Post-tropical Cyclone John - Air Mass at 18.5°N - 103.5°W

Key for AirMass RGB:

1 - Jet stream / potential vorticity (PV) / deformation zones / dry upper level (dark red / orange)

2 - Cold air mass (dark blue/purple)

3 - Warm air mass (green)

4 - Warm air mass, less moisture (olive/dark orange)

5 - High thick cloud (white)

6 - Mid level cloud (tan/salmon)

7 - Low level cloud (green, dark blue)

8 - Limb effects (purple/blue)

Air Mass RGB is used to diagnose the environment surrounding synoptic systems by enhancing temperature and moisture characteristics of airmasses. Cyclogenesis can be inferred by the identification of warm, dry, ozone-rich descending stratospheric air associated with jet streams and potential vorticity (PV) anomalies. The RGB can be used to validate the location of PV anomalies in model data. Additionally, this RGB can distinguish between polar and tropical airmasses, especially along upper-level frontal boundaries and identify high-, mid-, and low-level clouds.

• For more details, see the Air Mass RGB Guide, (PDF, 1.1 MB)