STAGE-ONE FREEZING of A WATER DROP

The ejection of micro-droplets from the surface of a freezing super-cooled water drop has been observed and photographed. The fragmentation of a freezing drop in the forms of splintering, shattering, or bursting has been known for some times. This newly observed phenomenon of the ejection of numerous micro-droplets, the duration of their ejection, and the electrical properties of these droplets, suggest a possible mechanism of charge generation in a thundercloud!

.FORMATION of AIR BUBBLES at the INTERFACE of ICE( in COLOR) and WATER(TOP BLACK AREA) on the SURFACE of the FREEZING DROP(1mm).

MICRO-DROPLETS (POSITIVE CHARGED) ARE GENERATED by

BUSTING the BUBBLES.

RAW MATERIAL for FORGING THUNDERBOLTS
NEW SCIENTIS and SCIENCE JOURNAL
VOL. 49, NO.734 14 JANUARY 1971

WATER DROP FREEZING: EJECTION of MICRO-DROPLETS
SCIENCE
vol 170, p 1395, 1970

Recent observations by Roger J. Cheng of the State University of New York reveal a fascinating new microscopic process which almost certainly has an important bearing on how thunderclouds become charged to their high voltages

(Science. vol 170, p 1395, 1970).

About 10 years ago Dr B. J. Mason, Director of the Meteorological Office (then at Imperial College, London), advanced a novel theory in which the charge separation depended, at the atomic level, on the greater mobility of the protons in water compared with that of the negative OH ions. His experiments confirmed that protons do, indeed, travel more readily towards the colder end of a piece of dry ice supporting a temperature gradient. He established that when a stream of supercooled water drop froze on being blown past a hailstone in a wind tunnel it burst, shattering with the ejection of positively charged ice splinters, and leaving the hailstone negatively charged. Gravity acting on the 'hailstone, and up-currents on the splinters, could then give realistic charging rates for a typical thundercloud with a net charge of 1000 coulombs.

Cheng's discovery is that a freezing supercooled drop can perform its own charge separation in an even neater fashion. Starting with drops of one mm diameter he cooled them until they began to freeze at about - 15°C. Using cinematography he observed that at this juncture, the drops began to spray out tiny droplets 1 to 20um in diameter, through the thin, forming ice shell. They fell on hit micro slide in large numbers for approximately 50 seconds until the drop was completely frozen.

With an electrometer probe, and also by electrostatic deflection methods, Cheng showed that the ejected droplets carry a net positive charge, while the frozen drop retains a net negative charge. However the droplets form-whether forced out through minute cracks in the ice shell in response to internal pressure, condensed from water sublimated from the drop, or as a result of small bursting air bubbles beneath the ice surface-the charge separation at the atomic level clearly occurs as in Mason's hypothesis. The outer surface of the drop is colder than its interior and, again, concentrates the positive charge.

The MICRO-WORLD in the THUNDERSTORM

A JOURNEY through MICROSCOPE

exploring

The UNSEEN SECRETS of the THUNDERSTORM

WATER DROP FREEZING:
EJECTION of MICRO-DROPLETS

SCIENCE vol 170, p 1395, 1970

ROGER J. CHENG-ASRC-SUNYA

Abstract. The ejection of micro droplets from the surface of a freezing super-cooled water drop has been observed and photographed. The fragmentation of a freezing drop in the forms of splintering, shattering, or bursting has been known for some time. This newly observed phenomenon of the ejection of numerous micro droplets, the duration of their ejection, and the electrical properties of these droplets suggest a possible mechanism of charge generation in thunderstorms.

A water drop 1 mm in diameter, placed on a micro slide, was super-cooled inside a temperature-controlled chamber located under a high-power microscope. The freezing of the drop was observed by the use of cinephotomicrographic techniques. The chamber and drop were cooled. At the moment the freezing started, a thin ice shell formed immediately on the surface of the water drop and its temperature, monitored by a small thermocouple, jumped to 0°C. Then a large number of small water droplets, ranging from < 1 to 20 um were ejected from the surface of the freezing drop. These droplets fell onto the microslide. The small droplets were ejected continuously for an average of 50 seconds, with the exact length of the ejection period dependent on environmental conditions. During this period the small droplets on the slide near the freezing drop grew more rapidly than the ones farther away. The concentration of small droplets on the micro-slide also increased rapidly, and the interior temperature of the freezing drop remained about 0°C.

