salt resonance experiment

Metal plate resonance experiments using only household items

So instead of fancy equipment, I'm using a tablet computer, some computer speakers, a cookie sheet, and some salt.

Next I used an app called "Frequency generator" on the tablet to make that frequency of sound.

The salt in areas of strong vibration tends to bounce away from those areas and settle where vibrations are weaker. So the lines formed by the salt show the "nodes" of the vibration — areas between the stronger vibrations.

So I tore it open to see the damage. The voice coil was blackened (it's normally red magnet wire). The heat had caused it to distort, and then it rubbed against the magnet.

I also switched from salt to sand so it would show up better against the white surface.

I wasn't able to get results as clean or spectacular as other experiments on YouTube, but the cool thing is, I was able to do these experiments without using any scientific equipment - using just regular household items!

How to Make a Chladni Plate (vibrating Membrane)

Introduction: How to Make a Chladni Plate (vibrating Membrane)

• work with cheap off the shelf components
• use as much of my own kit as possible (my conventional audio amplifier etc.)
• avoid destroying the speaker
• use a plastic membrane that is cheaper and requires less power (less noise for my neighbours)

• It provides a great acoustic contact that bonds to plastic sheet, board, metal, glass
• creates a perfect seal between the speaker and the plate
• you have time to make the whole set-up level before the sugru cures
• can also create custom-made dampening pads for the contact with the table the rig sits on.
• I don't need to destroy my nice speaker since I can cut sugru and re-use my speaker once the experiment is done

Step 1: Build the Base

• Computer _ £ 0 (we assume you already have one)
• Sound amp _ £ 0 (we assume you already have one)
• Speaker (here I use a 10W car speaker) _ £10 at Maplins  (UK) / Radioshack (USA) If you want to use a more expensive speaker you already own, you can! Especially because it is easy to cut and remove sugru . 
• Paint bucket _ £2.5 at the local DIY paint shop
• Plastic membrane _ £3 
• Set of 4 x M5 (5mm) nuts and bolts _ £ 2.5
• Duct tape _ £2
• Rubber ring _ 0.10
• sugru 3x5 gr _£ 6.5
• Scrap wood board
• _TOTAL BUDGET  = £26.6 ( $ 41.25)
• Cordless drill + drill bit ø5mm
• Ruler / 90 angle
• Spirit level
• 1.5 hours to build with 2 people
• 6 hours for sugru to cure (overnight)
• 3 hours to play with tones

Step 2: Amplifying Cone

• So the idea is to roll some sugru in long rolls. 
• Install the long sugru rolls on the most outer ring of the speaker. 
• Make sure that the sugru is not interfering with any moving parts. 
• Flip the bucket upside down, opening facing downwards. 
• Install the speaker on top of the bucket bottom.
• Adjust the level roughly with 2 mini-spirit levels if you have them
• Prepare 4 or more contact points between the speaker and the platform. 
• Assemble the platform on top of the amplifying cone and speaker. 

Step 3: Install the Membrane

• Position the plastic sheet with A LOT of slack
• Hold the sheet in position with a rubber ring
• Create a "belt" of adhesive around the bucket, cut the slack
• just like when you adjust a traditional percussion, you want to adjust the tension on one side, and immediately adjust on the opposite side. 
• Eventually you can gently tap on the surface and find out if the tension is correctly distributed. The idea is that it would sound like a high pitch percussion drum. In fact, you could use an adjustable drum membrane to do this even more accurately, here an awesome video of how to adjust a darbuka head skin here (watch the end, spectacular!).   

Step 4: Assemble and Adjust

• it is level
• your neighbours do not mind low and high pitch loud sound to be played.  
• I recommend you use earplugs. Do not use noise cancelling headphones . 

Step 5: Software

Step 6: Play! /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

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Sound is a vibration, a demonstration

A small styrofoam (or pith) ball on a thread is held next to a vibrating 512-C tuning fork . You can’t see the tuning fork’s movement, but the styrofoam ball responds. This is a demonstration to prove that a vibrating body can capable of producing sound , a Science Sir video.

