WO2021152336A1

WO2021152336A1 - Method of cloud seeding using natural ice nucleating agents

Info

Publication number: WO2021152336A1
Application number: PCT/GR2021/000009
Authority: WO
Inventors: Ilias ANASTASOPOULOS
Original assignee: University Of Thessaly
Priority date: 2020-01-29
Filing date: 2021-01-28
Publication date: 2021-08-05
Also published as: GR20200100042A

Abstract

The present invention relates to a method of seeding clouds for the control of atmospheric precipitation (rainfall, snowfall, hailfall and fog) that uses as seeding agents, ice nucleating agents of natural origin either plant or mineral.

Description

DESCRIPTION

METHOD OF CLOUD SEEDING USING NATURAL ICE NUCLEATING

AGENTS

The technical field of the present invention pertains to a method for cloud seeding using natural ice nucleating agents.

In nature water can exist in, solid (ice), liquid, or vapor, phase. The first appearance of a thermodynamically stable ice phase is called ice nucleation (Vali et al 2015). Freezing is a phase transition process in which a liquid turns into solid. The freezing process starts with ice nucleation, when an ice embryo (ice nucleus) is formed followed by crystallization that is the subsequent growth of the nucleus by attracting water molecules and ordering them in an ice lattice structure.

During crystallization an amount of energy is released, the latent heat of fusion, that can be measured no invasively using a thermal camera as described in the publication of Zaragotas et al (2016).

Homogeneous ice nucleation is called the ice nucleation process that starts and proceeds without any foreign substance aiding the process, whereas heterogeneous ice nucleation is aided by the presence of a foreign substance, usually referred to as ice nucleating agent (Vali et al 2015).

There are two distinct heterogeneous ice nucleation modes. The deposition nucleation which refers to supersaturated vapors on an ice nucleating agent and freezing nucleation which refers to the ice nucleation of supercooled liquid (water that remains liquid at subzero temperature) due to the presence of an ice nucleating agent.

The freezing nucleation modes are further divided in immersion freezing initiated by an ice nucleating agent in supercooled water, contact freezing initiated by an ice nucleating agent which comes into contact with a supercooled liquid and condensation freezing, initiated by the formation of liquid on a cloud condensation nucleus. Cloud condensation nuclei are tiny aerosol particles on whose surfaces water vapor condenses.

Warm natural ice nucleating agents are active at high subzero temperatures, between -1 °C to -8 °C. An ice nucleating agent may be a natural microorganism like an ice nucleation active bacterium, or a virus, or a fungus, or a lichen, (e.g. US 5,169,783) or an organism such as for example a plant that has at least one ice nucleation gene, that renders it capable of producing an ice nucleation protein. Snomax (SNOMAX International, Englewood, CO) is an ice nucleating agent that is commercially available and has been used in cloud seeding experiments (Ward and Demott 1989, Woodley and Henderson 1990). The production of SNOMAX starts with fermentation of Pseudomonas syringae bacterial culture, then the ice nucleation proteins are separated from the rest of the culture using special filters and lastly they are subjected to freeze-drying. Despite the well-defined process for producing SNOMAX, Polen et. al (2016) reported on the unstable nature of Snomax’s ice nucleation properties. Apart from the ice nucleation proteins other organic compounds that can act as ice nucleators include certain phospholipids, amino acids (Parungo et al 1967), carbohydrates and alcohols (UN 5,174,498).

The ice nucleating agents can vary in size e.g. microparticles, nanoparticles, powders, mineral particles and chemical compositions e.g. silver iodide, silver oxide, or aluminium oxide, because of the way they have been processed or their composition. IceStar (Asymptote, Cambridge, UK) is a mineral nucleator produced by Asymptote, which holds several related patents referring to framework silicate minerals and feldspar in particular,

WO/2014/091216, U.S. Patent No. 10015958 and U.S. Patent No. 0327538, or a formulation containing framework silicate minerals and ammonium salt for promoting spontaneous ice nucleation WO/2017/194954. The cloud seeding methods are generally used for the control of atmospheric precipitations, where in some cases we pursue their increase, as for example in cases of rainfalls or snowfalls, whereas in others we pursue their repression or their decrease like in hailfalls and in fog that limits visibility f.x in highways and airports.

