in same direction as coriolis, velocity must decrease
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Characteristics of ridges are...
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force is opposite coriolis, same direction as pgf, and velocity increases so coriolis can counter centrifugal force
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True or False. Sharply curved troughs with steep pressure
gradients are often observed in the atmosphere, but ridges with tight pressure gradient and sharp curvature are never seen. |
True
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