In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the reception of such waves and their perception by the brain. Only acoustic waves that have frequencies lying between about 20 Hz and 20 kHz elicit an auditory percept in humans. Sound waves above 20 kHz are known as ultrasound and are not audible to humans. Sound waves below 20 Hz are known as infrasound . Different animal species have varying hearing ranges.

Here’s another version of the first experiment: Tuning Forks Resonance + Ping Pong Ball , this time with two tuning forks that have matching frequencies. As the first tuning fork is struck, sympathetic resonance sets the second tuning fork and its neighboring ping pong ball(?) in motion.

Read more about tuning forks at How Stuff Works. Then watch this: Resonance, forced vibration, and a tuning forks demo .

Related DIY: This salt experiment with sound and vibration and this “secret bell” experiment from Scientific American .

Bonus: Watch Chladni Plate Sand Vibration Patterns and more videos about resonance , frequency , vibration , and sound .

This Webby award-winning video collection exists to help teachers, librarians, and families spark kid wonder and curiosity. TKSST features smarter, more meaningful content than what's usually served up by YouTube's algorithms, and amplifies the creators who make that content.

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What does a tibetan singing bowl sound like, the science of hearing, the great stalacpipe organ deep in luray caverns.

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Dancing Salt

Discover how music creates vibrations you can see using salt and a portable speaker! Then try experimenting with different genres of music to see which ones make the salt dance more.

What's going on?

Speakers, like your Bluetooth speaker, produce sound by creating vibrations in the air. Normally, we only hear these vibrations, and we can't easily see them. Plastic wrap, though, is lightweight and thin enough to vibrate in response to the sounds coming from the speakers. These vibrations move through the plastic wrap unevenly, pushing and shoving the salt around in interesting patterns. As a song progresses, these vibrations change, and the salt moves as if it were dancing.

If you can find a YouTube video of a pure tone (like a single, sustained note), observe what happens to the salt when you play that tone through the speakers. A pure tone will create a consistent, unchanging vibration in the plastic wrap. Instead of dancing around, the salt should collect in places in the plastic wrap that aren't vibrating, making patterns that depend on the frequency of the pure tone. Try a few other pure tones, one at a time, to see some other interesting patterns!

Ages: 9 - 16

30 minutes - 1 hour

Materials you'll need

• speaker (bluetooth)
• popsicle stick (6)
• plastic wrap
• rubber band
• food coloring (optional)

Step-by-step tutorial

With the speaker facing up, tape six popsicle sticks around the outside of the speaker.

Cut a piece of plastic wrap large enough to cover and stretch tightly over the top of the popsicle sticks and secure with a rubber band.

Final result!

Sprinkle salt onto the plastic wrap. Then, connect the speaker to the cell phone, play a song, and watch the salt move to the music! Troubleshooting : If the salt isn’t moving, first try increasing the volume. If it still isn’t moving, try moving the plastic wrap closer to the speaker by shortening the distance between the top of the popsicle sticks and the speaker. Optional : To see the salt more clearly, try dyeing it with food coloring! Simply combine salt and one or two drops of food coloring in a sandwich bag and shake the bag until fully mixed.

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Amazing resonance experiment video shows frequency as the secret to complexity.

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Nikola Tesla famously said , “If you want to find the secrets of the universe, think in terms of energy, frequency and vibration.” The video above by the pseudonymous Belgian optical illusionist  Brusspup (previously featured on Forbes.com here ) has made the best documentation so far of the Chladni plate experiment, where grains of salt are vibrated on a square plate. At certain predictable audio frequencies, the randomly sprinkled sand organizes itself into predictable graphic patterns.

