Class number 4/27 Jan 31, 2011 Buoyancy & parcel
processes.
Loose ends from last class:
5 contributions to parcel buoyancy by moisture.
Consider 4 parcels rising through the troposphere:
- dry air - cools by ~100K
- with 10 g/kg of moisture: effects
- Virtual effect of vapor: Tv = T(1+0.61q) ~ +2K worth
of lightness at surface
- Latent heat of condensation: L/Cp ~ +25K by upper
troposphere
- Latent heat of freezing: Lf/L ~1/8 of above (~
+3K)
- Heat capacity of vapor: adds ~2% to Cp, at low
levels (while vapor lasts in parcel).
- effect decreases with height, and Γm is pretty
small at low levels, so a small effect.
- Heat capacity of condensed water: adds ~4% to Cp, at
upper levels (where condenste exists)
- for reversible ascent (extreme!!), up to 3K since Γm
~ Γd = 10K/km at high levels
- Net effects, pseudoadiabatic vs. reversible:
- Mapes
QJRMS
2001 or just see its Fig.
5
here
Today's material:
Briefing
from Marcela
More about buoyancy and thermodynamics
Some microphysical and mixing
effects on parcel buoyancy -- can compute in HW1 Wiki
Entropy-based thermo for deep convection: I learned it from Raymond and Blyth 1991 (pdf)
Poor man's pseudo-buoyancy (parcel T
excess) in s-h-h* diagrams
ppt comparing MSE, entropy,
potential temperatures (from past homeworks)
From buoyancy to vertical momentum dynamics: book stuff (links repeated
from
class 2 & 3)
Cumulus clouds powerpoint
How to invert (entropy, qv, p) to get density (for buoyancy):
HOMEWORK Wiki
Wyoming
soundings site - skewT or text files
Open questions, assignments, and
loose
ends for next class:
Do
it
on
the
Wiki!
Testable questions about today's
material:
Do
it
in
the
Wiki!
