Assessment of the Cloud Seeding Efficiency over Tom Green County Texas, USA

Abstract

The efficiency of cloud seeding in enhancing precipitation is a subject of active debate within the scientific community. This work examines the impacts of cloud seeding in changing cloud properties and dynamics over Tom Green County in West Texas, USA, from 2015 to 2020. Several cloud categories including small, large, and type B are considered. The effect of cloud-seeding missions in changing clouds’ lifetime, area, volume, and precipitation mass is investigated. The results show that the average increase in the lifetime of small, large, and type B is 53.6, 27, and 3.5%, respectively, while the average area increased by 47.1, 27.5, and 5.0% respectively, and their average volume increased by 63.6, 33, and 5.6% respectively. A significant increase in the precipitation mass of the small, large, and type B clouds is observed after the seeding missions. From 2015 to 2020, the precipitation rates in seeded clouds are higher than the unseeded clouds. Comparing precipitation rates during the 2015–2020 cloud-seeding campaigns to the period from 2010 to 2014 before the campaigns shows no trend of increasing precipitation except during 2015 and 2016.

1. Introduction

Cloud seeding is a weather modification technique aimed at enhancing precipitation in clouds by introducing substances that act as ice nuclei (IN) or cloud condensation nuclei (CCN) [1]. This process involves dispersing materials, such as silver iodide or dry ice, into clouds to stimulate the formation of ice crystals or water droplets, ultimately increasing rainfall or snowfall.

Cloud seeding as a weather modification technique has been a subject of scientific exploration for several decades evolving from early experiments to government-supported programs and regional initiatives. Traced back to the early 20th century [2] when pioneering scientists began investigating the possibility of influencing weather patterns. Throughout its development, cloud seeding has showcased potential benefits for water resource management and precipitation enhancement. The most important and notable initial experiments in this field are Vincent Schaefer’s experiments in 1946 [3], which involved seeding clouds with dry ice to initiate snowfall, and Irving Langmuir and Vincent Schaefer’s collaboration in 1946 [3], leading to the discovery of super-cooled clouds and the impact of seeding on precipitation. Cloud-seeding operations have seen notable advancements and increased implementation over the past two decades. During this period, there has been a growing focus on utilizing cloud seeding to address water resource management, enhance precipitation, and mitigate the impacts of drought.

Governments worldwide recognized the potential of cloud seeding and initiated programs to explore its applications. Previously, the United States (US) Weather Bureau (now NOAA) initiated Project Cirrus in 1947 [4], aiming to investigate cloud modification through seeding. Followed by the National Hail Research Experiment (NHRE) conducted in the 1970s by multiple US agencies to study hail suppression techniques [4].

To address water resource management and precipitation enhancement, cloud seeding has been extensively studied and implemented in various regions around the world (Figure 1), including the United States (US) [5], China [6], and the Middle East (ME) [7]. For example, the Colorado River Basin Cloud-Seeding Program was initiated in the 1950s to augment water supply for agricultural and municipal purposes. Moreover, many cloud-seeding campaigns have been launched in arid regions in the United Arab Emirates (UAE) [8], Saudi Arabia (sKSA) [9], and China [10].

These programs aim to increase water resources and alleviate water scarcity issues through targeted cloud-seeding efforts. In addition, advancements in cloud-seeding techniques, such as the use of ground-based generators and aircraft systems, have improved the efficiency and effectiveness of the process. Ongoing research and evaluation are being conducted to better understand the environmental impacts and optimize the outcomes of cloud-seeding operations. Overall, cloud seeding has become an increasingly important tool in the quest for sustainable water management and addressing water-related challenges.