A low tech version of the experiment is shown in this UCLA lecture demonstration , where a bass fiddle bow is used to generate the frequencies. Brusspup used a signal generator that he was able to tune to specific frequencies. The video above is edited and he has added an instrumental soundtrack. It is shorter with less objectionable sound than the raw version (see below), but I prefer to actually hear the tones change as they generate the patterns on the plate.

WARNING: This version plays the ACTUAL TONES used to generate the resonance designs and the sound can get VERY LOUD! It is advised to TURN YOUR SPEAKERS DOWN when watching this video!

The pleasure of watching this experiment is that it is pure physics in action. One of the wonders of the natural world is how chaos coalesces into ordered patterns. On the human plane, especially for entrepreneurs and developers, the lesson here is that you have to understand where the viable niches are—where you idea can stabilize at a sustainable frequency—and tune your product into them. The video below not only shows another way to make sound frequency visible, but also how being just off the beat can create an illusion of movement.

Bonus Round: See what Brusspup can do with a 24Hz sine wave and a garden hose!

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Science Fun

Salt Crystals Science Experiment

In this fun and easy crystal science experiment, we’re going to grow salt crystals.  

Note: Since hot water in involved, please insure adult supervision is utilized.

• Piece of string

Instructions:

• Fill the jar with hot water.
• Slowly stir in several tablespoons of salt.
• Tie one end of the string around the nail.
• Next tie the other end of the string around the pencil in a way that the nail will be suspended just above the bottom of the jar when the pencil is laid across the mouth of the jar.
• The water will dry up after several days and your string will be covered with salt crystals.

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How it Works:

The salt dissolves in the heated water. As the water cools, it becomes less able to hold the salt. The salt then clings to the string and forms crystals. 

Make This A Science Project:

Experiment with different types of solutions and observe and record any differences in the rate of crystals creation. Some ideas may be Epsom salts, Borax, or sugar (do not eat). 

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Science Friday

Seeing the patterns in sound.

A pair of artists finds ghostly imagery in sound vibrations.

Vibrations of D. Credit: Louviere + Vanessa

In the late 18 th century, German physicist and musician Ernst Chladni demonstrated how vibrations could be used to create striking imagery. By spreading fine sand across the top of a metal plate and running a violin bow alongside, Chladni showed that the sand would settle into distinct patterns, depending on the frequencies of the sound waves produced by the bow.

Centuries later, in the 1960s, a Swiss physician named Hans Jenny built on Chladni’s experiments in an effort to study vibrational phenomena—what he called “ cymatics .” Visual artist Jeff Louviere happened upon the works of Jenny and Chladni while researching another project, and he and his partner, photographer Vanessa Brown, became inspired to conduct their own experiments to see what sound could look like. The resulting work became Resonantia (Latin for “echo”), a multimedia project centered around 12 images produced by vibrations.

To create the images, the pair (also known as Louviere + Vanessa ) built their own version of a Chladni plate in their New Orleans home. Louviere dismantled one of his guitar amps and separated the speaker, aiming it upwards. On top of the speaker, he placed a lined box and filled it with water and black food coloring. He then hooked the speaker up to an amp plugged into a frequency generator—that is, a computer program with an oscillator—that he could use to play musical notes at various frequencies. A bright ring light mounted over the box illuminated the water below.

As Louviere cycled through musical notes at different frequencies and volumes, from low to ear-piercing—“there was a point where it was so high we had to put the dogs outside so it wouldn’t hurt their ears,” he says—Brown took photographs through the ring light of the water formations produced by the vibrations.

“It was just constant shooting, and trying like every frequency we could stand,” Louviere says.

Brown took about 2,000 photographs in total, and the duo narrowed those down to a dozen, based on the 12 notes of the chromatic scale. They chose the images with the most complex or aesthetically pleasing patterns.

Louviere says he was surprised by some of the patterns they produced. “It’s the first time we’ve done a series of work where we didn’t know what the end result was going to look like,” he says. One of his favorites is the image for F sharp, which is “kind of a weird sound,” he says. The result looked “ like a puffer fish or an alien or something ; it’s got all these crazy lines in it. That one was pretty remarkable.”

