How do we know about the hydrometeors in clouds? (hydrometeors: particles primarily made of water or ice. A precipitation product, such as rain, snow, fog, or clouds, formed from the condensation of water vapor in the atmosphere.)

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How do we know about the hydrometeors in
clouds?(hydrometeors particles primarily made
of water or ice. A precipitation product, such as
rain, snow, fog, or clouds, formed from the
condensation of water vapor in the atmosphere.)
Cloud microphysics instruments A brief
introduction.
(Cloud microphysics Characterization of the
number, size, morphology, origin, life-cycle, and
transformation of hydrometeors in fog and clouds.)
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Most basic remote sensing tools
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Geometrical Optics Interpret Most Atmospheric
Optics from Raindrops and lawn sprinklers (from
Wallace and Hobbs CH4)
Primary Rainbow Angle Angle of Minimum
Deviation (turning point) for rays incident with
2 chords in raindrops. Secondary Rainbow Angle
Angle of Minimum Deviation (turning point) for
rays incident with 3 chords in raindrops.
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Hello Halo.
Use your digital camera to document interesting
optical events in the atmosphere such as this
halo, or interesting clouds, or to document
measurements. Become famous -- the ATMS student
chapter of the American Meteorological Society
needs photos for a calendar project.
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Geometrical Optics Interpret Most Atmospheric
Optics from Ice Crystals (from Wallace and Hobbs
CH4)
22 deg and 45 deg Halos from cirrus crystals of
the column or rosette (combinations of columns)
types. Both are angle of deviation phenomena
like the rainbow. Crystal orientation important.
22 deg halo, more common, thumb rule to measure
size of arc.
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AWE some website for explaining Halos
Click here http//www.atoptics.co.uk/halo/circ1.h
tm
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Fuselage mounted instruments (out the window of
the aircraft).
Replicator
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CONTINUOUS HYDROMETOR REPLICATOR
P. B. MacCready, C. J. Todd, 1964. Continuous
Particle Sampler. Journal of Applied
Meteorology. Volume 3, pgs 450-460.
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WATER DROPLETS AND REPLICATORS
P. A. Spyers-Duran, R. R. Braham, 1967. An
airborne continuous cloud particle replicator.
Journal of Applied Meteorology. Volume 6, pgs
1108-1113.
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WATER DROPLETS AND REPLICATORS
P. B. MacCready, C. J. Todd, 1964. Continuous
Particle Sampler. Journal of Applied
Meteorology. Volume 3, pgs 450-460.
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CIRRUS ICE CRYSTAL REPLICATOR DATA
Arnott, W. P., Y. Y. Dong, J. Hallett, and M. R.
Poellot, 1994 Role of small ice crystals in
radiative properties of cirrus A case study,
FIRE II, 22 November 1991. J. Geo. Res. D1,
99 , 1371-1381.
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Balloon Borne Ice Crystal Replicator
The balloon-borne replicator collects and
preserves ice crystals and cloud droplets using
the Formvar replication technique. Details of the
instrument design and measurement capabilities
are described in Miloshevich and Heymsfield
(1997, J. Atmos. Oc. Tech., 14,
753). http//www.mmm.ucar.edu/science/cirrus/docs
/replsum.html
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Balloon Born Replicator Data
See this link for more on this case
study. http//www.mmm.ucar.edu/science/cirrus/proj
ects/FIRE/25Nov/25Nov.html
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Electro-optical Probe (2DC, 2 dimensional, cloud
probe)
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Pod mounted instrument for measuring
hydrometeors and particles in the atmosphere,
Meteorological Aircraft. Clink links below.
cloudscope
fssp
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Trade-offs with instruments that do more or less
the same thing an example.
Cloud microphysics probes for ice crystal
quantification 2DC Electrooptical probe
Fast response time, easy to analyze data, digital
data, aircraft pod mounted location so it doesnt
disturb the flow so much. ---- low resolution,
hard to see crystals. Replicator Probe ---- Slow
response time, hard to analyze data - one
particle at a time, analog data, fuselage mounted
location so it does disturb the flow. Crystals
are smashed on aircraft version, but not on
balloon version. high resolution, easy to
see crystals.
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Cloud Particle Imager Schematic View

• The particle detection system (PDS) consists of
  two continuous-wave laser diodes with beams that
  are shaped into ribbons 2.4 mm wide and 0.5 mm
  thick. The intersection of the two PDS beams
  defines the sample volume of the instrument. The
  PDS performs two functions
• When a particle passes through the intersection
  of the two laser beams, the imaging laser is
  pulsed and an image of the particle is cast on
  the CCD of the digital camera.
• The PDS counts particles that are
  transit-time qualified and particle concentration
  is determined by dividing particle counts by the
  sample area times true airspeed.
• http//www.specinc.com/cpi_operation.htm

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Cloud Particle Imager

• DATA SYSTEM
• Computer does sensor-head control, data
  collection, and data display and recording. The
  data system has an extensive graphical user
  interface (GUI).
• Particle images are extracted in real time
  from the million-pixel digital camera and sent to
  the data system host processor for display and
  storage.
• A DSP controls functions in the sensor
  head, including setting PDS laser power,
  conditioning and digitizing PDS detector signals,
  setting imaging laser power, acquiring and
  digitizing housekeeping signals, and controlling
  heaters.
• From
• http//www.specinc.com/cpi_operation.htm

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Cloud Particle Imager and Others on Lear Aircraft
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CPI DATA SAMPLES from http//www.specinc.com/
Digital images of ice crystals observed by the
SPEC Cloud Particle Imager (CPI). All particles
less than 0.5 mm in length
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Comparison CPI with 2DC and Replicator
CPI Great images, no crystal shatter as
with the replicator. ---- Trigger is sensitive
to many things (crystal, voltage level, etc).
---- Data rate is not sufficient to capture
allparticles, so counting statistics are tricky.

• My RecommendationFor aircraft sampling of
  cirrus clouds, use the following
• FSSP to infer small crystal content (lt 50 um).
• Use the 2DC to count and size all other crystals.
• Use the CPI to image crystals at high resolution
  and as a second instrument for counting and
  sizing crystals.