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Cloud Microphysics
Jamin Hörni and Maurice Huguenin-Virchaux
13.12.2014 1
Thunderstorm Electricity
Jamin Hörni and Maurice Huguenin-Virchaux
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Two types of charge distribution structure:
Tripole or Dipole
Upper layer (above -20°C) particles carry
positive charges.
Lower/middle layer (-10 till -20°C) particles
carry negative charges.
If tripole: near cloudbase exists a small
positive center.
13.12.2014Jamin Hörni and Maurice Huguenin-Virchaux 2
Electric charge distribution I
Fig. 14.5 from Wang (2013)
A schematic of the charge distribution in a thundercloud. Dashed
contours are isotherms in °C. Thick solid contours are the graupel/hail
mixing ratio, whereas thin solid contours are rain mixing ratio.
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Electric charge distribution II
High electric field in charge centers.
Environmental electric field 100-300V/m
Electron avalanche
Füllekrug, M., Mareev, E. A., & Rycroft, M. J. (2006). Sprites, Elves and
Intense Lightning Discharges. Dordrecht, The Netherlands: Dordrecht :
Springer.
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balance of charges: fair weather vs. lightning
4 types of discharges
cloud-to-ground flash
intra-cloud flash
inter-cloud flash
cloud-to-space flash
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Lightning and Thunder Processes
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Cloud-to-Ground Flash
Stepped leader
v ≈ 105 m/s
Streamer
Return stroke
v ≈ 108 m/s
T ≤ 20’000 K
Dart leader and
second return stroke
Fig. 14.6 Wang, 2013.
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Intra-/Inter-cloud Flashes
http://ffden2.phys.uaf.edu/211_fall2010.web.dir/Levi_Cowan/lightning.html
Intra-Cloud:
In the same cloud, discharge between upper
(positive) and lower (negative) charge
centers
Sheet lightning
Inter-Cloud:
Electric field > breakdown requirment
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TLE = Transient Luminous Event
Blue Jet: blue, trumpet, 18-40 km upward
motion
Red Sprite: Different forms, 70-40 km
downward motion
Red Elves: donut shape, 85-100 km
spreading
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Upper Atmospheric Lightning
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Thunder
13.12.2014Jamin Hörni and Maurice Huguenin-Virchaux 8
observational study to the right
peak acoustic energy around 200 Hz
Distance to Lightning [km]:
# 𝑠𝑒𝑐𝑜𝑛𝑑𝑠 𝑏𝑒𝑡𝑤𝑒𝑒𝑛 𝑇ℎ𝑢𝑛𝑑𝑒𝑟 𝑎𝑛𝑑 𝐿𝑖𝑔ℎ𝑡𝑛𝑖𝑛𝑔
3 Wang,
2013.
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Thunder in popular culture
Chinese: Lei Gong
http://w
ww
.art
-and-a
rcha
eolo
gy.
com
/
Japanese: Raijinhttp://characters.cultural-china.com/
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Thunder in popular culture
http://wikipedia.org
Greek: Zeus
Phidias at 435 BC
Seven Wonders of the Ancient World
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Thunder in popular culture
http://r
esourc
es2.n
ew
s.c
om
.au
Norse: Thor
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Titlepage: Swiss Lightning: http://clikhear.palmbeachpost.com/wp-content/uploads/2012/08/24swisslightning.jpg
Fig. 14.6 & 14.7 from Wang, 2013.
Chinese Thunder God: http://characters.cultural-china.com/82hz164.html
Japanese Thunder God: http://www.art-and-archaeology.com/japan/s058.jpg
Statue of Zeus at Olympia: https://en.wikipedia.org/wiki/Statue_of_Zeus_at_Olympia#/media/File:Statue_of_Zeus.jpg
Thor the Dark World: http://resources2.news.com.au/images/2013/11/01/1226751/386994-thor-the-dark-world.jpg
13.12.2014Jamin Hörni and Maurice Huguenin-Virchaux 12
References
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Thank you!
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