
Exodus Advanced Communications

Carl & Jerry: The Snow Machine
December 1960 Popular Electronics

December 1960 Popular Electronics

December 1960 Popular Electronics Cover - RF CafeTable of Contents


We are moving into the colder days of the year in the northern hemisphere. The normal high temperature here in Erie, Pennsylvania is around 49°F (35° today with snow on the ground for the last three days). It is the time of year that causes those less appreciative of cold weather to conjure up memories of warm summer days with green leaves on tree branches and colorful flowers in the garden. For those of you like me who actually prefer the cooler weather, this Carl & Jerry story about making snow by blasting clouds with ultrasonic energy just adds to my appreciation of the onset of winter and visions of a white Christmas. To date there has been no major, efficient progress in the field of snowmaking or rainmaking (other than seeding clouds with silver iodide). Ski resorts still need sub-freezing weather for their snow machines to work using a ground-based water source (not directly from the clouds).

Carl & Jerry: The Snow Machine

Carl & Jerry: The Snow Machine, December 1960 Popular Electronics - RF CafeBy John T. Frye W9EGV

Carl and Jerry were sitting in Mr. Gruber's study listening with deep interest to what their elderly neighbor and friend was saying.

"People today don't know what snow is," he snorted, his bright blue eyes flashing in his wrinkled face. "When I was a boy, the first snow usually fell around Thanksgiving; and many times we never saw bare ground again all winter. The snow was deep, too; and they needn't try and tell me it only seemed so because I was measuring it against my shorter boyish legs."

The boys waited expectantly to see what would follow Mr. Gruber's reference to his boyhood. They knew that with Mr. Gruber the past was simply a storehouse where he went to get an experience or a memory that could be of current use. He did not live there, as many old people do. He lived in the present and in the future. He knew far more about missiles and satellites than either Carl or Jerry, and he had a keen, daring mind.

"I've read that this part of the world has been experiencing a warming trend for the last several years," Jerry offered.

"It's high time they admitted it," Mr. Gruber said, getting to his feet. He put on his battered derby hat and tapped it into place with a firm slap on the crown. "You boys come on out to the shop. I've got something to show you."

The boys put on their coats and followed the old gentleman out the back door into the rapidly fading winter day. There was a damp chill in the air and a low bank of clouds in the southwest.

"A couple of nights ago my nephew - that's my wife's sister's boy - dropped in to see us," Mr. Gruber explained. "He's a salesman for a West Coast electronics outfit, and he had a demonstration unit with him that I know will interest you two. He tows it behind his car in that trailer sitting beside the garage; but we rolled the gadget out and into the shop."

Extremely heavy-duty speaker - RF CafeAs they stepped into the small, neat workshop, Carl and Jerry saw a bulky piece of electronic gear standing on heavy rollers in the middle of the floor. Several panels were arranged in a special shielded rack, and they carried a dazzling array of meters, knobs, vari-colored pilot lamps, and push-buttons. One heavy cable ran from the cabinet to the 220-volt outlet box on the wall. Another ran to what looked like an extremely heavy-duty speaker mounted in a gimbal-like arrangement that permitted it to be pointed in any direction by proper adjustment of a pair of hand-wheels. This apparatus rested on its own set of rollers. When the boys examined it closely, they saw that the cone of the "speaker" was made of heavy steel that looked like boiler plate.

"What on earth is it?" Carl asked in awe. "It's a super-duper, high-power ultrasonic amplifier," Mr. Gruber explained, patting the rack-and-panel fondly. "If I've got my figures straight, it costs around $80,000; it uses tubes with 7000 volts on the plates drawing 3 amperes of current; and it puts 350 volts at 30 amperes on the voice coil of the transducer there."

"Whe-e-e-ew!" Jerry whistled softly, "ten and a half kilowatts of audio power! What's it do besides split eardrums?"

"For one thing, manufacturers use it to check the effect of ultrasonic vibrations, such as those produced by air-buffeting at extreme speeds, on products designed to be mounted in missiles. You boys weren't around when my nephew had it going. He was called home to California suddenly because his father suffered a heart attack, but he taught me how to run it and said I could show it to you."

