Sunday, April 11, 2021

Snowflakes like you’ve never seen before


This winter snowflakes fell from the sky. It is of billions and trillions, now mostly melts as the spring approaches.

Some people watched them closely one by one.

Kenneth G. Liebrechreich, a professor of physics at the California Institute of Technology, has spent a quarter of a century trying to understand how such a simple substance – water – can freeze in a crowded shape.

“How do snowflakes form?” Dr. Libbrecht said An online chat on 23 February Was hosted by the Bruce Museum in Greenwich, Conn. “

Dr. Nathan P., one of those surrounded by Librecht’s snowflake research and photography. Was Mehrwold, a former Microsoft chief technology officer who has pursued projects in a myriad of scientific disciplines, including Paleontology, to Cook And Astro.

Dr. Mehrwold, a fond photographer, first appeared more than a decade before Drs. Libret had met, and in the spring of 2018, he decided he wanted to take pictures of intricate frozen crystals himself. He recalled thinking, “Oh, we’ll just throw some, and we’ll be ready for winter.”

But, as with many of his projects, things were not as simple as Drs. Mehrwold had a plan.

Dr. “It was massively more complicated than I thought,” Mehrwold said. “So it took 18 months to make a damn.”

The “damn thing” was the camera system for the snowflake being photographed. He wanted to use the best digital sensors that captured one million pixels. “The real snowflake is very fragile,” he said. “It’s super complicated. Therefore you want high resolution. “

But that type of sensor is usually much larger in area than images produced by microscope lenses, a result of decisions that microscope manufacturers made closer to a century ago.

This means that he needed to find a way to diffuse the microscope image to fill the sensor.

“I came up with a custom optical path that would actually allow it to work,” he said.

Then there is accommodation for optics. It is usually made of metal, but the metal expands when heated and shrinks when cooled. Dr. Mehrwold said “moving the equipment from inside the warm house to a fridge balcony where it would collect snowflakes” would tarnish the entire microscope.

Instead of metal, they used carbon fiber, which does not appreciate or expand.

Dr. Mehrwold also found a special LED, manufactured for industrial use by a company in Japan, that would emit 1 / 1,000th of a burst of light as a typical camera flash. This reduces the heat emitted by the flash, causing the ice pieces to melt slightly.

To view something under the microscope, a specimen is usually placed on a glass slide. But the glass retains heat. He also melts snowflakes. So they switched from glass to sapphire, a material that cools more easily.

By February 2020, he was ready. But where to find the most beautiful snowflakes for photos? At first, he thought he could settle in the ski resort city – maybe Aspen or Vail in Colorado or in British Columbia.

But these places were not very cold.

“The powder snow that a skier may like to ski through is, in fact, too much powder,” Dr. Myharold said. “There is not much beauty in those things.”

Actually, the snowflakes that fall on most people are rarely the ones that are ice-shaped.

Water is a simple molecule consisting of two hydrogen atoms and one oxygen. When the temperature drops below 32 degrees Fahrenheit, the molecules start clinging to each other – that is, they freeze.

A snowflake is born in a cloud when a small drop of water freezes into a small crystal of ice. The shape of the water molecules causes them to stack together in a hexagonal pattern. This is the reason why the arctic iceberg has six arms.

The crystal then grows, absorbs water vapor from the air and other nearby droplets evaporate to replenish the vapor. Dr. “It probably takes 100,000 water drops to form an ice crystal,” said Liebrechreich.

But how the crystal grows depends on the temperature and humidity. In the 1930s, a Japanese physicist, Ukichiro Nakaya, was the first to grow artificial snowflakes in his laboratory, and by varying the conditions, he was able to catalog those that make the type under most circumstances.

When the temperature is just below freezing, snowflakes are usually in simple hexagon plates. At about 20 degrees Fahrenheit, the prevailing shape is a hexagonal column. It is between 15 ° and -5 ° F which usually forms beautiful snowflakes.

At these temperatures, the points of the hexagon grow in the branches. The branches then span other branches and smaller hexagonal plates. A slight change in temperature and humidity affects the growing pattern, and the situation is constantly changing as the snowflake falls towards the ground.

“Because it is this complex path through the clouds, it gives a complex shape,” Dr. Liebrechurch said. “They are all following different paths, and so each one looks slightly different depending on the path.”

Thus, to find the beautiful snowflake, Drs. Mehrwold went north, far north. He and a few assistants gave nearly one thousand pounds of equipment to Fairbanks, Alaska; Yellowknife, the largest community in the Canadian Northwestern regions; And Timmins, Ontario, about 150 miles north of Lake Huron.

A month later, the coronavirus pandemic attempted on Hetus. But Dr. Mehrwold was able to carry what he calls images of the highest resolution of snowflakes ever.

That claim has troubled others in the snowflake world, including Don comerchka, A Canadian photographer who takes a decidedly less technical approach. He uses store-bought digital cameras with high-powered macro lenses. He doesn’t even use a tripod – he just holds the camera while the snowflakes sit on a black rat that his grandmother gave him.

“Incredibly simple,” Mr. Komareka said. “It’s so acceptable for anyone with any camera.”

He has given Dr. Said of Mehrwold’s custom-built system: “I think it’s a bit over-engineered.”

Mr. Komareka also adopts a different approach to illumination, using light reflected from a snowflake, while Drs. Mehrwold’s images pass through the light. “Komarechka said,” you get to see beautiful iridescent colors in the middle of the surface texture and sometimes snowflakes.

The rainbow effect is similar to what you see in a soap film, but the colors are “much more solidly displayed than you would see in a soap film or anything else.” “It’s almost a psychedelic color, almost resembling a tie-dye T-shirt.”

Dr. To counter Mehrwold’s claims, Mr. Komareka took an image, which he says was also of high resolution. Dr. Mehrwold replied A long rebuttal Explaining why his images were not, nevertheless, more elaborate.

In practical terms, Drs. Mehrwold’s images are sharp when printed on paper in expansive sizes. They are available for purchase Sizes ranging from 1.5 m to 2 m.

“In a very narrow sense, yes, this is what Nathan claims, and he is not wrong,” Mr. Komareka said.



Source link

Translate »