THE idea of getting the rain to fall used to be the stuff of myth, legend or science fiction. The classic tale is of a shaman performing a ritual to summon rain to fall to quench the thirst of a parched land.
In science fiction, the idea was known as weather manipulation. Technology, not religious mumbo-jumbo, became the key to extracting enough moisture from the sky to make it rain.
Cloud seeding, as a practical tool for weather manipulation, was discovered accidentally in 1946 in the United States. Seventy years later, it is now considered a statistically reliable tool to increase precipitation in areas in need of moisture.
In the Philippines it has been used as constant institutional tool to deal with the effects of long dry spells or drought.
The first thing that comes to mind when one reads about cloud seeding is that it should produce rain. And when such efforts produce no rainfall, the automatic reaction was that it failed.
It’s not that simple.
“ONE thing that people have to consider is the evaporation rate,” Thelma A. Cinco of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said. Cinco’s office comes up with climate-assessment reports that are designed to help the agricultural industry to adapt to changing climate conditions.
“You have a limited supply of water for consumption,” explained Cinco, head of the Pagasa Impact Assessment Application Section, Climatology and Agronometerology Division. “To make it last, you ration the water. But it’s not just consumption. There’s also evaporation to consider.”
“For example, the evaporation rate for a given area is 5 millimeters [mm] per day. To maintain an ample amount of moisture in that area, it must receive an average of 150 mm of rainfall per month,” she said. “But that’s assuming there is still moisture in the area.
During a drought, the problem is that there is no longer moisture in that area.”
When drought impacts the water supply, crop failure and reduced irrigation occurs. However, the drought’s effect is not confined to the agricultural industry.
The reduced water supply will result in less water for domestic use and adversely affect electrical production from hydropower sources.
CINCO explained that the drought and dry spell currently prevailing in Mindanao is comparable to the effects of El Niño that hit the country in 1998.
Records show during that year, water shortage in hydropower facilities reduced power generation to just 34.61 gigawatt-hours (GWh), down from the previously recorded 10-year average of 133.59 GWh. This was a staggering 74.1-percent reduction, resulting to power outages of several hours in Mindanao. Many expressed fears these outages will occur anew.
At present, publicly available records show that the Mindanao electrical grid has a capacity to generate 1,445 megawatts (MW). However, the recorded peak demand for electricity is 1,458 MW. The generating capacity is short by 13 MW.
The deficit may increase with the onset of summer. “The El Niño effects will persist, most probably until June,” Cinco said.
This means the priority for cloud-seeding operations are water-catchment areas, such as dams and lakes, because they both serve as the sources for hydropower, irrigation and water for human consumption.
Ma. Cecilia Monteverde, the weather bureau’s technical supervisor for its cloud-seeding project, agreed with the assessment.
This is where cloud seeding becomes a vital part of the drought and dry-spell mitigation effort, according to Monteverde.
“The first principle in cloud seeding is the presence of seedable clouds that can generate rainfall,” she explained. “Even if you have the seeding materials and there are no seedable clouds, we cannot generate rainfall. These seeding materials cannot form a cloud that can produce rain.”
PAGASA Cloud Seeding Project Coordination Officer Lorenzo A. Moron said “conditions must be favorable in order to produce rainfall.” “When conditions are favorable, the seeding materials enhance rainfall,” Moron added.
“Clouds contain moisture,” Monteverde said. “However, not all clouds contain enough moisture to form rainfall that reaches the ground. The seeding materials are used to generate enough moisture to form large enough particles for rainfall that can reach the ground.”
Moron cited as example their recent cloud-seeding project in Zamboanga. “If the climate is hot enough, the rainfall evaporates before reaching the ground,” Moron explained. “That’s what happened in Zamboanga. The heat evaporates the precipitation on the way down.”
Moron pointed out that the best period to conduct cloud-seeding operations is before the onset of the dry spell or drought.
“Any cloud-seeding operations conducted after that can produce some rainfall, but the moisture available will not be enough,” he added.
“Our cloud-seeding operation is not a full-blown operation in nature,” Monteverde said. “We are under a science agency, so we focus on research to improve the methodology for cloud-seeding operations conducted by the BSWM [Department of Agriculture’s Bureau of Soil and Water Management], which is the mandated agency.”
MORON considered their attempt at Zamboanga as “not a total failure nor was it a total success.”