Given the challenges posed by climate change, cloud seeding is increasingly being adopted as a technique to manage water resources in regions with increased drought conditions (e.g., Saudi Arabia, Australia). In Australia, prolonged droughts have affected agriculture and water supplies, leading to significant economic impacts [11]. The USA faces similar challenges, especially in the West, where states like California experience severe droughts that threaten water security and agriculture [12]. In China, droughts have affected the Yangtze River basin, crucial for irrigation and hydropower, prompting governmental interventions to manage water resources more effectively [13]. Meanwhile, the UAE and Saudi Arabia grapple with arid conditions and rely heavily on desalination and groundwater extraction to meet water needs, with the region’s limited rainfall exacerbating drought risks [14].

Tasmania, Australia, has been experimenting with cloud seeding since the 1960s [15]; reports [6] state that the efforts of cloud-seeding enhancement have been raising rainfall by 5–14%.

China has been actively engaged in cloud-seeding operations to address water scarcity and enhance precipitation [10,16]. As one of the world’s largest users of cloud-seeding technology, China has implemented extensive programs across various regions. For instance, the country has focused on cloud seeding in arid areas, such as the northwestern provinces, to combat drought and increase water resources. China’s cloud-seeding operations have involved the deployment of aircraft or ground-based generators to disperse cloud-seeding agents [10], primarily silver iodide, into targeted clouds. While specific data on the outcomes of these operations may vary, studies have indicated that cloud seeding in China has contributed to notable increases in precipitation. Henan region [6] operation recorded a 12.8–13.8% increase in rainfall, and the Fujian Gutianin region operation recorded a 24.16% increase in rainfall [6].

Cloud-seeding operations in the Middle East (ME) have gained significant attention as countries in the region face water scarcity challenges. The ongoing commitment to cloud seeding in the ME demonstrates the region’s dedication to sustainable water management and addressing water scarcity challenges. The United Arab Emirates (UAE) and Saudi Arabia (KSA) have implemented cloud-seeding programs to increase rainfall and enhance water resources. The ME’s arid climate makes cloud seeding a valuable tool in addressing water shortages and supporting agricultural activities.

In the UAE, the National Center of Meteorology (NCM) has been actively involved in cloud-seeding initiatives since the early 2000s [8]. The country employs aircraft and ground-based generators to disperse cloud-seeding agents, primarily using silver iodide, into suitable clouds [4]. While the effectiveness and precise impact of these operations vary depending on weather conditions, studies have reported positive results, including increased rainfall and improved water availability [4]. Research conducted by the NCM and other institutions has indicated an increase in precipitation ranging from 5 to 30% in targeted areas [17]. UAE has been at the forefront of cloud-seeding efforts, utilizing advanced techniques to enhance precipitation and address water scarcity [4]. Recognizing the importance of water resources in sustaining various sectors of the economy, the UAE has invested significantly in cloud-seeding programs. Cloud seeding in the UAE has particularly focused on enhancing rainfall during the country’s rainy season, which typically occurs between November and March [8]. By actively leveraging cloud-seeding technology, the UAE demonstrates its commitment to sustainable water management, ensuring a more reliable water supply for agriculture, domestic use, and other vital sectors [4].

In KSA, cloud seeding is an important tool to enhance precipitation and mitigate water scarcity. The first experiment of Saudi Arabia Cloud Physics (SACPEX) was conducted in 1990 by the University of Wyoming in the Asir region [18]. The country has implemented significant cloud-seeding programs to increase rainfall and improve water resources [7]. The Saudi Ministry of Environment, Water, and Agriculture oversees these initiatives, working in collaboration with research institutions and international partners [19]. The Kingdom utilizes aircraft and ground-based generators to disperse cloud-seeding agents, primarily silver iodide, into clouds [20,21]. This process aims to stimulate the formation of ice crystals and subsequently enhance precipitation. While specific data on the outcomes of cloud seeding in KSA may vary, studies have shown promising results [7].

The effectiveness of cloud-seeding techniques can vary depending on meteorological conditions such as cloud type, temperature, and moisture content. It is challenging to accurately predict and control these conditions, leading to inconsistent results [17]. Over the past decades, these techniques have been implemented and studied in various regions of the world.

