Is it Possible

[Rachel Chambers]

I am not sure exactly where to post this, so moderators feel free to move it to where it belongs.
I was just wondering if it is possible to have a "snowbow?" A rainbow but with snow.

 

[Susan Strom]

How funny. I ask that same question on my website, if "snowbow" is a technical term. Here is a snowbow from the Four Peaks Wilderness (Mazatzal Range winter 2003) during some snow flurries. It was very cold when I took these pictures.

And this is the mountain about 45 minutes later. The sun slipped further under the clouds at my back and made the mountain snow pink, then red. The angle of the sun just before this picture made the snowbow above.

 

[John Diel]

Not to down an Awesome photo (and it is!), but is this really a "Snowbow". I, of course, am no expert on the matter and certainly not an engineer or scientist by any stretch. However, What I see depeicted in the photo is Virga. At what point it moves from Frozen Precipitation to Liquid is a matter of debate. I believe you could have a "Snow Bow" if there is a certain amount of liquid water mixed in with the Frozen.

Here's my reasoning: Ice Crystals do not refract sunlght the same way water does. It does to a degree, hence, Sun Dogs and Sun Pillars and the like, but for a true "Rainbow" effect, I would think you would have to have a certain portion as liquid water.

These are only my thoughts on the matter and I could be totally "washed up"! Some of the Grads on the forum might be able to shed some better quality "light" on the subject.

Neat question too. I had never really thought about it. Susan. Keep 'em' coming on the photos. They are some awesome shots!

John

 

[Susan Strom]

Hi John, it was snowing, there was no rain there. It was very cold when I was in the canyon, I was in a duster but I was still freezing (and my camera was acting up, the shutter on one of my Ricohs gets sticky in very cold weather.)

The Four Peaks gets snowed on regularly each year about this time. It is a 7,600 ft desert mountain. The snow is very dry though. (If you want to see it fully decked out with snow look at

Mazatzal Snow 3/12/06

In the Mazatzal chase report the snow level came to 2,000 ft so you can imagine how Four Peaks got covered.)

Ice crystals make irridescence, also a rainbow effect, in cirrus clouds at high levels. Parhelia at the Arctic Circle form by direction/orientation of the ice crystals, making the mock suns.

It was too cold to be raining that day...although at the time I was wishing for a few degrees warmer!

Maybe there was some frozen rain too mixed in there. It didn't touch me so I couldn't tell, it was just floating by like some light feathers.

 

[John Diel]

Warm layer or air maybe? Hmmm... Sure enough, you have photographic and ground level experience of the moment and location that just shoots my theory down in flames.

I'll resort to my next SWAG.... "I dunno" :unsure:

 

[cdcollura]

Good day,

I believe the snowbow was not caused by snow but water droplets since it appears the rainbow was close to the cloud base, as snow cannot refract light the same way as droplets would to produce a rainbow. The water was most likely SUPERCOOLED, where it is still liquid below the freezing point of water.

This can be caused by two things, adding chemicals (salt, antifreeze, etc) to the water to lower its freezing point - But that is obviously not the case here - Or second, having small water droplets, held nearly spherical in shape by the surface tension of the water, and it it this surface tension that allows the water to remain liquid far below freezing (the crystal size of the ice "trying to form" is larger than the droplet itself) - and Voila - You have a rainbow (from the droplets of supercooled water) "embedded" in a shaft of snow!

The snow does not do much in the way of the rainbow, but the droplets (liquid supercooled water) mixed in with the snow and ice crystals refract light just like liquid water would above freezing, and that is what is producing the halo / rainbow.

 

[Jeremy Miller]

Good day,

I believe the snowbow was not caused by snow but water droplets since it appears the rainbow was close to the cloud base, as snow cannot refract light the same way as droplets would to produce a rainbow. The water was most likely SUPERCOOLED, where it is still liquid below the freezing point of water.

This can be caused by two things, adding chemicals (salt, antifreeze, etc) to the water to lower its freezing point - But that is obviously not the case here - Or second, having small water droplets, held nearly spherical in shape by the surface tension of the water, and it it this surface tension that allows the water to remain liquid far below freezing (the crystal size of the ice "trying to form" is larger than the droplet itself) - and Voila - You have a rainbow (from the droplets of supercooled water) "embedded" in a shaft of snow!

The snow does not do much in the way of the rainbow, but the droplets (liquid supercooled water) mixed in with the snow and ice crystals refract light just like liquid water would above freezing, and that is what is producing the halo / rainbow.
[/b]

Awesomely beautiful pictures!. The first picture is a beautiful display of snow (maybe virga, can't really say the snow isn't reaching ground, because I am now there) descending from cloud base and to the left you can see a refraction of light through the snow crystals. The second one I didn't notice any "snowbow" but really beautiful looking clouds at sunset. Living in central new york, south of syracuse in the valley surrounded by hill's. I am in a north facing 10 floor building for people with disabilities and seniors, I live
on the 6th floor and its such a beautiful view. Totally unobstructed view NW-N-NE good for spotting and
watching storms and also good for watching squall's moving into the area. Sometime's I can see the
entire structure of the snow squall's with the snow streaks coming down from the clouds. ITs awesome to
witness. I wish I lived on the 10th floor with a west and north facing window. You would be able to see
awesome detail with approaching squall line's from the west and also see lightning off on the horizon before
the storms even enter the county. Anyway, sorry for rambling on and on...



Great job Susan, keep up the superve work!.

Jer

 

[Glen Romine]

I don't think it is possible to have a snowbow work the same as a rainbow (namely refraction and reflection) - since if you understand how a rainbow works, you can't get the same behavior out of snow crystals. You can, however, get an optical effect that looks much like a rainbow, called diffraction (a good example is a sun dog, which most of us have seen at one time or another). The easy way to know which one you are looking at is if the sun is behind you, you are looking at a refraction/reflection process, whereas if the sun is in front of you (the snow/ice crystals are between you and the sun) you are probably looking at diffraction. Both can lead to rainbow-like colors, but with diffraction the warm colors (red) are on the inside.

As for what Susan has an image of - it would help to know the sun was behind her, but it appears that is the case based on the shadows, so she captured a refraction/reflection process, as in a rainbow. As to how the water drops came to be there - certainly a sounding would be needed to get much beyond wild speculation, but what can be said with confidence is that water drops were present. As for cdcollura's mixed phase argument, that's difficult if there is a mixure of super-cooled water drops and ice crystals - you'll end up with all ice almost immediately. Instead - you either have to start with liquid water only and little if any ice (which could be supercooled if cloud top temps were too warm to support homogeneous freezing), or have ice process in the clouds but melting to produce rain (and so no longer super-cooled unless it fell into another layer of sub-freezing air layer after melting). Given the top edge of the rainbow is rather diffuse but in definite sunshine, I'd tend to think snow falling out of the cloud was melting to produce the water drops needed for the rainbow. The location where Susan was at may have been at a higher elevation where temps were below freezing, so the local horizon was above the freezing level, but in the valley there may have been warmer temps that allowed for melting. Tough to know without more information. A nice image - but I don't think one of a snowbow. I'm not a microphysics expert - so perhaps someone with more expertise can shed more light on this.

Glen

 

[Saul Trabal]

Nice pics, Susan!

Yes, I've seen snowbows, and I've seen them during isolated, but rather strong snow squalls. Gorgeous.