High-Speed Camera Grabs First 3D Shots of Untouched Snowflakes

sciencehabit writes "Researchers have developed a camera system that shoots untouched flakes 'in the wild' as they fall from the sky. By grabbing a series of images of the tumbling crystals—its exposure time is one-40,000th of a second, compared with about one-200th in normal photography—the camera is revealing the true shape diversity of snowflakes. Besides providing beautiful real-time 3D snowflake photographs from a ski resort in Utah, the goal is to improve weather modeling. More accurate data on how fast snowflakes fall and how their shapes interacts with radar will improve predictions of when and where storms will dump snow and how much."

Comments

why are snowflakes symmetric?

[The_Rook]

what i've always wanted to know was why are snowflakes symmetric?

sure, a hexagonal crystal has bilateral symmetry etc. but snowflakes form long, complex arms with what can best be described as filigree. and yet, the filigree on opposite sides of the snowflake are also symmetric - that's shown even in these photos.

so what i want to know is how does crystal faces on opposite sides of the snowflake 'know' to grow symmetric filligree? what mechanism is there that allows one crystal face of a snowflake to 'know' what the other crystal faces are doing and so grow identical structures?

Re:why are snowflakes symmetric?

[exploder]

I think it's because (snowflakes being quite small) all sides experience nearly identical conditions of temperature, humidity, whatever-else-affects-crystal-growth at nearly identical times.

Re:why are snowflakes symmetric?

[Anonymous Coward]

I think it's because (snowflakes being quite small) all sides experience nearly identical conditions of temperature, humidity, whatever-else-affects-crystal-growth at nearly identical times.

I'm a cloud physicist and you, sir, are correct, identifying not only the reason for the symmetry (uniform conditions across the crystal over relevant time scales) but also the two controlling factors of temperature and humidity (well, humidity above saturation). Well done. Let me buy you a virtual beer.

The diversity of shapes is what's really cool. As far as I know (and this isn't my area) we have a phenomonology for habit (we know what shapes are most likely at a given temperature and humidity, for example) but we don't have a good theory to explain why that's so.

Bad summary

[TrumpetPower!]

First, 1/200s is a very common shutter speed, yes, but most cameras can shoot at at least 1/2000s and most high-end cameras can shoot at 1/8000s...assuming, of course, you have enough light.

Most high-speed stills photography is actually done with a slow shutter speed; perhaps even a shutter left open for a couple seconds. Motion is stopped by the short duration of the flash burst. And with, for example, a Canon 580 EX II flash, you can get a 1/35,000s flash duration. Granted, this will be at minimum power...but they're operating at macro distances, where you can put the flash head almost on top of your subject and still overpower the subject with light.

Don't get me worng; this team is doing some nifty stuff. But it's also something that most professional photographers could easily replicate with the equipment they already have -- and that anybody who specializes in macro photography will probably already plan on playing around with next winter after reading this article.

What the team is doing that's interesting isn't the photography. It's the 3D reconstruction and subsequent analysis and modeling. Making it seem that it's about the photography, which is the easy and inconsequential part, really detracts from the good stuff.

Cheers,

b&