1 / 6

du/dt>0

geopotential heights/geostrophic streamlines. V ag <0. z. V ag >0. LEFT. divergence. 300 hPa. y. convergence. du/dt<0. x. JET EXIT. JET ENTRANCE. du/dt>0. convergence. divergence. rising. sinking. RIGHT. thermally direct. thermally indirect. 900 hPa. V ag >0. sinking.

dinh
Download Presentation

du/dt>0

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. geopotential heights/geostrophic streamlines Vag<0 z Vag>0 LEFT divergence 300 hPa y convergence du/dt<0 x JET EXIT JET ENTRANCE du/dt>0 convergence divergence rising sinking RIGHT thermally direct thermally indirect 900 hPa Vag>0 sinking COOL SIDE OF JET Vag<0 rising WARM SIDE OF JET LOW LEVEL JET ENHANCEMENT/FORMATION

  2. Maintaining Thermal Wind Balance Assume that the height of the 1000 hPa surface is = 0 here (i.e., 500 hPa hgts are equivalent to the thickness field!) > 0 > 0 If the wind shear decreases, the temperature gradient should also decrease!

  3. How does it do this? CONV/sinking DIV/rising

  4. Thus two things happen in tandem here to ensure thermal wind balance: • Under the influence of the Coriolis force the southerly ageostrophic flow aloft will deflect eastward (i.e., in the direction of the zonal flow) – and the northerly ageostrophic below will deflect westward (against the westerly flow) thereby increasing the vertical wind shear! • 2. The jet entrance is marked by a thermally direct circulation (i.e., warm air rising, cold/sinking). This acts to weaken the temperature gradient.

  5. How does Holton simplify his discussion? • The vorticity advection is weak (or non-exstent) at the base of 500 hPatrof/ridge axes (eliminates boxed terms) • 2. Temperature advection is weak over a surface trof/ridge (eliminates circled terms)

More Related