Changes to BMJ shallow convection (2 of 4)

• Raise shallow cloud top in moist conditions (all points) if:

  • Mean in-cloud relative humidity (RH) > RHcrit
    • RHcrit => lifting the ambient temperature and pressure at cloud base 25 mb to reach saturation
    • RHcrit ~ 90% in typical conditions (e.g., 88.8% @ 900 hPa, 20°C)
  • CAPE > 0 (relax more stringent criterion of positive buoyancy [B>0] at all levels)
  • As before, tops cannot extend above 450 hPa