Cloud seeding and ice nucleation aim to increase precipitation by influencing droplet or ice crystal formation. By introducing hygroscopic particles in warm clouds, cloud seeding increases the number of droplets, leading to enhanced coalescence and, ultimately, precipitation. In cold clouds, ice nucleation leads to rapid freezing, increasing the concentration of ice crystals and resulting in enhanced precipitation rates [1]. Artificial seeding modifies cloud optical properties by changing the size, concentration, and phase of cloud particles. By enhancing droplet or crystal size, seeding affects cloud albedo, which impacts the cloud’s ability to reflect solar radiation. This property is important in climate models, as clouds with higher albedo have a cooling effect by reflecting more sunlight, while clouds with lower albedo have a warming effect [22]. By altering the microphysical properties of clouds, seeding and nucleation can impact cloud lifetime. Hygroscopic seeding can increase the number of large droplets, which hastens the onset of precipitation and reduces cloud longevity. In contrast, ice nucleation may lead to the rapid glaciation of supercooled clouds, shortening their lifetime [23].

Ice nuclei (IFN) and hygroscopic aerosols can invigorate cumulus clouds and influence rainfall. Seeding clouds with ice-forming nuclei like silver iodide (AgI) may increase cloud height and rainfall by releasing latent heat when droplets freeze, though large-scale trials show inconsistent results. High concentrations of cloud condensation nuclei (CCN) also impact cloud dynamics by creating numerous droplets that reach supercooled levels and freeze, boosting updrafts and rainfall, especially in warm maritime environments. A prominent mechanism, termed “condensational invigoration,” occurs when pollution-sized aerosols create many small droplets with high surface areas, enhancing condensation, latent heat release, and rainfall. This mechanism appears to be the main driver of aerosol-induced cloud invigoration in polluted settings.

Cloud seeding with silver iodide is a commonly used technique in weather modification [16]. Silver iodide particles are dispersed into clouds either by ground-based generators or by aircraft [6]. These particles serve as ice nuclei, which facilitate the formation of ice crystals within the cloud. As a result, the ice crystals can grow and eventually fall as precipitation, enhancing rainfall or snowfall.

Hygroscopic flares involve the use of flares containing hygroscopic materials, such as potassium chloride or sodium chloride [4]. These flares are ignited in the lower part of clouds, releasing the hygroscopic particles [24]. The particles absorb moisture from the cloud, causing the cloud droplets to grow and potentially leading to increased rainfall.

Cloud seeding has evolved into a potential solution to water scarcity, a tool for weather modification, and a method for forest fire fighting.

In this study, we are examining the effectiveness of cloud-seeding missions in increasing precipitation and affecting cloud properties from 2000 to 2015 over West Texas, United States.

This study explores the efficacy of cloud seeding over Tom Green County [25], Texas, and contributes new insights into the impact of seeding on different cloud properties, such as lifetime, area, volume, and precipitation levels. Unlike prior analyses that largely provided general assessments of precipitation enhancement, this work offers a nuanced breakdown by specific cloud types (small, large, and Type B clouds) and examines distinct physical responses to seeding operations. The findings highlight how cloud seeding produces varied effects across these cloud categories, emphasizing that smaller clouds demonstrate more pronounced changes in both volume and precipitation mass relative to larger cloud formations. This detailed categorization and comparison fill an important gap left by earlier studies, which did not differentiate cloud responses by type. Moreover, the study leverages recent data (2015–2020), advancing our understanding of long-term seeding effects in this region and potentially informing future seeding protocols under comparable meteorological conditions [26].

2. Study Area

San Angelo, TX, USA, located within Tom Green County (Figure 2), is characterized by a diverse and picturesque topography that includes meandering rivers, undulating hills, and expansive plains. This unique landscape provides an ideal setting for cloud-seeding operations aimed at enhancing precipitation levels in the region. The topography of Tom Green County plays a crucial role in influencing local weather patterns, with elevation changes and geographic features contributing to the dynamics of cloud formation and rainfall distribution.

