Key Parameters

  • Positive vorticity advection (PVA):
    • The enhanced cloudiness lies in the left exit region and has superimposed upon it a fairly strong maximum of PVA at 300 hPa.
  • Shear vorticity at 300 hPa:
    • The cloud field of the Front Intensification by Jet Crossing lies at the cyclonic side of the zero line of the shear vorticity at 300 hPa, which indicates the jet axis.
  • Isotachs:
    • The increased cloudiness lies within the left exit region of a well developed jet streak.
  • Thermal front parameter (TFP):
    • The thermal front parameter indicating the Cold Front, and the zero line of the shear vorticity indicating the jet axis, form an acute angle, sometimes nearly perpendicular.
12 August 2005/12.00 UTC - Meteosat 8 IR 10.8 image; red: positive vorticity advection (PVA) 300 hPa, yellow: isotachs 300 hPa