MTEOR 411/511 WEEK 3 SUPPORTING MATERIAL

Week 3 - Divergence, vorticity and deformation

All wind fields can be defined to potentially possess some of these quantities. Both divergence and vorticity are used to infer upward motion. Divergence can be used to compute vertical velocities, and it measures the rate of expansion or contraction of an air parcel. Vorticity measures the spin, and can be defined as relative vorticity (spin due to the winds) or absolute vorticity (wind spin plus spin of the earth). Areas of cyclonic vorticity advection aloft may be associated with rising motion while anticyclonic advection may lead to sinking motion. Deformation is often the forgotten stepchild, and plays a big role in frontogenesis.

• Discussion of kinematics (Leeds College, UK)
• Vorticity tutorial (PSU)
  

  Examine the following map to see what the winds are doing in regions of convergence/divergence. Is confluence always associated with convergence?

• Current (moisture) Divergence

  Examine the following map to see what terms are contributing to regions of large vorticity. Do you see cyclonic flow or horizontal wind shear in these regions?

• Current vorticity at 500 mb