After freezing was completed, the growth of the small droplets terminated and the temperature of the frozen drop decreased rapidly to the environmental temperature. Then all of the small droplets began to diminish in size. Those farthest from the frozen drop gradually disappeared. Some of the small droplets froze by contact with spicules from the frozen drop . Similar experiments were also performed with a water drop suspended on a fine fiber. After freezing started, a stream of small water droplets was ejected continuously from the surface of the freezing drop during the entire freezing period. This phenomenon terminated after completion of freezing.

Electric measurements were made in three ways: (i) by placing the probe of a sensitive electrometer into the stream of ejected small droplets; (ii) by placing the probe into the freezing water drop; and (iii) by observing the deflection of the stream of ejected small droplets in an electric field. The results indicated that the ejected small droplets carried net positive charge and that net negative charge was left on the residual frozen drop.

Experimental evidence has shown that positively charged droplets were generated by the freezing of a super-cooled water drop. The possible mechanisms for their generation are:

1) An increase of interior pressure. Unfrozen water in the form of small droplets was excreted from numerous pores which appeared to be weak spots found in cracks on the ice surface. Small spicules formed later at these same weak spots.

2) Condensation of water vapor, sublimated from the ice surface of the freezing drop. The temperature of the freezing drop was higher than that of the surrounding environment.

3) Formation of small droplets by the bursting of air bubbles, which were observed under the ice surface on the drop and in the interior of spicules. The air bubbles were formed as a result of the decrease of solubility of air in water when the temperature of the drop increased upon freezing. Observations of sequences of photomicrographs of the drop freezing and of the changes in temperature during the freezing period (Fig. 1) revealed that the vapor pressure gradient reversed direction twice during the freezing period. These reversals occurred when the freezing started and when the freezing was completed, and the water vapor molecules moved outward from the surface of the freezing drop during the entire freezing period A definite radial temperature gradient was maintained within the drop during the freezing period, with the colder region at the surface and the warmer region at the interior. A concentration of positive charge was found in the outer layer of the freezing drop (1) when the small droplets were ejected from the surface; these droplets carried net positive charge with them, while negative charge was left on the residual frozen drop.(ref: THERMOLELECTRIC EFFECT)

It is suggested that this newly observed phenomenon of the ejection of droplets is an important process which occurs under natural conditions in thunderclouds near the freezing level and where the water drops, carried from the base of the thundercloud by updrafts, are freezing. Moreover, it is possible that these ejected small droplets will also freeze after being carried upward to the higher and colder region of the thundercloud. It is widely accepted that the charge generation and separation processes in a thundercloud are closely associated with the development of precipitation and the main charge centers that appear above the freezing level. It is natural to associate their generation with the ice phase. Previously attention has been given to the fragmentation of a freezing water drop (1, 2) in the forms of shattering, splintering, or bursting, which has occurred occasionally during the freezing period. The observation presented here suggests that the ejection of small droplets by the freezing of a super-cooled water drop may be important in study of thundercloud dynamics and in the generation of thunderstorm electricity.

References and Notes

1. B. J. Mason and J. Maybank, Quart. J. Roy.Meteorol. Soc. 86, 176 (1960).

J. Latham and B. J. Mason, Proc. Roy. Soc. Ser. A Math. Phys. Sci . 260, 523 (1961).

2. D. A. Johnson, Proc. Int. Conf. Cloud Phys. (1968), p. 624.

J. Hallett, Quart. J. Roy. Meteorol. Soc. 94, 468 (1968).

J. E. Dye and P. V. Hobbs, J. Atmos. Sci. 25, 82 (1968).

19 May 1969; revised 10 August 1970

The Possible Mechanisms of
The Fragmentation and Charge Generation
during freezing of a super-cooled water drop in a thundercloud!
ROGER J CHENG-ASRC-UALBANY

