Cloud seeding may not be as promising for drought-troubled countries as they hope

Colorado has many mountain peaks. To ignite chemicals into the clouds, machines are set up.attempts to create snow. This is known as cloud seeding. As global temperatures rise, more of this process will be possible. Countries States that are suffering from droughtThey use it in desperate attempts to change the weather.

But cloud seeding isn’t as simple as it sounds, and it might not be as promising as people wish.

As an Atmospheric scientistI have also studied and Weather modificationFor 50 years. Cloud seeding Snow and rain are produced by experimentsThe following are required Right type of cloudsWith enough moisture and the right temperatures and wind conditions. The percentage increases in precipitation are small, and it’s difficult to tell when snow or rain fell naturally and when it was triggered by seeding.

How modern cloud seeding was started

The 1940s saw the dawn of modern weather modification in Schenectady (New York).

Vince Schaefer is a scientist at General Electric. A small amount of dry-ice pellets was enough to make a difference. to a freezer containing “supercooled” water droplets triggered a proliferation of ice crystals.

Other scientists also believed the same.The right mixture of supercooled water drops, ice crystals and water could cause precipitation. Snow formsWhen ice crystals stick together in clouds. Scientists argued that ice-forming particles could be added into clouds to increase the chance of moisture vaporizing. Schaefer proved that it was possible.

On Nov. 13, 1946, Schaefer Drop crushed dry iceFrom a plane to supercooled stratus clouds “I looked toward the rear and was thrilled to see long streamers of snow falling from the base of the cloud through which we had just passed,” He wrote in his journal. He wrote a few days later that the same technique seemed to have improved visibility in fog.

Bernie Vonnegut (GE colleague) searched chemical tables for materials that had a crystallographic structure like ice. A smoke of silver iodide particleCould have the same effect at temperatures below 20 C (-4 F) than dry ice.

Their research led them to Project Cirrus, a joint civilian/military program that explored seeding a variety cloud types, including supercooled stratus clouds and cumulus cloud. even hurricanes. Within a few years, companies and communities that depend on water spent US$3 million to 5 million per year on cloud-seeding projects. This was especially true in the drought-prone western U.S. According to testimony of Congress in the 1950s.

But does cloud seeding really work?

The results of more than 70 years of research on the effectiveness of cloud seeding are mixed.

Most scientific studies that have examined the effects of seeding cumulus clouds on their health have found little or no evidence. However, wintertime seeding has produced positive results. Orographic clouds – clouds that form as air rises over a mountain – have Observed increases in precipitation.

Cloud seeding can be done in two ways. The first is to use dry ice or silver iodide to supercool clouds. This will cause ice crystals grow and consume moisture from the cloud, and then fall as snow or rain. It could be shot into the clouds by rockets, or sprayed from a mountaintop or airplane. The second involves warm clouds. HygroscopicMaterials like salt particles. These particles absorb water vapour and grow larger to fall quicker.

The amount of snow and rain that cloud seeding has caused has varied. Experiments in Australia revealed that up to 14% of the population was involved. Studies in the USA have found that precipitation has increased by just a few percentage points. Scientists found that precipitation has increased by a few percentage points in 2020. Used radar to monitor 20 minutes of cloud seedingThe moisture in clouds caused it to thicken and then fall. In just over an hours, about one-tenthof a millimeter worth of snow accumulated below the ground.

In 2015, another study used climate data and a Six-year cloud seeding experimentIt is possible to estimate this in the mountains of Wyoming Conditions were rightFor cloud seeding, it takes approximately a quarter of the time, from November to April. The snowpack would likely be increased by the results. Not more than 1.5%For the season.

Although encouraging, these experiments have not reached the level Schaefer and co-workers had hoped for.

Weather modification is back in fashion

Scientists are still carrying out random seeding experiments.To determine if cloud seeding increases precipitation and how much.

Some people have raised concerns about cloud seeding’s negative effects, but these effects are minor. Silver ion is an example of a Toxic heavy metalHowever, the amount silver iodide found in seeded snowpack must be detected using extremely sensitive instrumentation.

Weather modification is gaining popularity in response to extreme weather events and droughts.

The World Meteorological Organization reported that in 2017, weather modification programs including the suppression of crop-damaging hail and increasing rainfall and snowfall were in place. More than 50 countries. Colorado is my home state. Cloud-seeding operations supportedFor many years. Despite the mixed evidence, many communities still believe it will work.