Effects of ice particle size vertical inhomogeneity on the passive remote sensing of ice clouds
Ice multiplication in clouds: modeling new processes
Transcript of Ice multiplication in clouds: modeling new processes
![Page 1: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/1.jpg)
Ice multiplication in clouds: modeling new
processes VAUGHAN PHILLIPS
DEPT OF PHYSICAL GEOGRAPHY AND ECO. SCIENCE, LUND UNIVERSITY, 25 OCT 2017
Acknowledgements: E. WILLIAMS MIT, USA M. FORMENTON, I. KUDZOTSA Lund University, Sweden J. SUN University of Hawaii at Manoa, USA J.-I. YANO Meteo-France, France E. ILOTOVIZ, A. KHAIN Hebrew University of Jerusalem, Israel A. BANSEMER, S. TESSENDORF NCAR, USA A. DETWILER South Dakata School of Mines and Tech., USA.
![Page 2: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/2.jpg)
Outline
• Overview
• Theory of Microphysics of Ice-ice Collisions
– Breakup
• Numerical Simulations of Multiplication and Lightning
• Conclusions and Future Directions
![Page 3: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/3.jpg)
• Overview
![Page 4: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/4.jpg)
Daily observations of lightning and dust near Miami
![Page 5: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/5.jpg)
Problem: if lightning is due to charge separated
in ice-ice collisions, why the lack of correlation
to dust, a key ice nucleus (IN) ?
![Page 6: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/6.jpg)
Ice multiplication seen in aircraft data
• Discrepancy between
active ice nuclei and
ice concentrations, if
cloud is precipitating
IE ratio = ratio of total to primary ice concentrations
field observations of many deep Cu (Hobbs et al. 1980)
![Page 7: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/7.jpg)
H-M PROCESS OF RIME-SPLINTERING
SHATTERING DURING RAINDROP-FREEZING
MECHANICAL FRAGMENTATION IN ICE-ICE COLLISIONS
-3 to -8 oC, humidity near water saturation
0 to -35 oC, humidity near water saturation
any sub-zero temperature, any humidity (water saturation previously)
ICE PRECIPITATIO
N
SUPERCOOLED RAINDROP
ICE PRECIPITATION
ICE PARTICLE
![Page 8: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/8.jpg)
H-M PROCESS OF RIME-SPLINTERING
SHATTERING DURING RAINDROP-FREEZING
MECHANICAL FRAGMENTATION IN ICE-ICE COLLISIONS
-3 to -8 oC, humidity near water saturation
0 to -35 oC, humidity near water saturation
any sub-zero temperature, any humidity (water saturation previously)
ICE PRECIPITATIO
N
FREEZING RAINDROP ICE
PRECIPITATION
ICE PARTICLE
![Page 9: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/9.jpg)
H-M PROCESS OF RIME-SPLINTERING
SHATTERING DURING RAINDROP-FREEZING
MECHANICAL FRAGMENTATION IN ICE-ICE COLLISIONS
-3 to -8 oC, humidity near water saturation
0 to -35 oC, humidity near water saturation
any sub-zero temperature, any humidity (water saturation previously)
ICE PRECIPITATIO
N
FREEZING RAINDROP ICE
PRECIPITATION
ICE PARTICLE
![Page 10: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/10.jpg)
H-M PROCESS OF RIME-SPLINTERING
SHATTERING DURING RAINDROP-FREEZING
MECHANICAL FRAGMENTATION IN ICE-ICE COLLISIONS
-3 to -8 oC, humidity near water saturation
0 to -35 oC, humidity near water saturation
any sub-zero temperature, any humidity (water saturation previously)
ICE PRECIPITATIO
N
FREEZING RAINDROP ICE
PRECIPITATION
ICE PARTICLE
![Page 11: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/11.jpg)
Approach: create formulations for aspects of ice-ice
collisions, such as fragmentation
- numerical modeling to explain lightning observations
![Page 12: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/12.jpg)
• Theory of Microphysics of Ice-ice Collisions
– Breakup
![Page 13: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/13.jpg)
New theory of fragmentation
• Conservation of energy for collision of 2 particles:
𝐾0
𝑐𝑜𝑙𝑙𝑖𝑠𝑖𝑜𝑛 𝑘𝑖𝑛𝑒𝑡𝑖𝑐 𝑒𝑛𝑒𝑟𝑔𝑦𝑏𝑒𝑓𝑜𝑟𝑒 𝑐𝑜𝑙𝑙𝑖𝑠𝑖𝑜𝑛
= 𝐾1 𝑓𝑖𝑛𝑎𝑙 𝑐𝑜𝑙𝑙𝑖𝑠𝑖𝑜𝑛
𝑘𝑖𝑛𝑒𝑡𝑖𝑐 𝑒𝑛𝑒𝑟𝑔𝑦
+ Δ𝑆 𝑤𝑜𝑟𝑘 𝑑𝑜𝑛𝑒𝑡𝑜 𝑠𝑒𝑝𝑎𝑟𝑎𝑡𝑒𝑝𝑎𝑟𝑡𝑖𝑐𝑙𝑒𝑠
+ 𝐾𝑡ℎ
𝑒𝑛𝑒𝑟𝑔𝑦 𝑙𝑜𝑠𝑡 𝑎𝑠 ℎ𝑒𝑎𝑡𝑎𝑛𝑑 𝑛𝑜𝑖𝑠𝑒
𝑊𝑐𝑟𝑖𝑡 = work done to break a branch of length, w
PDFs of 𝑊𝑐𝑟𝑖𝑡 or 𝑤 ≈ 𝑐3𝑊𝑐𝑟𝑖𝑡𝛾
𝑔 ∝ 𝑊𝑐𝑟𝑖𝑡𝛾−1exp −
𝑊𝑐𝑟𝑖𝑡𝑊0
𝛾
𝑝 𝑤 = 𝜆 exp −𝜆𝑤
![Page 14: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/14.jpg)
New theory (cont.)
