US3127107A - Generation of ice-nucleating crystal - Google Patents

Generation of ice-nucleating crystal Download PDF

Info

Publication number
US3127107A
US3127107A US3127107DA US3127107A US 3127107 A US3127107 A US 3127107A US 3127107D A US3127107D A US 3127107DA US 3127107 A US3127107 A US 3127107A
Authority
US
United States
Prior art keywords
ice
core
fuse
clouds
crystals
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
Publication date
Application granted granted Critical
Publication of US3127107A publication Critical patent/US3127107A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01GHORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G15/00Devices or methods for influencing weather conditions
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S149/00Explosive and thermic compositions or charges
    • Y10S149/117Smoke or weather composition contains resin

Definitions

  • Ice-nucleating crystals in particular silver iodide crystals, have heretofore been generated for introduction into clouds by means of special generators located on the ground or attached to aircraft.
  • the ice-nucleating materials are placed in a zone maintained at a temperature at which they have an appreciable vapour pressure, which in the case of silver iodide is at least 1500 C., and are thus vapourized into the atmosphere where they recrystallize upon contact with the coolor
  • the crystals are carried aloft by ascending air currents whereas aircraft generators produce the crystals within or in the near vicinity of the clouds.
  • Typical generators are devices where a solution of silver iodide in acetone is injected or sprayed into a propane, oxyapropane or hydrogen flame or where coke impregnated with silver iodide is burned in an air-blown crucible furnace or where a rope or wick impregnated with silver iodide is burned in an open flame or in an air-propane blast turnace.
  • Another object or" this invention is to provide a new device for the aforesaid generation of crystals, the said device being simpler, more versatile and cheaper than the generators of the prior art and having'a much greateroutput rate than such generators.
  • the new process of this invention comprises detonating contiguously to the clouds a detonating fuse whose core of high explosive contains from about 3.5% to about 20% by weight of an ice-nucleating material.
  • a detonating fuse is an elongated cord-like material consisting of a core of high explosive contained within a waterproof covering and reinforced with various countering materials and has a velocity of detonation of the order or" 20,000 feet per second.
  • a typical fuse comprises a core of pentaerythritol tetran-itrate, a textile sheath surrounding said core to contain the same, an asphalt layer surrounding said sheath to waterproof it and prevent said core from sifting, a braided textile layer protecting said asphalt layer, a tape covering for said textile layer to provide for the water proofing and flexibility, a second textile sheath surrounding said tape covering to protect it, and a waterproofing layer of 'Wax or plastic surrounding said second textile sheath.
  • the new ice-nucleating crystal generator of this invention thus consists of a detonatin-g fuse having a core of high explosive containing from about 3.5% to about 3 20% by weight of an ice-nucleating material.
  • the 20% upper limit .on the concentration of ice-nucleating material in the explosive core of the fuse is set by the fact that the efiiciency of the fuse decreases as the said concentration increases.
  • the new fuse of this invention is of: simpler and cheaper construction and requires no upkeep and it is also more versatile in that it can be easily transported and detonated on the ground or can be carried aloft by small balloons, aircraft or rockets cfor detonation in the air.
  • Another advantage of the fuse is that its ice-nucleating material content being known, the amount of ice-nucleating material to be released in the atmosphere is simply determined and controlled by the length of fuse detonated.
  • the fuse can be detonated by ordinary means, viz by safety fuse and blasting cap or by electric blasting cap. It can also be initiated by a time tuse when carried by a balloon provided that the rate of ascent of the balloon is known.
  • a desensitizer such as glycerol must be incorporated with the explosive for safety purposes.
  • Total AgI part1cles N 100 where N is the number of crystals produced in the cold chamber by the syringe sample.
  • a device for generating crystals of ice-nucleating materials for introduction of the same into supercooled atmospheric clouds which comprises a detonating fuse which is an elongated, cord-like material having a core of desensitized pentaerythri-tol tetranitrate and a protective sheath about said core, said core also containing from about 3.5% to about 20% by weight of silver iodide.
  • a process for generating crystals of ice-nucleating materials for introduction of the same into supercooled atmospheric clouds which comprises detonating contiguously to the clouds a detonating fuse which is an elongated, cord-like material having a core of desensitized pentaerytbritol tetranitrate and a protective sheath about said core, said core also containing from about 3.5% to about 20% by weight of silver iodide.