The cloud seeding methods are either hygroscopic or glaciogenic. Hygroscopic cloud seeding methods involve the dispersion of aerosolized salt by aircraft into the base of convective updrafts. The method has been used in convective clouds with warm cloud bases in order to cause rainfall and increase in visibility in fog conditions near airports (Haupt et al 2018).

Glaciogenic seeding can also be applied by aircraft, but also by ground generators and involves dispersing aerosolized silver iodide, or dry ice into a cloud containing supercooled droplets (Deshler et al 1990). It has been used in severe thunderstorms for hail protection (by reducing hail size), over target river basins in attempts to increase snowfall, as well as in cumulo-nimbus and cumulus congestus to cause rainfall and in supercooled fog to increase visibility close to airports.

French et al 2018 proved that glaciogenic seeding in orographic clouds can lead to precipitation (snowfall) that would otherwise not fall within the targeted region.

Silver iodide is the most common ice nucleator used in cloud seeding. Under certain condition, it may affect living organisms in terrestrial or aquatic ecosystems (Fajardo et al 2016). Cloud seeding agents that can nucleate ice as efficiently as silver iodide have been identified long time ago, as for example some crystalline organic substances (Parungo et al.1967) and certain bacteria (Levin et al. 1987).

Cloud seeding with silver iodide remains the most popular method of ice seeding despite the concerns raised the last decades about its use and also despite the fact that its consequences to human health and the environment remain controversial (Haupt et al 2018).

The immersion freezing relates to the cloud formation (Murray, et al 2012). With the present invention I propose the replacement of silver iodide and other common cloud seeding agents with natural cloud seeding agents, of plant or mineral origin that have ice nucleation ability, as was proven with a series of immersion freezing experiments. Some of the seeding agents we identified exhibited exceptionally high ice nucleation activity in comparison to the most efficient ice nucleators known. The proposed method of natural ice nucleators is suitable for existing seeding technologies that use airplanes or guns on the ground and does not require the use of specific constructs as e.g. in cloud ionization, electric rainmaking, or laser-guided weather modification projects. It is more economical than silver iodide which for many years till today constitutes the common cloud seeding technology.

The proposed method in a preferred embodiment uses biological seeding agents of plant origin (as e.g. with Hippophaes plant) which are not toxic for man and the living environment.

In another preferred embodiment the proposed method mimics natural precipitation phenomena (as e.g. with mineral dust present in the atmosphere).

In continuation experiments are presented that are not restrictive to the invention. All experimental results presented below were obtained by using a technological platform and the appropriate methodology described in Zaragotas et al 2016.

Experiment 1. Hail Supression

Table 1A. Nucleation temperatures of 96 hail samples (above). n.p. : SD T50

Table 1. Average nucleation temperature (np), standard deviation (SD) and temperatures at which 50% of samples froze (T50).

As shown in Table 1 A, the warmest nucleation temperature measured for the pea size hailstones collected on 18/4/2019 from Terpsithea Larissa, Greece was -3,29 °C (out of 96 measurements), whereas the average nucleation temperature was -4,30 °C (Table 1B). Thus, an effective hail suppression program must involve the use of an ice nucleant warmer than -3,29 °C.

Experiment 2. Comparative experiment (sea salts and potassium feldspar)

SO T50

Table 2. Nucleation temperatures of 96 potassium feldspar samples (K Feld), bottled water (H20 Bottled THEONI) (negative control) and sea salts at five different concentrations. Average nucleation temperature (np), standard deviation (SD) and temperature at which 50% of samples froze (T50).

The sea salts are inherently hygroscopic since they take up moisture from the air (Zieger et al 2017). Lahav& Rosenfeld (2003) reported seeding concentrated brine from the Dead Sea in an effort to produce more cloud condensation nuclei (CCN) of desirable size, in appropriate concentrations for long time periods, and less costly than the usual hygroscopic flare seeding systems.

In experiment 2 we used an artificial sea salt mixture (Sigma Aldrich, S9883) representative of the inorganic mass fraction of most oceanic seawater that has already been used in nebulizer chamber experiments (Zieger et al 2017).

Moreover we compared the ice nucleation activity of sea salts with that of potassium feldspar (K-Feldsar). It is known that not all feldspars are equally effective in their ice nucleating ability (Harrison etal.2016). We have identified a sample that nucleates ice remarkably higher than any other known and selected it to be used in our measurements as a reference (Table 2).