The weather conditions in San Angelo exhibit distinct seasonal variations, with hot and dry summers contrasting and mild winters [27]. These climatic conditions create opportunities for cloud-seeding initiatives to address water scarcity challenges and support agricultural activities in the area by strategically deploying hygroscopic flares and glaciogenic flares [1], which has demonstrated significant improvements in precipitation levels and water resource management.

In Tom Green County, cloud-seeding efforts involve dispersing various particles into clouds to enhance rainfall. The goal of this process is to encourage precipitation and reduce the effects of drought in the area. These cloud-seeding initiatives aim to strengthen the local water supply and support agricultural activities, particularly during dry periods. Scientists and meteorologists work to stimulate raindrop formation and improve precipitation odds. This proactive approach highlights the community’s dedication to effectively managing water resources and maintaining agricultural productivity, underscoring Tom Green County’s commitment to innovation and environmental stewardship [28].

3. Method

Cloud-seeding operations were conducted over Tom Green County, targeting cloud systems during March–October from 2015 to 2020. Seeding agents included silver iodide particles and hygroscopic salts, delivered either via aircraft or ground-based generators, depending on cloud accessibility and wind conditions. Specific details of the campaigns include annual campaigns consisted of 21 to 38 operational days, with seeding missions conducted under conditions favorable for precipitation enhancement. The number of seeded clouds each year varied from 54 to 111, focusing on those with suitable moisture levels and structural characteristics as identified through satellite-based precipitation measurements.

In this work, a Global Precipitation Measurement (GPM) [29] satellite product is used to analyze precipitation patterns over San Angelo, TX, USA, after cloud-seeding missions to assess their efficiency in enhancing precipitation. GPM is an international initiative aimed at improving our understanding of global precipitation patterns and their impact on Earth’s water cycle [29]. Launched on 27 February 2014, GPM is a collaboration between NASA and the Japan Aerospace Exploration Agency (JAXA), with contributions from other international partners. The mission utilizes a constellation of satellites and ground-based sensors to provide high-quality global precipitation data [29]. To accurately measure precipitation, GPM employs a dual-frequency precipitation radar (DPR) and a microwave imager (GMI) aboard the GPM Core Observatory satellite [29]. The DPR is capable of providing detailed three-dimensional measurements of precipitation particles, while the GMI detects microwave radiation emitted by precipitation [30]. These instruments work together to provide comprehensive and precise information about the distribution, intensity, and structure of precipitation systems worldwide [31,32].

GPM precipitation products have a wide range of applications and benefits in various fields. For instance, in weather forecasting, GPM data plays a crucial role in improving precipitation estimates and enhancing the accuracy of weather models [33]. By providing real-time and accurate information about rainfall rates and storm intensities, GPM enables meteorologists to issue more reliable and timely forecasts, enhancing early warning systems for severe weather events [29]. Furthermore, GPM data are invaluable for hydrological studies such as drought monitoring [34], water management [35], and extreme precipitation analysis [36]. They contribute to a better understanding of the water cycle, including the processes of evaporation, condensation, and precipitation. By monitoring global precipitation patterns, GPM helps researchers assess changes in rainfall distribution, which is essential for studying climate variability and long-term climate trends [29].

In this study, we focused on the Level 3 Integrated Multi-satellite Retrievals for the GPM (IMERG) product, which is intended to intercalibrate, merge, and interpolate satellite precipitation estimates, precipitation gauge analyses, and other potential precipitation data sources at fine spatial and time scales [37]. The GPM IMERG products can be directly downloaded on NASA’s website (https://gpm.nasa.gov/data/directory accessed on 5 December 2024) with fine spatial (0.1° × 0.1°) resolution and various temporal resolutions (from half-hourly to monthly). IMERG products are distributed in three different time scales based on the applied calibration: the near-real-time “Early” run, the “Late” run product, and the post-real-time “Final” run product. The IMERG “Early” run and the “Late” run products are released about 4 h and 12 h after the observation time, respectively, while the IMERG “Final” run product is released about 3.5 months after the observation month through the climatological correction with the Global Precipitation Climatology Centre (GPCC) precipitation gauge analysis [30]. In this study, we implemented the daily “Final” IMERG product (product name: GPM_3IMERGDF).