As he finished speaking, Mr. Gruber up-ended an empty cardboard carton on top of a block of wood with the open side of the box facing the transducer. A large Coca Cola bottle was placed well back in the carton, and the block of wood was slid to within about three feet of the cone. Then the transducer was aimed directly at the center of the bottle.

"Put these in your ears," Mr. Gruber directed as he handed the boys some rubber ear plugs. "The frequency is too high to be heard as sound, but we don't want to take any chance on injuring our ear drums."

A few moments later Mr. Gruber said, "I guess we're ready, then," a little nervously. He reached over and gingerly pushed a button on the panel of the instrument. A green pilot lamp came on, and a low hum issued from deep inside the rack. After about a minute an orange lamp began to glow.

"Stand back!" Mr. Gruber shouted to the boys as he crouched down beside the rack and pushed another button. A red pilot lamp flashed on, and the hum increased. Very slowly Mr. Gruber began to turn a control on the top panel clockwise; he had hardly advanced it a fourth of a revolution when there was a brittle snapping sound, and the bottle flew to pieces.

"Literally shook to pieces by ultrasonic waves!" Mr. Gruber exclaimed happily as he examined the little pieces of glass scattered over the bottom of the carton. "But let's go back to the house. I want your opinion about something, and it's too cold out here for my tired blood."

"What I'm going to suggest may sound pretty silly to you," Mr. Gruber warned as they settled down in the study and he took a little red notebook from his pocket; "but it's gotta come out; so here goes:

"For a long time now I've been interested in snow, especially in how it's produced naturally and in the experiments to produce it artificially. Snow is a solid form of water which grows while floating, rising, or falling in the free air of the atmosphere. It begins ordinarily in a cloud of moist air that's super-cooled below the freezing temperature of water, but the particles of moisture don't crystallize into snow until they find a nucleus around which they can cluster. Once a crystal is started, it moves up and down through the cloud, gathering more and more ice, until finally it's heavy enough to fall to earth as a snowflake; or, if the lower atmosphere is warm enough to melt it, as a rain drop. Yes, even on the hottest August afternoon, a rain shower was once a snow shower in the upper atmosphere.

He threw on the power - RF Cafe"Back in 1946 Vincent Schaefer of the General Electric Research Laboratories transformed a super-cooled, four-mile-long, alto-stratus cloud into snow by 'seeding' it with only six pounds of solid carbon dioxide. Later B. Vonnegut, a co-worker of Schaefer's, found that silver iodide was particularly effective as a seeding nucleus because its structure matched the structure of ice to within 1%. But there is apparently another way ice crystals can be formed - by the sudden rarefaction of cold, moist air, such as is produced by detonation, adiabatic expansion, high-velocity missiles, or vortices which cool the air abruptly below the water transition temperature of -38° F. It's believed that this is what causes vapor trails behind high-flying planes.

"Now you boys know," Mr. Gruber continued slowly, "that a sound wave creates alternate areas of compression and rarefaction in the atmosphere. I've long wondered if powerful sound waves directed into a proper cloud might not produce ice crystals that could grow into snowflakes. I never hoped to have the apparatus to carry out such an experiment; but suddenly it's sitting right out there in my shop. Maybe you boys would like to help me try the experiment after supper. I've been watching the weather closely, and conditions should be about right."

"Would we ever!" Carl exclaimed.

"We'll be here," Jerry promised as he reached for his jacket; "but the forecast calls for cold and cloudy weather with no precipitation; so if we have any snow, I guess you'll have to make it."

It was around eight o'clock when the three of them gathered in Mr. Gruber's shop. A lighted gas trash-burner in the corner took the chill off the interior, but it was bone-chilling cold and damp outside. Carefully they wheeled the amplifier and the transducer out on the concrete apron behind the shop and pointed the cone straight up.