Description

United States Patent "cc 3,127,107 GENERATION 0F ICE-NUCLEATENG CRYSTALS John Patrick Merryweather, New Castle, Pa., assign'or to Canadian Safety Fuse Company Limited, Montreal, Quebec, Canada, a corporation of Canada No Drawing. Filed May 29, 1961, Ser. No. 113,063 4 Claims. (Cl. 239-2) This invention pertains to the art of cloud seeding. It relates to a new process and a new device for generating crystals of ice-nucleating materials for introduction of the same into supercooled atmospheric clouds.
The seeding of clouds, i.e. the introduction into supercooled atmospheric clouds of materials which cause the formation of ice crystals in the clouds, has been practised for a number of years for the purpose of controlling or modifying weather conditions. One method of cloud seeding is described in United States Patent No. 2,570,867 issued on October 9, 1951, to V. J. Schaefer, and consists of introducing into the clouds particles of solid carbon dioxide, the latter producing within the clouds zones of low temperature at which ice crystals form spontaneously. A preferred method, however, is that disclosed in United States Patent No. 2,527,231 issued on October 24', 1950, to V. J. Schaefer and B. Vonnegut, and consists of introducing into the clouds crystals of materials foreign with respect to the clouds and having a space group and unit cell dimensions closely approximating those of ice crystals, the said foreign crystals acting as nuclei for the formation of ice crystals the clouds. Such foreign crystalline materials are known in the art as ice-nucleate ing materials and include chemical substances such as silver iodide, lead iodide, cupric sulphide, etc., as Well as natural minerals such as zincite, nephelite and apatite, A list of ice-nucleating materials is given at page 227 of Physics of Precipitation, Publication No. 746 (1960) of the American Geophysical Union of the National Academy of Sciences-National Research Council. It is with the latter preferred method that the present invention is concerned. 7
Ice-nucleating crystals, in particular silver iodide crystals, have heretofore been generated for introduction into clouds by means of special generators located on the ground or attached to aircraft. In these generators, the ice-nucleating materials are placed in a zone maintained at a temperature at which they have an appreciable vapour pressure, which in the case of silver iodide is at least 1500 C., and are thus vapourized into the atmosphere where they recrystallize upon contact with the coolor In the case of generators located on the ground, the crystals are carried aloft by ascending air currents whereas aircraft generators produce the crystals within or in the near vicinity of the clouds. Typical generators are devices where a solution of silver iodide in acetone is injected or sprayed into a propane, oxyapropane or hydrogen flame or where coke impregnated with silver iodide is burned in an air-blown crucible furnace or where a rope or wick impregnated with silver iodide is burned in an open flame or in an air-propane blast turnace.
3,127,17 Patented Mar. 31, 1964 Although the efficiency of such generators, i.e. the number of crystals thereby produced per gram of silver iodide consumed, is satisfactory in that it varies from 10 to 10 their output rate, i.e. the number of crystals produced per second, varies trom 10 to 3x10 and is thus relatively low. This is particularly undesirable in the case of ground generators since the crystal must ascend to considerable heights before reaching clouds and are thus subject to greater diffusion during their ascent. In addition, the use of such generators is expensive due to their cost of manufacture, transportation and upkeep. It is an object of this invention to provide a process for generating crystals of ice-nucleating materials tor introduction of the same into supercooled atmospheric clouds, which process constitutes a complete departure from the prior art.
Another object or" this invention is to provide a new device for the aforesaid generation of crystals, the said device being simpler, more versatile and cheaper than the generators of the prior art and having'a much greateroutput rate than such generators.
Additional objects of the invention will appear hereinafter.
. Broadly speaking, the new process of this invention comprises detonating contiguously to the clouds a detonating fuse whose core of high explosive contains from about 3.5% to about 20% by weight of an ice-nucleating material.
As is Well known, a detonating fuse is an elongated cord-like material consisting of a core of high explosive contained within a waterproof covering and reinforced with various countering materials and has a velocity of detonation of the order or" 20,000 feet per second. A typical fuse comprises a core of pentaerythritol tetran-itrate, a textile sheath surrounding said core to contain the same, an asphalt layer surrounding said sheath to waterproof it and prevent said core from sifting, a braided textile layer protecting said asphalt layer, a tape covering for said textile layer to provide for the water proofing and flexibility, a second textile sheath surrounding said tape covering to protect it, and a waterproofing layer of 'Wax or plastic surrounding said second textile sheath.
