Reading the bubble
Shells: air warmer than normal for the date by 8, 14 and 20 K. The innermost is the hot core
Blue shells: 5 and 8 K colder than normal, the cold vortex core (key K)
Pale disc at 8 km: the tropopause
Trail: the +14 K shell one and two days earlier, as ghosts (key T)
box: 40–90° N, 0–32 km (1000–10 hPa) · height exaggerated