The GPM IMERG Level 3 product data were used in this study to determine precipitation patterns, while key parameters related to clouds were acquired during the cloud-seeding operations. Those cloud parameters are the cloud lifetime, area, and volume as well as the precipitation mass, which were reported after each seeding operation [38,39,40,41,42,43,44,45,46,47,48], noting the duration from formation to dissipation. The cloud parameters were calculated based on Thunderstorm Identification, Tracking, Analysis, and Nowcasting (TITAN) [49] and NEXRAD [50] data. To assess the effects of cloud seeding, we compared these metrics pre- and post-seeding, applying statistical analysis to detect significant changes in cloud properties and their potential influence on precipitation efficiency. This robust approach provided a detailed understanding of how cloud seeding may alter cloud dynamics and enhance precipitation. In particular, the volume and area of the seeded cloud and its lifetime were detected before and after the seeding agent’s injunction to report the changes in cloud physical properties and water content during operations for the three cloud classifications. The three cloud clusters are named as small (S), large (L), and type B (B) clouds and are defined based on their average area of ~1.4, ~52.5, and ~96.7 km², respectively, and their average volume of ~4.8, ~248.3, and ~393.0 km³, respectively. The percentage of change was calculated for each component during the operations and the average change over the period of cloud-seeding activities.

4. Results and Discussion

Since 2015, there have been many cloud-seeding operations reported and evaluated in San Angelo, TX, USA [30] (

Table 1. Cloud-seeding campaigns (2015–2020) in San Angelo, TX, USA. Showing the number of clouds that were seeded, days per year, and the annual rain enhancement percentage [38,39,40,41,42,43,44,45,46,47,48].

Year	#Clouds	#Days	% Increase in Rainfall
2015	88	38	10
2016	111	32	9
2017	73	24	10
2018	54	21	12
2019	61	31	18
2020	56	27	20

). It can be shown that the percentage of rainfall increase ranges between 9 and 20%.

The percent change in precipitation is recorded after several cloud-seeding campaigns from 2015 to 2020 in the Tom Green Country, Western Texas, for small, large, and type B clouds (

Table 2. Precipitation amount and enhancement percentage by cloud-seeding operations in Tom Green County, West Texas, from 2015 to 2021, for three cloud classifications: small clouds, large clouds, and type B clouds. Y: Seeding scenario, N: No seeding scenario.

Year	Scenario	Type of the Cloud
		Small		Large		Type B
		Precipitation
	Seeding	Increasing Percent (%)	Amount	Increasing Percent (%)	Amount	Increasing Percent (%)	Amount	Total
			mm		mm		mm	mm
2015	Y	135	26.024	89	126.99	10	79.2	232.22
	N		11.074		67.19		72.00	150.27
2016	Y	125	23.40	58	113.05	7	71.84	208.29
	N		10.40		71.55		67.14	149.09
2017	Y	115	22.62	40	122.85	8	72.90	218.37
	N		10.52		87.75		67.50	165.77
2018	Y	150	32.50	79	114.88	19	47.60	194.98
	N		13.00		64.18		40.00	117.18
2019	Y	105	33.58	64	114.67	7	214.00	362.25
	N		16.38		69.92		200.00	286.30
2020	Y	120	17.68	43	104.09	9	93.26	225.03
	N		12.58		72.79		85.56	170.93

and Figure 3a,b).

