Dry convection

1
Dry convection
6

• Convective planforms in a dry convective boundary
  layer heated from below. Lengths are in units of
  the layer depth.
• Note the cellular structure with O(1) aspect
  ratio and a strong correlation between w and T
  (buoyancy) perturbations.

Moeng and Rotunno 1990
2
Lab Thermals (Scorer 1957 JFM)

• A small dense water mass is released near the top
  of a homogeneous water layer, making an
  upside-down thermal.

Time-sequence of snapshots of evolving
thermal (viewed upside-down for comparison with
clouds)
3
Shallow-Cu LES soundings presented with ????l, ?v

• Cumulus core updrafts have
• positive ?v (buoyancy)
• no ? (T excess)
• negative ?l (due to ql)

Siebesma et al. 2003 JAS
4

• Mean summertime central Pacific ITCZ soundings
  from the 1999 Kwajalein Experiment, presented
  using h and h.

Sobel et al. 2004
h
h
undilute buoyancy
lifted parcel h