The feldspar sample included in the above experiment showed clearly ice nucleating activity at warmer temperatures than the sea salt mixture at the same concentrations.

Experiment 3 Comparative experiment (Aerosols of mineral and biological origin)

It is known that various aerosols of mineral or biological origin can act as cloud condensation nuclei (Kumar et al 2011 ; Hiranuma et al 2019). The samples of mineral origin used were quarz (Quarz), and illite (Nx lllite) (illite NX has been referred to in many relevant atmospheric studies, like f.x. Hiranuma et al 2019, Welti et al. 2009), whereas the samples of biological origin used were fibrous cellulose (Fibrous cellulose, FC), and microcrystalline cellulose (Microcrystalline cellulose, MCC).

I K /ihh i SO T50

Table 3. Nucleation temperatures of bottled water (negative control), tourmaline (Tour) in two concentrations 0,46 and 0,7 g/10ml_, Quarz, illite (NX illite, fibrous cellulose (FC), and microcrystalline cellulose (MCC) in concentrations 0,5g/10mL. Average nucleation temperature (np), standard deviation (SD) and temperature at which 50% of samples froze (T50).

As proven from the results referred in table 3 the ice nucleation activity of tourmaline, which belongs to the silicate minerals, was superior of the corresponding of the rest of the samples. Experiment 4. Comparative experiment (silver iodide and potassium feldspar)

In figures 1 and 2 results obtained from two different freezing experiments performed under identical freezing conditions are presented and concerned the freezing profiles of 8 samples of silver iodide suspension in water (figure 1) and of 6 samples of potassium feldspar suspended in water (figure 2). Both silver iodide and potassium feldspar do not adequately dissolve in water. The ice nucleation activity of both samples declined with decreasing concentration and the observed decline was higher with potassium feldspar than with silver iodide. The same freezing profiles were obtained also at 1 to 10 dilutions, though the diluted potassium feldspar was freezing significantly less than the silver iodide. Therefore, it is expected in seeding applications, potassium feldspar to be used in about ten times the quantity of silver iodide.

Experiment 5 Comparative experiment (Hippophaes and Snomax)

In the early 90’s, pilot experiments of seeding clouds with Snomax proved to be successful (Ward and DeMott 1989). In this experiment we used Snomax as a positive control and we compared its ice nucleation activity with that of lyophilized Hippophaes leaf extract. The ice nucleation activity of Hippophaes, though inferior to Snomax, was comparable to it.

SD 150

Table 4. Nucleation temperatures of 96 Hippophae rhamnoides lyophilized leaf extracts 0,1g/mL and Snomax. Average nucleation temperature (np), standard deviation (SD) and temperature at which 50% of samples froze (T50). Bibliographic references

Deshler, T., Reynolds, D. W., & Huggins, A. W. (1990). Physical response of winter orographic clouds over the Sierra Nevada to airborne seeding using dry ice or silver iodide. Journal of Applied Meteorology, 29(4), 288-330. French, J. R., Friedrich, K., Tessendorf, S. A., Rauber, R. M., Geerts, B., Rasmussen, R. M., ... & Blestrud, D. R. (2018). Precipitation formation from orographic cloud seeding. Proceedings of the National Academy of Sciences, 115(6), 1168-1173. Harrison, A. D., Whale, T. F., Carpenter, M. A., Holden, M. A., Neve, L, O'Sullivan, D., ... & Murray, B. J. (2016). Not all feldspars are equal: a survey of ice nucleating properties across the feldspar group of minerals. Atmospheric Chemistry and Physics, 16(17), 10927-10940. Haupt, S. E., Kosovic, B., McIntosh, S. W., Chen, F., Miller, K., Shepherd, M., ... & Drobot, S. (2018). 100 years of Progress in Applied Meteorology Part III: Additional Applications. Meteorological Monographs.

Hiranuma, N., Adachi, K., Bell, D. M., Belosi, F., Beydoun, H., Bhaduri, B., ... & Cory, K. M. (2019). A comprehensive characterization of ice nucleation by three different types of cellulose particles immersed in water. Atmospheric Chemistry and Physics, 19(7), 4823-4849.