It has been found that by incorporating the aforesaid amount of ice-nucleating material into the high explosive core of detonating fuse, an enormous instantaneous rate of ice-nucleating crystal generation is obtained upon detonation of the fuse which cannot be matched by any other known process and/or device. Thus it has been found that a detonating fuse whose core contains 10 grains per foot of silver iodide and 50 grains per foot of pentaerythritol tetranitrate releases on detonation 10 crystals of silver iodide per 18" length while detonating at the rate of 20,000 feet per second. The efliciency of such a fuse is lower than that of prior art generators in that it ranges from 32x10 to 1.7)(10 but is very largely offset by its high output rate.
The new ice-nucleating crystal generator of this invention thus consists of a detonatin-g fuse having a core of high explosive containing from about 3.5% to about 3 20% by weight of an ice-nucleating material. The 20% upper limit .on the concentration of ice-nucleating material in the explosive core of the fuse is set by the fact that the efiiciency of the fuse decreases as the said concentration increases.
In addition to being superior to prior art crystal generators from the standpoint of output rate as mentioned above, the new fuse of this invention is of: simpler and cheaper construction and requires no upkeep and it is also more versatile in that it can be easily transported and detonated on the ground or can be carried aloft by small balloons, aircraft or rockets cfor detonation in the air. Another advantage of the fuse is that its ice-nucleating material content being known, the amount of ice-nucleating material to be released in the atmosphere is simply determined and controlled by the length of fuse detonated.
The fuse can be detonated by ordinary means, viz by safety fuse and blasting cap or by electric blasting cap. It can also be initiated by a time tuse when carried by a balloon provided that the rate of ascent of the balloon is known.
When the nature of the ice-nuoleating material is such as to sensitize the high explosive which constitutes the core of the fuse, as is the case of silver iodide with pentaerythritol tetranitrate, a desensitizer such as glycerol must be incorporated with the explosive for safety purposes.
The invention will be more fully illustrated by the following example which is not intended to limit its scope in any way.
EXAMPLE Samples of detonating fuse containing various proportions of silver iodide (Agl) in their glycerol-desensitized pentaerythritol tetranitrate (PETN) core were detonated in a test hut having a capacity of 300 cubic feet (85x10 00.). The resulting smoke cloud was then sampled with a 100 cc. glass syringe and the syringe sample was injected into a cold chamber having a capacity of 2000 cc. maintained at temperatures of from 8.5 C. to -19 C. The number of ice crystals produced in the chamber by the silver iodide particles was estimated visually with a 300 watt projector light source and the total number of silver iodide particles produced in the hut established by the following formula:
Total AgI part1cles=N 100 where N is the number of crystals produced in the cold chamber by the syringe sample.
The results are given in the following table.
4 TABLE Fuse core in Total AgI partigrains/foot Cold chamber cles produced per temperature gram of Ag]: in AgI PETN C.) fuse core 5.0 12 1. 3X10 5.0 45 -13 1. 3X10 5.0 45 ---13 2. 0X10 5. 0 45 13 3. 6X10 5.0 45 -13 2X10 10. 0 8. 5 3. 2X10 10. 0 50 8. 5 8. 5x10 10.0 50 12 8.5 10 10. 0 50 12 1.7)(19 10.0 50 12 5.1X10 10. 0 50 12 1. 3X10 10. 0 50 15 8. 5X10 10. 0 50 15 1.7X10 10. 0 50 17 1.7)(10 It is seen from the above table that the amount of silver iodide particles produced per gram of silver iodide in the fuse core decreases with the increasing ratio of silver iodide to pentaerythritol tetranitrate in the core.
What I claim is:
l. A device for generating crystals of ice-nucleating materials for introduction of the same into supercooled atmospheric clouds which comprises a detonating fuse which is an elongated, cord-like material having a core of desensitized pentaerythri-tol tetranitrate and a protective sheath about said core, said core also containing from about 3.5% to about 20% by weight of silver iodide.
2. A device as claimed in claim 1 wherein the silver iodide is present in the core in a concentnation of from about 4.0% to about 17% by weight.
3. A process for generating crystals of ice-nucleating materials for introduction of the same into supercooled atmospheric clouds which comprises detonating contiguously to the clouds a detonating fuse which is an elongated, cord-like material having a core of desensitized pentaerytbritol tetranitrate and a protective sheath about said core, said core also containing from about 3.5% to about 20% by weight of silver iodide.
4. A process as claimed in claim 3 wherein the silver iodide in the fuse core is present in a concentration of from about 4.0% to about 17% by weight.

