# Jet Position

### The position of the jet streaks

For a Norwegian cyclone, divergence aloft is produced by the jet cross circulation in the left front quadrant of a jet exit region. This region is usually marked by a maximum in cyclonic vorticity advection (PVA max).

Due to the low-index circulation pattern, typical for Norwegian cyclones, the two jet streaks are aligned at an approximately acute angle to each other (see Figure 1).

Figure 1: Schematic of the position of the jet streaks for a Norwegian cyclone

For a Shapiro-Keyser cyclone, divergence aloft is produced by both the right rear quadrant of a jet entrance and the left front quadrant of a jet exit region (see Figure 2). Shapiro-Keyser cyclones seem to favor coupled jets (see Figure 3), a structure that is commonly found in rapid cyclogenesis situations.

Figure 2: Schematic of coupling jet streaks

Figure 3: Schematic of the position of the jet streaks for a Shapiro-Keyser cyclone