“The cloud-seeding operation did produce rainfall. Unfortunately, the rainfall occurred outside the target area,” he said. “It may not have provided a significant increase of water for the watershed, other people still benefited from the rain.”
Water-catchment areas and watersheds are areas that Pagasa targets for its cloud-seeding operations. “Other sectors are a second priority for our operations,” Moron explained. “The [DA-BSWM] is the lead agency for conducting cloud-seeding operations focused on agricultural areas.”
Monteverde then emphasized the biggest drawback in all cloud-seeding operations.
“Even if a cloud-seeding operation is well-funded, if there are no seedable clouds, no rainfall can be produced,” she warned.
“That’s why cloud-seeding operations must be approached through a scientific matter,” Moron said. “We use various tools to determine the presence of ‘seedable’ clouds in a target area.”
He added that a “seedable” cloud arrives only after “several days.”
These scientists look for low lying cumulus convective clouds. Once such a cloud is spotted, the cloud-seeding aircraft then disperses a seeding material into the cloud. This is usually iodized salt.
PAGASA, the government’s weather-monitoring agency, is now testing a new type of seeding material to improve the effectiveness of cloud-seeding operations in the Philippines.
“We are now testing a new type of salt,” Monteverde said. “Before, we used iodized salt. The new type is more of a powder because the finer the salt, the more moisture it can attract.”
“This new type is more buoyant in the air, giving in more time to attract more moisture in the atmosphere,” Moron added. “We can seed a larger area with 1 gram of the new powdered salt compared to 1 gram of the standard
Monteverde explained that this new powdered salt has an additive to prevent it from clumping together, which helps maintain its powdery form.
Both Monteverde and Moron expressed confidence that Pagasa’s efforts will pay off by increasing the amount of rainfall produced in cloud-seeding operations.
“Science is a work in progress,” Monteverde said. “We always look at data to find out which method works best. This is an investment. We find out what works best and turned that method over to the BSWM.”
Aside from research and development, the scientists and technical experts of the weather bureau play another crucial role for cloud-seeding operations.
“We determine if conditions are favorable for the conduct of cloud-seeding operations,” Monteverde said.
“We use Doppler radar, upper air soundings, and other tools to detect and monitor the movement of potential seedable clouds,” Moron added.
DESPITE unfavorable conditions, Moron said the weather bureau went ahead with the cloud seeding in Zamboanga, which was held in February.
“For Zamboanga, based on climatology and climate records, there is really very little rain there during February,” he said. “It’s really dry and unfavorable for cloud- seeding operations.
However, since it was an urgent request, we went ahead and used the opportunity to conduct further research and tests during the cloud-seeding operation.
Despite the unfavorable conditions, we were still able to generate some rainfall.”
At least, according to him, the cloud-seeding operations provided relief, “especially when the target area is a dam, because a dam can store rainfall.”
He also explained the reality when cloud-seeding operations are conducted in agricultural areas, especially over upland farms.
“For agricultural areas, cloud- seeding operations provide temporary relief, because the water easily evaporates,” Moron pointed out.
There was one other beneficial effect that can occur even if a cloud-seeding operation does not produce rain.
“One other point for cloud-seeding is this: Even in instances that rainfall is not produced, cloud-seeding operations can lower the temperature to slow down evaporation,” Monteverde explained. “That is one positive impact.
The seeded clouds tend to grow bigger. Bigger clouds over bodies of water help reduce the rate of evaporation.”
MONTEVERDE admitted “sometimes cloud-seeding operations over Angat Dam do not produce rainfall.”
“However, it was established that after the cloud-seeding operation, the rate of evaporation in the dam fell, helping the dam to sustain its water supply longer.”
Moron explained, “The general objective of cloud seeding is to augment freshwater resources.”
“And when we talk of freshwater resources, it is used for multiple activities,” Moron said. “[This resource is not only for domestic consumption, it is also for commercial and industrial purposes, such as agriculture and power generation.”
“Cloud-seeding operations must be multipurpose in approach,” he said. “We should not be conducting cloud-seeding operations solely to have water to drink. Cloud seeding is meant to increase freshwater resources for multiple uses and activities.”
“Cloud-seeding operation is not a guarantee that we will produce actual rainfall, because conditions vary from place to place,” Monteverde added. “We, in Pagasa, are conducting research to determine the best conditions to help enable the present technology available to work efficiently.”