Kumar, P., Sokolik, I. N., & Nenes, A. (2011). Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals. Atmospheric Chemistry and Physics, 11(7), 3527.

Levin, Z., Yankofsky, S. A., Pardes, D., & Magal, N. (1987). Possible application of bacterial condensation freezing to artificial rainfall enhancement. Journal of climate and applied meteorology, 26(9), 1188-1197.

Lahav, R., & Rosenfeld, D. (2003). Natural and artificial rain enhancement by sea spray. American meteorological society 83rd annual meeting, Long Beach (p. J.5.6).

Murray, B.J.; O’Sullivan, D.; Atkinson, J.D.; Webb, M.E. (2012) Ice nucleation by particles immersed in supercooled cloud droplets. Chem. Soc. Rev. 41, 6519-6554

Parungo, F., and J. Lodge Jr., (1967) Amino acids as ice nucleators. J. Atmos. Sci., 24, 274-277.

Polen, M., Lawlis, E., & Sullivan, R. C. (2016). The unstable ice nucleation properties of Snomax® bacterial particles. Journal of Geophysical Research: Atmospheres, 121(19), 11-666.

Vali, G., DeMott, P. J., Mohler, O., & Whale, T. F. (2015). A proposal for ice nucleation terminology. Atmospheric Chemistry and Physics, 15(18), 10263-10270. Zaragotas, D., Liolios, N. T., & Anastassopoulos, E. (2016). Supercooling, ice nucleation and crystal growth: a systematic study in plant samples. Cryobiology, 72(3), 239-243.

Zieger, P., Vaisanen, O., Corbin, J. C., Partridge, D. G., Bastelberger, S., Mousavi-Fard, M., ... & Nenes, A. (2017). Revising the hygroscopicity of inorganic sea salt particles. Nature communications, 8, 15883.

Ward, P. J., and P. J. DeMott (1989), Preliminary experimental evaluation of Snomax (TM) snow inducer, nucleus Pseudomonas syringae, as an artificial ice for weather modification, J. Weather Modif., 21(1), 9-13.

Welti, A., Liiond, F., Stetzer, O., and Lohmann, U. (2009) Influence of particle size on the ice nucleating ability of mineral dusts. Atmos. Chem. Phys., 9, 6705-6715.

Woodley, W.L., and T.J. Flenderson (1990) "Atmospheric Tests of an Organic Nucleant in a Supercooled Fog", J. Weather Mod., 22: pp. 127-132.

Claims

1. A cloud seeding method characterized by that the cloud seeding agents that are demanded for its application are natural ice nucleating agents either of plant or mineral origin, active at the temperature range between -5 °C and 0 °C.

2. A method according to claim 1 wherein the natural ice nucleating agents of plant origin are derived from a plant or plant part belonging in the order of Rosales preferably in the family of Elaeagnaceae and the genus Hippophae.

3. A method according to claim 2 wherein the natural ice nucleating agents of plant origin are derived from the plant Hippophae rhamnoides, or part of it, or product thereof.

4. A cloud seeding method characterized by that the cloud seeding agents that are demanded for its application are natural ice nucleating agents of mineral origin, active at the temperature range between -5 °C and 0 °C.

5. A method according to claim 4 characterized by that the natural ice nucleating agents of mineral origin which are silicate minerals.

6. A method according to claim 5 characterized by that the natural ice nucleating agents of mineral origin are silicate minerals of the tectosilicates group like feldspar, nepheline, petalite, leucite, sodalite, cancrinite, scapolite, analcite and zeolite.

7. A method according to claim 5 characterized by that the natural ice nucleating agents of mineral origin are silicate minerals of the cyclosilicates group like tourmaline.

8. A method according to all above claims characterized by that the natural ice nucleating agents of mineral or plant origin of the present invention are used in a mixture with other known ice nucleating agents like alcohols and salts, in order to increase their effectiveness in cloud seeding.

9. A method according to claims 1-8 characterized by that the cloud seeding is intended to the suppression or the restriction of hailfall.

10. A method according to claims 1-8 characterized by that the cloud seeding is intended to the induction of artificial rainfall.

11. A method according to claims 1-8 characterized by that the cloud seeding is intended to the induction of artificial snowfall.

12. A method according to claims 1-8 characterized by that the cloud seeding is intended to the restriction or to the elimination of fog.