Formation of micro-droplets by the bursting of air bubbles, which were observed at the INTERFACE of ICE and WATER on the surface of the FREEZING DROP(1mm). The air bubbles were formed as a result of the decrease of solubility of air in water when the temperature of the drop increased upon freezing. AIR has LESS SOLUBILITY in ICE than WATER
MICRO-DROPLETS (POSITIVELY CHARGED) ARE EJECTED THROUGH ICE SHELL of the FREEZING DROP by HIGH INTERIOR PRESSURE due to EXPANSION of AIR BUBBLES formed by PHASE CHANGE of WATER to ICE. AIR has LESS SOLUBILITY in ICE than WATER.
TIME-TEMPERATURE for the FREEZING of A SUPERCOOLED WATER DROP(1mm) in an environment of -20/C degree. The interior temperture of the unfrozen water drop is around 0/C degree, due to latent heat released during PHASE CHANGE of water to ice. .
SECTION OF HAILSTONE, OBSERVED by POLARIZED MICROSCOPE: REVIEWED MANY AIR BUBBLES ( BACK POCKETS) AGAINST COLORED ICE. THE BUBBLES WERE FORMED DURING FREEZING of WATER ON ICE SURFACE. THE RINGS OF BUBBLES ZONES INSIDE THE HAILSTONE INDICATED THIS HAIL HAD TRAVELLED ( UP & DOWN) MANY TIMES INSIDE THE THUNDERCLOUD.
MICRO-DROPLETS ( NO CHARGE) ARE ALSO FORMED by CONDENSATION of WATER VAPOR NEAR the SURFACE of the FREEZING DROP. THERE IS NO PHYSICAL SEPARATION

LIFE CYCLE of A WATER DROP in A THUNDERCLOUD

and THERMOELECTRIC EFFECT

LIFE CYCLE of A WATER DROP in THUNDERCLOUD
THREE STAGES of FRAGMENTATION

REFERENCE-

THERMOELECTRIC EFFECT:
Workman, E. J. and S. E. Reynolds
Electrical phenomena occurring during
the freezing of dilute aqueous solution
and their possible relationship to
thunderstorm electricity.

Phys. Rev., 78 254 259 ,I950.

THERMOELECTRIC EFFECT

Roger J. CHENG
Atmospheric Sciences Research Center, SUNY-ALBANY

COMMENTS on THUNDERBOLT PROJECT

A microscopic study on physical processes

of precipitation in a thundercloud

their nucleation, fragmentation and electrification,

by Roger J. CHENG -ASRC-UALBANY

1. LONDON TIMES, London, England, Jan. 4, 1971-Science Report-WEATHER,
“How Lightning May be Produced,”
.... .the observation of this separation process may therefore be the prime factor in the generation of thunderstorm electricity....”
2. ANN ARBOR NEWS, Jan. 31, 1971-The Science Beat, “Causes Lightning?”
. . .A. D. Moore, University of Michigan, Professor Emeritus of Electrical Engineering, and one of the world’s foremost authorities on electrostatics, says what could be the big ‘breakthrough’ in knowledge of what causes electrical discharges during thunder storms..... .the best explanation yet of the electrical discharges we hear as thunder and see as lightning...”
3. NEW SCIENTIST, London, England, Vol. 734, Jan. 1971. “
. . .Recent observation by Roger Cheng of the University of New York reveals a fascinating new microscopic process which almost certainly has an important bearing on how thunderclouds become charged to their high voltages....”
4. SUMMARY REPORT WEATHER MODIFICATION, Fiscal Year 1972,
by US Dept. of Commerce, National Oceanic & Atmospheric Administration
from chapter Cloud Electricity and Lightning Modification, “.....investigators from the State University of New York at Albany (Cheng, 1970) have been studying the freezing of super cooled water drops. suggestion that this mechanism might be important in the generation of thunderstorm electricity....”
5. Dr. J. V. Iribame, University of Toronto, Canada,
..... I believe that separation of liquid droplets, rather than ice splinters, may be a basic process causing electrification during riming of super cooled droplet....”
6. Dr. Herbert A. Phol, University of Cambridge, England,
.... .it opens up several new pathways. .1 am citing your work in my chapter in A.D. Moore’s forthcoming book on Electrostatics....”
7. Dr. Senichi Masuda, Chairman, Dept. of Electrical Engineering, University of Tokyo, Japan,
.... .1 would like to use the photomicrograph related to your article in SCIENCE, ..'Water Drop Freezing: Ejection of Microdroplets' in my book, “MODERN APPLIED ELECTROSTATICS”.
8. Dr. Leonard B. Loeb, Professor of Physics, University of California, Berkeley, “
... it could well be that this is one of the main sources of thunderstorm electrification—
especially since it has been shown that B.J. Mason’s splintering theory has proven inadequate.., you have made a most interesting discovery.
9. Dr. C. L. Andrews, Professor of Physics, SUNYA,
..... it is the most beautiful combination of mechanics, thermodynamics, electricity and magnetism and optics... you have initiated a field worthy of a few lifetimes of study...
10. Britanica Yearbook of Science and the Future, 1973, BRITANICA ENCYCLOPEDIA,
from Review of Atmospheric Science, by Dr. L. J. Battan, Professor of Atmospheric Science,
Director of the Institute of Atmospheric Physics, University of Arizona,
.... .this separation mechanism could possibly generate lightning in storm clouds...
11. The World Book Science Annual 1974, SCIENCE YEAR from Science Report “The New Rainmaker”
by Dr. C. L. Hosler, Dean, College of Earth & Mineral Sciences, Penn State University, “
...tiny particles of ice break off..., and scattering electrically charged micro-droplets..., such studies help explain rapid changes in the cloud...”
12. Dr. Choji Magono, Professor, Geophysical Sciences, Hokkaido University, Japan,
Chairman: Section of Ice and Snow Crystals, International Conference on Cloud Physics, 1968 in his keynote paper at the conference, .... .Cheng (1967) observed many clumped ice crystals and considered that the clumping was caused by Coulomb force. The author also observed clumped ice crystals...and found that the clumping seemed to occur under a microscope by Coulomb force...”
13. From “Aggregation Phenomena of Ice Crystals,” Journal of the Meteorological Society of Japan,
Vol. 50, No. 5, October, 1972, “......it is noted.. .that the ice crystals observed were in a state of growth in which the charge separation could occur within an ice crystal, as pointed out by Cheng (1967).”

