Stratocumulus Regime Extremely shallow moist layer and extreme capping; no mechanism to remove the cap; large scale subsidence strengthens the cap

Trade Wind Regime Moist layer a little deeper, but very dry aloft; no mechanism to remove the cap.

Indo/Pacific Warm Pool Marginally conditionally unstable through depth of troposphere. LCL low. Warm moist sfc air can get above LCL and have slight buoyancy to great heights, deep clouds, but relatively weak updrafts.

Indo/Pacific Warm Pool Can’t generate large buoyancy—get weak vertical velocity Marginally conditionally unstable through depth of troposphere. LCL low. Warm moist sfc air can get above LCL and have slight buoyancy to great heights, deep clouds, but relatively weak updrafts.

Oceanic sounding: at Gan in AMIE Undiluted parcel

Jordan’s (1958) mean sounding for the West Indies West Pacific Similar to Plot from Montgomery et al. 2006

“Hot Tower” Hypothesis Riehl & Malkus 1958

What’s going on here? Theta-e is reduced by entrainment in low levels, but fusion heating restores it back to PBL values in upper troposphere The famous Riehl & Malkus “undilute hot tower” sounding, Undilute ascent—classical assumption

Global Lightning Occurrence Many deep Cb over tropical oceans have extensive glaciated anvils but do NOT exhibit lightning & thunder. Christian et al. 2002

Updrafts in 100’s of aircraft penetrations of convective updrafts Continental flights Ocean flights Why? T profiles? Entrainment? Zipser and Lutz 1994

West African Squall Line No cap whatsoever. Very unstable all levels. LCL and LFC are elevated because air dry at lower levels. Once air gets above LFC, it can have very large buoyancy, strong updrafts, graupel, hail, lightning.

Continental sounding: West African Squall Line Can generate huge T-Td large w at low-mid levels  super cooled water, graupel, lightning ~10° No cap whatsoever. Very unstable all levels. LCL and LFC are elevated because air dry at lower levels. Once air gets above LFC, it can have very large buoyancy, strong updrafts, graupel, hail, lightning.

Tornado Soundings

Oklahoma Severe Thunderstorm Extremely CU both above and below the cap. Cap is not so extreme that it can’t be removed by trough or front. Moderately moist aloft, so easily saturated.

Average Oklahoma Tornado Sounding Fawbush and Miller 1951

Development of an Oklahoma Tornado Sounding Cools Warms Lifting removes the negative area Moist Adiabat Newton 1963

Hurricane Soundings

Hurricane Erin (2001) Halverson et al.

Hurricane Soundings and Jordan Sounding Sheets 1969