And the image for G turned out to be even more eerie. Louviere had been researching the frequencies of various sounds like heartbeats and hurricanes when he read a conspiracy theory about a strange hum called the brown note —a low frequency that would supposedly cause people to lose control of their bowels. When Louviere tried to hit that frequency with their device, Brown captured a vibration pattern that looked like a demonic face.

“It looked like Satan,” Louviere says. “We were like, oh my god.”

Satanic visages aside, the images themselves are a creative example of physics at work. “It’s kind of a classic demonstration in acoustics,” says Trevor Cox, a professor of acoustic engineering at the University of Salford in England. “These are actual physical patterns.”

Every object has a characteristic frequency, or frequencies, at which it vibrates most, with the least input of energy. Those vibrations are associated with standing wave patterns called modes . When the Chladni plate, for instance, vibrates in one of its modes, a pattern appears in the sand on the plate.

“What’s happening is, the sand is moving away from the bits [on the plate] where it’s vibrating a lot” says Cox, and it’s settling in places where there are no vibrations (these places are called “nodes”). And, “if you up the frequency, you’ll find the patterns get really complicated,” because more of those nodes occur.

Cox, who isn’t affiliated with Resonantia , surmises that the patterns depicted in the images formed when the water vibrated in its natural mode. The bright light that Brown shone on the water illuminated the areas that rippled the most.

To achieve the vintage look of the final images, Louviere + Vanessa first printed each photograph onto kozo paper, which is thin and tissue-like, and lay that on top of a metal substrate covered in gold leaf. Then they poured resin over the paper, which turned transparent, allowing the gold leaf to shine through.

The prints have been on display at various galleries across the United States, including A Gallery for Fine Photography in New Orleans and the Verve Gallery in Santa Fe, New Mexico. You can also learn more about a record and music video that Louviere + Vanessa produced for Resonantia , based on the sounds and images, here .

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20 Surprising Science Experiments with Salt (Kids Will Love Them)

• October 23, 2020
• Science Experiments

Our houses have many ingredients that serves as a key component for performing a lot many simple science experiments.

I am sure, you would never imagine how useful SALT can be around your home to engage your kids with fun learning and to explore the world of science around you and your kids.

Science Experiments with Salt

All the experiments are super fun, simple, easy to do, no messy, easy to set up, and especially unique science activities. Here we go!

1. Salt Painting Science Experiment

If you are looking for a simple science and art project , then this awesome salt painting science experiment is a great way to explore about simple concepts of science such as absorption. Pre-schoolers and home schoolers find this experiment a great way to learn science concepts.

Find more details of this amazing science experiment here: Salt Painting Science Experiment

2. Desalinization Science Experiment

The word ‘Desalinisation’ is an intimidating word for young children. But believe me, with this spectacular science experiment kids easily learn marine biology hands-on.

Supplies and instructions for desalinisation are found here: Desalinisation Science Experiment

3. Floating Egg Science Experiment

What happens to an egg placed in the salt water? Did you know that an egg can be floated in the water? Simple salt water experiment to teach kids about density and fresh water in a fun and entertaining way. Awesome kitchen science experiment for children of grades 1-5.

Are you interested in learning the complete instructions of the experiment? Click on Floating Egg Science Experiment

4. Make Ice-Cream in a Bag Science Activity

Kids will love to make their own ice creams and end up with a great tasting desert while learning a lot of chemistry science . This is such an awesome kitchen science experiment that finishes in 10 minutes . How cool is it!!

Engage your kids in making ice cream with complete instructions. Find details here: Make Ice-Cream in a Bag Science Activity

5. Melting Ice Salt Science Experiment

Children will learn how salt melts ice with this super cool science activity. It seems simple and easy but encourage kids to explore a lot of science.

Do not miss to check out Melting Ice Salt Science Experiment for more information in detail.  