INTERNATIONAL CITATIONS

PHOTOMICROSCOPICAL INVESTIGATION of the FRAGMENTATION of
HYDROMETEORS in the LABORATORY

ROGER J CHENG-ASRC-SUNYA

The MICROSCOPE
JULY 1973, VOL.21, NO.3

The MICRO-WORLD in the ATMOSPHERE

ATMOSPHERIC PHYSICS & CHEMISTRY -

REFERENCES

Roger J. CHENG -ASRC-UALABNY

.1. SCIENCE (1970)

"Water Drop Freezing: Ejection of Microdroplets"****

2. UMSCHAU in WISSENSCHAFT and TECHNIK (1971) "Das Gefruern von Wassentropfen: Ausstobung von Kleintrofchen"

.

3. INTERNATIONAL CONFERENCE on CLOUD PHYSICS (1972)

"Three Stages of Massive Fragmentation of Hydrometeors and Electrification in the Atmosphere"

4. A. INTERNATIONAL CONFERENCE on NUCLEATION (1973).

.B. THE JOURNAL OF WEATHER MODIFICATION (1974).****

"The Mechanism of Multiplication Process of Glaciation in the Atmosphere"

5. AMS CLOUD PHYSICS & ATMOSPHERIC ELECTRICITY CONFERENCE (1978)

"Ice Pellet Melting: Ejection of Micro-droplets".

6. JOURNAL de RECHERES ATMOSPHERIQUES (1971)

"The Production of Ice Crystal Fragments by Sublimation and Electrification" (Schaefer & Cheng)****

.

7. QUARTERLY JOURNAL of the ROYAL METEOROLOGICAL SOCIETY (1991)

"Charge Separation Associated with Frost Growth" (Williams, et. al)

.

8. INTERNATIONAL CONFERENCE on CLOUD and PRECIPITATION (1992)

"Sublimational Break-up of Secondary Ice Particles Associated with Frost Growth"

.

9. INTERNATIONAL CONFERENCE on ATMOSPHERIC ELECTRICITY (1992)

"Fragmentation of Charged Ice Particles Associated with Frost Growth"

.

10. INTERNATIONAL CONFERENCE on CLOUD PHYSICS (1968)

A. "Problem on Physical Understanding of Snowfall Phenomena"(Magono)

B. "The Effect of the Nucleus on Ice Crystal Structure" (Schaefer and Cheng)

.

11. ASRC YELLOWSTONE FIELD RESEARCH EXPEDITION

A. "Joined Ice Crystals from Seeding Experiments" (1967)

B. "Microscopic Study of Ice Crystals in Yellowstone" (Magono, et al) (1968)

.

12. JOURNAL of the METEOROLOGICAL SOCIETY of JAPAN (1972)

"Aggregation Phenomena of Ice Crystals" (Magono, et al).

.

13. THE MICROSCOPE (1970)

"Microscopic Study of Lead Iodide - Nucleated Ice Crystals" ****

(Cheng & Hogan).

.

14. UMSCHAU in WISSENSCHAFT und TECHNIK (1971)

"Blei in Eiskritallen"

.

15. BULLETIN of AMERICAN METEOROLOGICAL SOCIETY (1973)

"Crystallization of Silver Iodide"****

.

16. WEATHERWISE (1985)

"Weather in the Small Scale" ****

****: FEATURED COVER ARTICLES by EDITORS