• A fraction, 𝑐2, of energy dissipated is available for
breaking branches, 𝛿𝐾𝑡ℎ = 𝑐2𝐾𝑡ℎ ≈ 𝑐2𝐾0 1 − 𝑞2 .
• Branches broken per collision:
𝑁 = 𝛼𝐴 𝑇, 𝐷, 𝜒 P 𝑊𝑐𝑟𝑖𝑡 ≤𝛿𝐾𝑡ℎ𝑁𝑐𝑜𝑛𝑡𝑎𝑐𝑡
= 𝛼𝐴 𝑇, 𝐷, 𝜒 P 𝑤 ≤ 𝑤0
𝑁 ∝ 1 − exp −𝐵𝐾0
𝛼𝐴 𝑇,𝐷, 𝜒
𝛾
𝑤0 = 𝑐3𝛿𝐾𝑡ℎ𝑁𝑐𝑜𝑛𝑡𝑎𝑐𝑡
𝛾
= 𝑐3𝑐2𝐾0 1 − 𝑞
2
𝑁𝑐𝑜𝑛𝑡𝑎𝑐𝑡
𝛾
= 𝑐3𝑐2𝐾0 1 − 𝑞
2
𝑛𝑏𝑟𝑎𝑛𝑐ℎ𝛼𝑐1
𝛾
= 𝛽 𝑇, 𝐷, 𝜒𝐾𝑐𝛼
𝛾
![Page 15: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/15.jpg)
Formulation fitted to published observations of
breakup
(graupel-snow, graupel-graupel, hail-hail)
Phillips et al. (2017a, JAS)
![Page 16: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/16.jpg)
• Numerical Simulations of Multiplication and Lightning
![Page 17: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/17.jpg)
Transformation of hydrometeors in aerosol-cloud model:
snow-water collisions
Vapor growth
Graupel-water collisions
Ice crystal-water collisions
Snow
collisions
wet growth of graupel
Collisions (self)
Graupel/hail Snow-water collisions
Fragments (cloud-ice)
ice-ice-collisions
Aerosol species
Cloud-ice
Cloud-droplets
Rain
Phillips et al. (2007, 2009, 2014, 2015, 2017b JAS): Kudzotsa et al. (2016, QJRMS)
![Page 18: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/18.jpg)
Non-inductive charge separation:
Empirical formulae (Brooks et al. 1997; Saunders and Peck 1998): RAR = EW x Vg sign of charge transferred, when compared with RARcrit (T) Charge transferred per ice-ice collision: Q = B da Vb q (Keith and Saunders 1989)
GRAUPEL Vg (Dg)
ICE d
![Page 19: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/19.jpg)
Model validation for STEPS (US High
Plains, summer 2000): aerosol-cloud
model and HUCM
![Page 20: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/20.jpg)
Cold-based convection near
Kansas/Colorado border, summer 2000
![Page 21: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/21.jpg)
Phillips et al. (2017b, JAS)
![Page 22: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/22.jpg)
Role of breakup
![Page 23: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/23.jpg)
![Page 24: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/24.jpg)
Budget: initiation of ice in aerosol-
cloud model
Phillips et al. (2017b, JAS)
![Page 25: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/25.jpg)
![Page 26: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/26.jpg)
![Page 27: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/27.jpg)
![Page 28: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/28.jpg)
![Page 29: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/29.jpg)
•
• Conclusions and Future Directions
![Page 30: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/30.jpg)
Summary
• Theories created for breakup
– Reproduces published lab data successfully
• Only with breakup represented can aircraft observations be
predicted correctly
• Explosive multiplication by breakup in snow-graupel collisions
produces most crystals, unless top of cloud is colder than -36 oC
– Graupel, snow and cloud-ice altered
– Breakup boosts lightning, especially intra-cloud (IC) lightning
![Page 31: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/31.jpg)
![Page 32: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/32.jpg)
![Page 33: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/33.jpg)
![Page 34: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/34.jpg)
Role of sticking efficiency
![Page 35: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/35.jpg)
![Page 36: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/36.jpg)
Mechanical fragmentation in hail-hail collisions
studied by Takahashi et al. (1995)
![Page 37: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/37.jpg)
Phillips et al. (2008, 2013, JAS)
Phillips heterogeneous ice nucleation scheme
(‘empirical parameterization’) based on coincident
field observations of aerosol and ice nuclei (IN)
PBAP IN Dust ice nuclei (IN)
![Page 38: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/38.jpg)
Measurement problems for aircraft
observations of clouds (Korolev et al. 2011)
![Page 39: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/39.jpg)
Yet lab studies show evidence of ice
multiplication by fragmentation
• Irrespective of whether aircraft observations of IE ratio
are reliable, cloud models must represent the
fragmentation observed in the laboratory if they are to be
accurate...