The apparatus was turned on, and as it warmed up Mr. Gruber carefully noted the temperature, humidity, and atmospheric pressure in his little red notebook. Then he threw on the power and firmly advanced the power output control as far as it would go. As the boys watched, their ear plugs in place, he used the hand-wheels to sweep the amplifier's ultrasonic beam carefully back and forth.

This went on for several minutes. Suddenly something that felt like a light cobweb brushed Jerry's cheek. At the same time Mr. Gruber snatched off his derby hat and dashed into the lighted shop with it.

"Diamond dust!" he shouted triumphantly as he pointed to gleaming specks sprinkled over the crown of the derby. "That's what they call these tiny ice crystals that form close to the ground, usually in very cold weather. Now if they will just move up and down through the clouds, we may have some real snowflakes soon. Back to the snow machine, men!"

The little diamond dust particles must have danced up and down in the clouds just as Mr. Gruber hoped they would, for soon honest-to-goodness snowflakes began to fall. They were small and scattered at first, but they rapidly increased in size and frequency; it became necessary to shut off the amplifier and wheel it into the shop.

The boys watched, their ear plugs in place - RF CafeThe old man stood in the open doorway watching anxiously to see if the snow would stop, but instead the flakes grew larger and thicker.

When the boys finally went home, there was already a couple of inches of snow on the ground, and it was snowing harder than ever; but the ten-o'clock TV weatherman said it was just a freak snow shower and would soon end.

The weatherman was wrong, though, very wrong. When Jerry was awakened next morning by the sound of snow shovels scraping on the sidewalk, it was snowing so hard he could scarcely see across the street; and there was a good foot of snow on the ground. As soon as breakfast was over, he grabbed his snow shovel and headed for Mr. Gruber's house. Carl was already busy cleaning off the old man's walk; and the latter, a scarf tied over the top of his derby and beneath his chin, was literally dancing in his own personal snowstorm.

"Now these whippersnappers can see what an old-fashioned snow really looks like!" he gloated.

It never let up a minute the whole day. By evening, traffic in the city was at a complete standstill. The mayor went on the local radio station and asked everyone to remain calm in the emergency. Citizens were requested to stay in their homes and to be exceptionally careful of fire, since fire trucks could not get through the snow-clogged streets.

All of the weather forecasters were frankly astonished at the storm. They said it was a freak affair that could happen only once in a thousand times. Warm, moist air coming up from the Gulf had been suddenly lifted by a narrow wedge of polar air that had knifed down from Canada; and the front that resulted had stalled directly over the city. With two feet of snow in town, bare earth could be seen not fifty miles away.

Mr. Gruber telephoned right after the news broadcast and asked both boys to come to his shop. They floundered through the high snow banks, and as they stepped through the door they saw Mr. Gruber toss the little red notebook with all his records of the snow-making experiment into the trash burner. He looked sick.

Snowflakes began to fall - RF Cafe"This is a terrible, terrible thing, boys, and it's all my fault," he groaned. "This is what happens when you rashly undertake an experiment without considering all the possibilities. I want you two to promise me you will never tell anyone what we discovered last night. Power to make it snow is too dangerous to rest in human hands."

The boys promised and did their best to cheer him up, but it was no use. He turned off the lights and trudged wearily through the snow to his back door.

"Wait, Mr. Gruber!" Carl suddenly called, as he lifted a startled face to the sky. "It's stopped snowing!"

"Thank heaven!" the old man exclaimed.

He straightened up and saw it was true. "Now I can sleep. Good night, boys."

Carl and Jerry stood outside between their houses for a few minutes and watched the stars peep out one by one. Finally the moon slid from behind a cloud and bathed the snowy landscape in a beautiful white light.

"Jer," Carl finally asked as he stared up at the sky, "do you really think that the machine caused all this snow?"

"We'll probably never know," Jerry said slowly; "but no one will ever convince Mr. Gruber that it didn't. As for me, whether the machine worked or not, it has taught me a lesson I'll never forget: power carries with it a terrible responsibility. Good night, Carl."

Carl & Jerry Episodes on RF Cafe


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Posted November 14, 2018

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