Across the six-year period, seeded clouds consistently exhibited higher precipitation rates than unseeded clouds. Small clouds (S) experienced the highest average increase in precipitation, ranging from 105% to 150% annually, followed by large clouds (L), with increases between 40% and 89%. Type B clouds showed the least enhancement, with precipitation increasing from 7% to 19%. This variability suggests that cloud seeding is particularly effective in enhancing precipitation in smaller cloud systems (Table 2, Figure 4). The average increase in lifetime was substantial in small clouds, peaking at 75% in 2018, compared to 32% for large clouds and only 3–6% for type B clouds. This indicates that seeding more significantly prolongs the duration of smaller cloud systems, potentially contributing to the higher precipitation increases observed in these clouds (Figure 5a). Similar to lifetime, cloud area and volume showed the most significant growth in small clouds, with area increases up to 57% and volume increases up to 88%. Large clouds displayed moderate increases in area and volume (up to 37% and 48%, respectively), while type B clouds exhibited minimal changes in both properties. This finding aligns with the limited precipitation enhancement in type B clouds, suggesting that the effect of seeding is more pronounced in clouds with a smaller pre-seeding volume and area (Figure 5b,c).

While each year showed a positive effect from seeding, the magnitude of these effects varied. For example, 2018 and 2019 saw peak increases in precipitation for small clouds, potentially due to favorable meteorological conditions that complemented the seeding operations. Additionally, certain weather factors, such as moisture content and wind patterns, may have influenced these results, suggesting that seeding effectiveness depends not only on cloud type but also on annual climate variability. The differential impact across cloud types highlights the role of initial cloud conditions, particularly cloud size and moisture content, in determining seeding efficacy. Small clouds, with their relatively modest initial volume, appear more responsive to seeding agents, which likely leads to enhanced nucleation and precipitation outcomes. Conversely, type B clouds, with larger initial volumes, show limited response, underscoring that cloud-seeding efficiency may diminish in larger more robust cloud systems (Figure 5d).

The observed variability in precipitation increases rates among cloud types and across years; the interaction between cloud-seeding agents and cloud properties is complex and influenced by local meteorological conditions. This finding reinforces the existing literature that seeding effects are more pronounced in smaller cloud systems, which may provide a more conducive environment for nucleation processes. Further research is recommended to evaluate how specific environmental factors such as wind and humidity influence seeding outcomes across different cloud types and regions.

Figure 5d illustrates the variability in cloud percent mass due to cloud seeding over Tom Green Country from 2015 to 2020. A significant enhancement in the clouds’ precipitation mass can be observed from 2015 to 2020 for seeding missions of the S, L, and B. The precipitation mass of the S clouds increased from 2016 kton in 2015 to 3609.9 kton in 2020, the precipitation mass of the L clouds increased from 66,701 kton in 2015 to 304,105 kton in 2020, and the precipitation mass of the B clouds increased from 222,340 kton in 2015 to 538,331 kton in 2020.

Figure 6 illustrates data from the GPM satellite of the annual area average precipitation rate (mm/h) over Tom Green County before and after the start of the seeding campaigns in 2015. It can be observed that precipitation rates increased in 2015 and 2016, then declined to pre-2015 precipitation rates. This indicates that increasing clouds’ precipitation mass is not always correlated with the precipitation rate as other meteorological conditions could control the precipitation rates.

5. Conclusions

Cloud seeding is a microclimate modification technique aimed at increasing precipitation in freshwater scarcity areas. Cloud seeding operates on the principle of improving the process of rain formation within clouds by using substances that can enhance the formation of droplets and ice crystals within clouds. The process relies on the principle of nucleation by providing additional particles around which water droplets can condense, enhancing the probability of forming larger droplets that can fall as rain or snow. This technique is based on the fact that water vapor requires a surface to condense onto. The seeded particles can enhance the condensation process, turning water vapor into water droplets, which then grow by collecting more moisture and eventually fall due to gravity. The most common technique involves spraying substances known as cloud condensation nuclei (CCN) into the clouds. Silver iodide and sodium chloride are among the substances that are frequently used for cloud seeding (DRI 2023). Cloud seeding has been adopted in many countries including the United States, China, Australia, and the Middle East. Despite its potential to supplement water sources in drought-stricken areas, the efficiency of the technique is still debatable, and its environmental effects require further research to assess its effectiveness and viability.