Claims (1)

  1. 3. A PROCESS FOR GENERATING CRYSTALS OF CIE-NUCLEATING MATERIALS FOR INTRODUCTION OF THE SAME INTO SUPERCOOLED ATMOSPHERIC CLOUDS WHICH COMPRISES DETONATING CONTIGUOUSLY TO THE CLOUDS A DETONATING FUSE WHICH IS AN ELONGATED, CORD-LIKE MATERIAL HAVING A CORE OF DESENSITIZED PENTAERYTHRITOL TETRANITRATE AND A PROTECTIVE SHEATH ABOUT SAID CORE, SAID CORE ALSO CONTAINING FROM ABOUT 3.5% TO ABOUT 20% BY WEIGHT OF SILVER IODIDE.
US3127107D Generation of ice-nucleating crystal Expired - Lifetime US3127107A (en)

Publications (1)

Publication Number Publication Date
US3127107A true US3127107A (en) 1964-03-31

Family

ID=3456132

Family Applications (1)

Application Number Title Priority Date Filing Date
US3127107D Expired - Lifetime US3127107A (en) Generation of ice-nucleating crystal

Country Status (1)

Country Link
US (1) US3127107A (en)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3272434A (en) * 1963-06-03 1966-09-13 Albert C Zettlemoyer Nucleating process
US3375148A (en) * 1967-01-17 1968-03-26 Navy Usa Pyrotechnics comprising silver iodate, ammonium nitrate, nitrocellulose and nitrate esters
US3441214A (en) * 1967-01-09 1969-04-29 Weather Eng Corp Of Canada Ltd Method and apparatus for seeding clouds
US3567117A (en) * 1969-08-29 1971-03-02 Hedco Ice nuclei formation
US3703991A (en) * 1971-07-23 1972-11-28 Hedco Snow precipitator
US3877642A (en) * 1974-08-09 1975-04-15 Us Navy Freezing nucleant
US3915379A (en) * 1968-10-10 1975-10-28 Us Navy Method of controlling weather
US4191125A (en) * 1978-07-03 1980-03-04 Akzona Incorporated Freeze indicator
US5174498A (en) * 1990-01-15 1992-12-29 Yeda Research And Development Co. Ltd. Cloud seeding
WO1994008096A1 (en) * 1992-10-02 1994-04-14 Kjoelseth Paul A system for dissipation or dispelling of fog
US5357865A (en) * 1991-02-22 1994-10-25 Water Research Commission Method of cloud seeding
US5441200A (en) * 1993-08-20 1995-08-15 Rovella, Ii; Ernest J. Tropical cyclone disruption
US7290722B1 (en) 2003-12-16 2007-11-06 Snow Machines, Inc. Method and apparatus for making snow