6. Grow Salt Crystals Science Activity

Growing salt crystals is a simple science experiment that is popular to make kids learn about chemical reactions involved to form crystals. Fun and engaging Easter Science Activity! Kids will have a ton of fun while learning how to grow salt crystals at the same time.

Get more details of the experiment here: Grow Salt Crystals Science Activity

7 . Ice and Salt Science Experiment

Here is an awesome science activity fills the days of the children in grades 1-7 with some simple science concepts. It’s a fun STEAM (science, technology, engineering, art, Math) activity for kids.

Check out here, Ice and Salt Science Experiment

8. Sticky Ice Science Experiment

This kid’s friendly science experiment with ice is simply too cool, quick, easy, and little magical. Kids will get to learn about freezing point of water and its effects on salt in a fun way. Challenge your children to lift the ice cube just using a thread!  

Click here Sticky Ice Science Experiment to learn full description of this super classic science experiment.

9. Egg Geodes Science Experiment

Fun and successful science fair project with egg geodes make the children sharp in developing their critical thinking and questioning skills leaving a wow factor on their faces.

Want to give it a try!? Click on Egg Geodes Science Experiment .

10. Homemade Slushy Drink with Ice and Salt Experiment

Let your kids learn about freezing and melting points while having fun in making homemade slushy drink on their own. This simple science activity offers a great alternate method of making ice cream and cooling drinks very quickly. Sounds entertaining!!

Get the complete description about this classic science experiment here: Homemade Slushy Drink with Ice and Salt Experiment

11. Salt Vibrations STEAM Activity

Here on it is not intimidating to understand the concept of sounds. Easy and fun science STEAM activity that teaches kids about sounds caused by vibrations. In fact, kids are allowed to enjoy this demonstration that actually shows kids the sound waves in action. Click on Salt Vibrations STEAM Activity

12. Salt Water Experiment Ocean Science

A terrific salt science experiment for pre-schoolers! An awesome kitchen science experiment to teach kids about density of salt water versus fresh water. This experiment offers great time to learn about the difference between fresh river water and salty ocean water. What a cool activity!

Click on Salt Water Experiment Ocean Science to find more details

13. Growing Gummy Bears Science Experiment

Have you ever wondered of watching growing gummy bears? Do you think it is hard to witness? Absolutely not! Do this simple science experiment to show how this common kitchen hold mineral effects gummy bears?

Check out here to find simple step-by-step information and instructions: Growing Gummy Bears Science Experiment

1 4 . Rainbow Salt Circuit Science Experiment

Creating an electric circuit using common kitchen hold mineral i.e. salt is an amazing experience for the kids. A great hands-on examination on circuits making kids scientific knowledge on power and circuits little more interesting and exciting.

Are you interested in creating your own salt circuit with water? Then click on Rainbow Salt Circuit Science Experiment

15. Cleaning Pennies Science Experiment

All the kids love to play with pennies and while playing they even observed at times some pennies look dull and some other look bright. Just remind your children about this and ask them to guess what the reason behind that is. Let them explain their versions and then explain them about this cool science experiment. They love to do this hands-on activity to watch the magical results of cleaning pennies. Just browse Cleaning Pennies Science Experiment

16. Salt Pendulum Science Experiment

Salt pendulum is a fun art and science fair project for kids of all ages. Let your kids explore the science behind changing times and pendulums hands-on. While investigating the experiment ask your child to predict the time according to the movements of pendulums and predict what impacts time change. Also help them to understand the concept by explaining how salt effects this experiment in a fun way.

Find more details of the experiment here: Salt Pendulum Science Experiment

17. Popcorn and Salt Science Experiment

Let your kiddos think about their own scientific thought process with this easy and simple science activity to do with salt and popcorns. Using just three ingredients you can bring a lot of change in your child’s scientific knowledge. Easy to set up experiment with great results, highlights the difference between mass and volume using kid’s most favourite snack.