• Challenge: only a few lab studies have been done about
each multiplication process
• Solution: for any fragmentation process, create a theory
and fit it to the data from published experiments ...
![Page 40: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/40.jpg)
EP ice nucleation scheme validated off-line for
thin wave-clouds near -30 oC observed by aircraft
Phillips et al. (2008, 2013)
![Page 41: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/41.jpg)
• History of studies of multiplication
![Page 42: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/42.jpg)
Ice multiplication
• Rime-splintering (Hallett-Mossop 1974) requires droplets > 24 um
between -3 and -8 degC, so is absent in some (e.g. polar) clouds
• Raindrop-freezing only generates a few splinters per drop
• However, mechanical fragmentation may occur:-
– Lab experiments by Vardiman (1978) with crystals impacting a
plate:-
![Page 43: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/43.jpg)
Aircraft observations of Arctic polar clouds
(Schwarzenboeck 2009):
• 80% of all analysed crystals were fragmented,
• Of these fragmented ones:- – over 20% were naturally fragmented,
either mechanically or during sublimation in ice-only cloud
– up to 80% may have been artificially fragmented on impact with the probe or plane
![Page 44: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/44.jpg)
Shattering during raindrop-freezing:
Washington mixed-phase stratiform cloud
(Rangno 2008)
![Page 45: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/45.jpg)
Mechanical fragmentation in graupel-graupel
collisions studied by Takahashi et al. (1995)
![Page 46: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/46.jpg)
primary ice generation rate = constant
i g G c0
tf=
10min
tg=
30min
ti=
15min
Mechanical break-up in ice+ice collisions ~ a
ice crystal (i), small graupel (g), large graupel (G)
~
Organisation of ice multiplication by dynamics in 0-D analytical model
Yano and Phillips
(2011, JAS)
Increase with
vertical
velocity
![Page 47: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/47.jpg)
relaxation model analysis :
![Page 48: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/48.jpg)
saturation
-1% supersaturation
lag model analysis : water-vapor depletetion (Korolev and Mazin 2007):
Ice Enhancement Ratio: IE = ni/ni*
![Page 49: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/49.jpg)
• New theory of fragmentation
![Page 50: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/50.jpg)
Fit theory to experimental data
![Page 51: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/51.jpg)
• Full simulations of cold-based convective storm
– Role of fragmentation and explosive multiplication
![Page 52: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/52.jpg)
Transformation of hydrometeors in aerosol-cloud model:
snow-water collisions
Vapor growth
Graupel-water collisions
Ice crystal-water collisions
Snow
collisions
wet growth of graupel
Collisions (self)
Graupel/hail Snow-water collisions
Fragments (cloud-ice)
ice-ice-collisions
Aerosol species
Cloud-ice
Cloud-droplets
Rain
![Page 53: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/53.jpg)
Phillips et al. (2008, 2013, JAS)
Phillips heterogeneous ice nucleation scheme
(‘empirical parameterization’) based on coincident
field observations of aerosol and ice nuclei (IN)
PBAP IN Dust ice nuclei (IN)
![Page 54: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/54.jpg)
Phillips heterogeneous ice nucleation scheme
implemented in leading weather forecasting model
of USA (‘WRF’, NCAR):
![Page 55: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/55.jpg)
Cold-based convection near
Kansas/Colorado border, summer 2000
Phillips et al. (2007, 2009, 2014, 2015 JAS): Kudzotsa et al. (2016)
![Page 56: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/56.jpg)
Initialise with observed loadings of
aerosol species
![Page 57: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/57.jpg)
![Page 58: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/58.jpg)
![Page 59: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/59.jpg)
![Page 60: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/60.jpg)
![Page 61: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/61.jpg)
Ascent and radar reflectivity
![Page 62: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/62.jpg)
Budget: initiation of ice in aerosol-
cloud model
![Page 63: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/63.jpg)
Budget: initiation of ice in aerosol-
cloud model
![Page 64: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/64.jpg)
Ice concentrations
![Page 65: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/65.jpg)
• Conclusions and future directions
![Page 66: Ice multiplication in clouds: modeling new processes](https://reader031.fdocuments.net/reader031/viewer/2022012113/61dcbc3be48a584c447032b2/html5/thumbnails/66.jpg)
Summary
• Explosive multiplication produces most of the crystals in
the storm, unless the top of the cloud gets above the -36
degC level.
• Full modeling support for the 0D analytical theory of
multiplication
• Need to treat mechanical fragmentation if fundamental
questions about cloud interactions with aerosol, radation
and lightning are to be tackled.