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2257360A (en) * 1940-02-08 1941-09-30 Trojan Powder Co Desensitized pentaerythritol tetranitrate explosive
FR1010878A (en) * 1950-02-06 1952-06-16 Improved rocket or hail bomb

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2257360A (en) * 1940-02-08 1941-09-30 Trojan Powder Co Desensitized pentaerythritol tetranitrate explosive
FR1010878A (en) * 1950-02-06 1952-06-16 Improved rocket or hail bomb

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3272434A (en) * 1963-06-03 1966-09-13 Albert C Zettlemoyer Nucleating process
US3441214A (en) * 1967-01-09 1969-04-29 Weather Eng Corp Of Canada Ltd Method and apparatus for seeding clouds
US3375148A (en) * 1967-01-17 1968-03-26 Navy Usa Pyrotechnics comprising silver iodate, ammonium nitrate, nitrocellulose and nitrate esters
US3915379A (en) * 1968-10-10 1975-10-28 Us Navy Method of controlling weather
US3567117A (en) * 1969-08-29 1971-03-02 Hedco Ice nuclei formation
US3703991A (en) * 1971-07-23 1972-11-28 Hedco Snow precipitator
US3877642A (en) * 1974-08-09 1975-04-15 Us Navy Freezing nucleant
US4191125A (en) * 1978-07-03 1980-03-04 Akzona Incorporated Freeze indicator
US5174498A (en) * 1990-01-15 1992-12-29 Yeda Research And Development Co. Ltd. Cloud seeding
US5357865A (en) * 1991-02-22 1994-10-25 Water Research Commission Method of cloud seeding
WO1994008096A1 (en) * 1992-10-02 1994-04-14 Kjoelseth Paul A system for dissipation or dispelling of fog
US5441200A (en) * 1993-08-20 1995-08-15 Rovella, Ii; Ernest J. Tropical cyclone disruption
US7290722B1 (en) 2003-12-16 2007-11-06 Snow Machines, Inc. Method and apparatus for making snow

Similar Documents

Publication Publication Date Title
US3127107A (en) Generation of ice-nucleating crystal
Cadle et al. The global scale dispersion of the eruption clouds from major volcanic eruptions
Pinto et al. Self‐limiting physical and chemical effects in volcanic eruption clouds
US2522074A (en) Method of rendering infrared radiation visible employing doubly activated alkaline earth sulfide phosphors
Donn et al. On the early history of the earth
Wexler Spread of the Krakatoa volcanic dust cloud as related to the high-level circulation
Andres et al. SO 2 from episode 48A eruption, Hawaii: Sulfur dioxide emissions from the episode 48A East Rift Zone eruption of Kilauea volcano, Hawaii
US3630950A (en) Combustible compositions for generating aerosols particularly suitable for cloud modification and weather control and aerosolization process
Lockyer The meteoritic hypothesis: a statement of the results of a spectroscopic inquiry into the origin of cosmical systems
US3755182A (en) Nitrogen generating compositions
Hayhurst et al. Mechanism for producing NO from nitrogen in flames
US3252455A (en) Hydrogen fuel cell and generator
Schunk et al. Auroral N2 vibrational excitation and the electron density trough
USRE29142E (en) Combustible compositions for generating aerosols, particularly suitable for cloud modification and weather control and aerosolization process
Swider Sodium chemistry: A brief review and two new mechanisms for sudden sodium layers
Starzhinskiy et al. New Trends in the Development of A $^{\rm II} $ B $^{\rm VI} $-Based Scintillators
US1103490A (en) Rain-maker.
Miller Elements of Chemistry: Inorganic chemistry 1871. xxii.[2], 825p
US4316816A (en) Method for preparing copper-aluminum-gold-activated zinc-sulfide phosphors
Gezci et al. Edge emission in zinc selenide
Bancroft Hail and dust
US2493763A (en) Method of producing lightweight aggregate from clay
Gladysheva Atmospheric anomalies in summer 1908: Water in the atmosphere
US2912929A (en) Drill mine
RU2181239C2 (en) Pyrotechnic compound for changing weather conditions