Are you ready to experiment with popcorns and salt : Popcorn and Salt Science Experiment

18. Lava Lamp Cool Science Experiment

An excellent way to explore density of liquids using simple ingredients you have right in your kitchen. Fun way to explore density of liquids and great opportunity to practice mixing colors. Besides, this is an easy going science and sensory play experiment as it makes children much more excited and attentive to study the simple science concepts using salt.

Click on Lava Lamp Cool Science Experiment for more information.

19. Static Electricity Balloon and Salt and Pepper Experiment

Children might have observed a balloon sticking to something like hair strands, comb, salt, etc.  Throw a question to your children on the magical science involved in this process of sticking to things. Static Electricity Balloon and Salt and Pepper experiment is all about explaining static electricity in a fun way. Isn’t it excited? Best and simple science experiment for your elementary children : Static Electricity Balloon and Salt and Pepper Experiment

20. Solid-Solid Separation science Experiment

An amazing easy fun science activity that teaches kids to understand about three science concepts i.e. evaporation, sedimentation, and filtration. How amazing is it to explain the three main science concepts while performing a single science investigation.

Click on Solid-Solid Separation science Experiment

So, here are the simple and easy science experiments to do with common kitchen hold mineral, salt. There is a lot of science involved in these super cool experiments that will surely amaze you and your kids. Simple science experiments that everyone will love! Fun and fascinating experiments for toddlers , pre-schoolers, and even some are perfect for older kids. Have a look and enjoy experimenting with salt. Happy Experimenting!!

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Put Salt On A Speaker And Something Really Cool Happens

This video by YouTube user and musician Brasspup shows us one of life's little moments where science and art can become one and the same.

The Chladni experiment itself is nothing new. It's a technique that shows how sound waves affect physical matter and the air around us.

It also has an extremely cool side effect which is that if you place small granules like salt or sugar on a base plate attached to a speaker then once a sound is played the granules create a stunning array of patterns.

The patterns are actually showing the nodal lines, areas on the plate where the metal isn't resonating allowing the granules to sit still.

The technique is still used in the construction of musical instruments however it serves the double purpose of entertaining people like us.

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Geometricon

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Fascinating Resonance Experiment

July 28, 2014 by Poly Hedra

Salt and sound form mesmerising geometric shapes on a metal plate. Amazing power of frequency!

Could spraying sea salt into the clouds cool the planet?

An experiment in Alameda, Calif. highlights the controversy surrounding research on altering the environment to cool the planet.

A city council meeting in Alameda, Calif. on Tuesday will take center stage in the global controversy over whether to try cool the planet by making clouds brighter.

Researchers at the University of Washington are studying a concept called “ marine cloud brightening ,” which aims to slow climate change by spraying clouds with sea salt. Salt particles help clouds form tiny, shiny water droplets, which reflect sunlight away from the earth before it can heat the planet.

In April, University of Washington scientists started testing a saltwater spraying machine on the deck of the USS Hornet, a retired aircraft carrier docked in Alameda. The city paused the experiment in May, citing health and environmental concerns — but outside consultants hired by the city later concluded the test doesn’t pose “a measurable health risk to the surrounding community.”

The Alameda experiment isn’t meant to “alter clouds or any aspect of the local weather or climate,” according to Sarah Doherty, a University of Washington atmospheric scientist who runs the university’s marine cloud brightening program. The scientists are only testing whether their salt spray machine works and studying how salt particles move through the air.

“Frankly, it was about as innocuous an experiment as one can do,” said Gernot Wagner, a climate economist at Columbia Business School who wrote a book on planet-cooling technologies, “ Geoengineering: the Gamble ,” and is not involved in the study.

The episode highlights the stiff opposition scientists face when they research anything related to geoengineering, a broad category of techniques that aim to manipulate the climate. Some environmentalists argue that these ideas could have dangerous, unpredictable side effects — and are a distraction from cutting carbon emissions, the most surefire way to avoid climate change.