This study investigates the efficiency of cloud seeding in modifying clouds’ physical properties and their precipitation rate. Small, large, and type B clouds were seeded over Tom Green County in Texas, United States, and the overall changes in the clouds’ lifetime, area, volume, and precipitation mass were measured from 2015 to 2020. Additionally, precipitation rates are compared between seeded and unseeded clouds during the cloud-seeding campaign. Meanwhile, precipitation rates during the seeding mission from 2015 to 2020 are compared with those from 2010 to 2014 before the seeding missions.

Cloud seeding is most effective in modifying the physical properties of the small clouds, while least effective in modifying the physical properties of the type B clouds. This could be attributed to clouds’ pre-seeding area, volume, and height. All cloud-seeding techniques including airplane dispersion, launching rockets into the cloud, and ground-based dispersion can usually target limited spatial regions, and its effect will be more noticeable with small clouds.

This study found that seeded clouds have higher precipitation rates than unseeded clouds; however, a long-term pattern does not show a specific trend of increasing precipitation because of the cloud seeding. Despite the fact that cloud seeding can effectively modify clouds’ physical properties and lifetime, it cannot always increase the clouds’ precipitation rates. This is because the success of the seeding missions also depends on local meteorological conditions. For instance, the clouds’ water contents are important, as cloud seeding is more effective with clouds that have an adequate level of moisture. Wind conditions are also important as the wind can blow out the seeding agent away from the cloud before the seeding process takes place. Thus, for cloud seeding to be effective, the meteorological conditions must align to enable the process, with adequate moisture levels and favorable wind patterns being key elements.

The broader implications of cloud seeding observed in this study suggest potential impacts on climate, air quality, and public health. Enhanced precipitation in seeded areas could influence local climate stability by potentially moderating temperatures and alleviating drought conditions, which in turn can support agriculture and water supply reliability. However, increased precipitation also poses environmental considerations, such as changes in soil moisture and potential downstream effects on neighboring ecosystems. Regarding air quality, cloud seeding involves dispersing aerosols, like silver iodide, into the atmosphere, which could affect air quality depending on dispersion rates and concentrations. While these materials are used at controlled levels, further research could explore the cumulative impact of such particles on air quality and potential respiratory health outcomes in nearby populations. Addressing these broader impacts will be important to ensure that cloud-seeding practices are both effective and environmentally sustainable for regional health and climate resilience. Further research on seeding impact on cloud vertical motion considering field winds is suggested to assess seeding efficiency on changing cloud properties.

Ethical aspects regarding the intentional modification of weather patterns should be taken into consideration as they can have consequences for other countries or ecosystems.

It can be observed that precipitation amounts increased by ~105–150%, 40–89%, and 7–19% for small, large, and type B clouds, respectively, over Western Texas from 2015 to 2020.

While its effectiveness remains a topic of debate, there is evidence suggesting that cloud seeding can enhance precipitation under certain meteorological conditions.

Research conducted by the National Center for Atmospheric Research (NCAR) in the USA has indicated that cloud seeding can increase precipitation by 5−15% in targeted areas. The World Meteorological Organization (WMO) recognizes cloud seeding as a viable technology for weather modification but emphasizes the need for rigorous scientific studies and careful evaluation of its environmental and societal impacts.

Over the years, advancements have been made in cloud-seeding techniques and materials used. Some notable developments include the introduction of silver iodide as a common cloud-seeding agent due to its ice-nucleating properties, the development of ground-based generators and aircraft systems for dispersing cloud-seeding agents, and the use of hygroscopic materials (e.g., potassium iodide) is used in cloud seeding to enhance rainfall, highlighting the importance of considering regional topography and weather conditions in weather modification practices [16]. Cloud-seeding operations in Tom Green County aim to stimulate cloud development, enhance precipitation, and mitigate the impact of droughts on the local ecosystem [28].