“Geoengineering experiments, like the Marine Cloud Brightening project in the Bay Area, set a dangerous precedent and risk legitimizing a highly-speculative and harmful technology,” wrote Mary Church, who heads geoengineering advocacy for the Center for International Environmental Law (CIEL), an American and Swiss environmental nonprofit.

Environmental groups including the CIEL are calling on Alameda officials to end the University of Washington experiment . City council members will decide Tuesday whether the researchers can continue their study, which they hope to run for several more months.

What is marine cloud brightening?

Marine cloud brightening attempts to cool the planet by reflecting more sunlight back into space. Some scientists hope it could buy humanity more time to cut carbon emissions — or protect overheated ocean environments such as the Great Barrier Reef.

The fluffy, white tops of certain clouds act like a natural sunscreen for the planet; the water droplets and ice crystals within reflect 30 to 60 percent of sunlight that hits them, according to NASA. Geoengineering researchers believe they can make clouds brighter — and increase their cooling effect — by increasing the number of droplets they contain.

Since 1990, researchers have theorized they could do this by spraying clouds with sea salt particles , which give the moisture in the air something to glom onto so they can form water droplets, or ice crystals. This already happens naturally when ocean winds blow sea foam high into the air, but scientists believe they can amp up the process to noticeably lower the temperature underneath a cloud.

But scientists don’t have machines that can reliably spray sea salt particles at the right size and in the right quantity to alter clouds, making it hard to try this in the real world. The experiment in Alameda is meant to test a new salt spray machine to see if it works outside of a lab — and to study some basic physics about how particles move through the air.

Doherty stressed that the University of Washington researchers are not trying to brighten clouds in Alameda, but added that the experiment will help “study how clouds respond to particles … in the atmosphere and how this influences climate, including both the effects of pollution aerosols and the potential for brightening marine clouds to reduce climate warming.”

The shipping industry ran what amounted to an accidental test of the idea for decades, by emitting tons of sulfur dioxide into the atmosphere from ships’ smokestacks. The sulfur particles, like salt, helped form water droplets in clouds. When new rules forced the ships to stop emitting sulfur in 2020, ocean temperatures rose — largely because ocean clouds were no longer as bright , according to a study published last month in Communications Earth & Environment.

Australian researchers at Southern Cross University began a small experiment with marine cloud brightening near the Great Barrier Reef in 2020 but haven’t published conclusive results.

Why is marine cloud brightening controversial?

Some environmental groups oppose marine cloud brightening and other geoengineering techniques because they worry altering planetary systems will have unintended consequences and give polluters an excuse to keep pumping carbon into the atmosphere.

More than 70 environmental nonprofits and activist groups wrote an open letter opposing this line of research last month. “Geoengineering our oceans is a dangerous distraction from the real solutions to the climate crisis and gives the fossil fuel industry a potential escape hatch while putting our oceans and coastal communities at serious risk,” they wrote.

Earlier this year, Harvard scientists gave up a decade-long quest to test a different geoengineering tactic that would involve releasing particles from a hot-air balloon high into the stratosphere to reflect sunlight. The researchers tried and failed to get approval to launch the balloon from Arizona, New Mexico and finally Sweden, whose government canceled the experiment under pressure from the Saami Council , which represents Indigenous groups in Finland, Russia, Norway and Sweden.

“There’s a fair number of people who think there shouldn’t be research [on geoengineering], and these early experiments have become a proxy battleground for this larger question about how to think about the development of these technologies,” said David Keith, who now directs the Climate Systems Engineering Initiative at the University of Chicago and used to be involved in the Harvard geoengineering experiment.

Local fights over small experiments like the one in Alameda are likely to define the future of geoengineering research in the coming years, Keith said.

“This generation is not likely to be the one that makes decisions about actually deploying these technologies,” he said. “Those will only get made in 20 years by the next generation. Right now, our only real choice is: Do we research them or do we not?”