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Anyone Else Catch that Wild “Steaming” Snow Last Night?

by Prince Of Petworth February 4, 2016 at 10:10 am 20 Comments


“Dear PoPville,

On my walk home from work last night, I noticed what I found to be a bizarre phenomenon. It was quite foggy which created an eerie, yet cool atmosphere. Then, as I was walking east on H street NW, heading towards 7th street, I noticed that most of the snow banks had steam billowing from them. It was much in the same way that you see steam come off of an athlete’s head in the cold weather. The pictures don’t quite do it justice, but you can definitely see it a bit (one of the pics looks like exhaust). Now I barely passed high school chemistry, but if a snow bank was steaming, wouldn’t that mean that the snow would have to be warmer than the air?”

steaming snow
Photo by PoPville flickr user Andrew Pasko-Reader

  • wdc

    Yes! I saw that and I’m glad you brought it up. Reminded me of the manure piles of my youth. Except not, because it’s not warmer than the air.
    Looking forward to the explanation from one of our scientifically savvy posters.

  • Isn’t that how last night’s fog was made?

    • …and I don’t mean completely, because I understand you also need moisture in warmer air, moving over cold ground

  • Michael

    This has been happening as the air has gotten much warmer and more moist over the last few days. Water vapor in the air condenses into the cloud you see when it is cooled by coming close to the snow and ice on the ground.

  • My dad always called it snow eater fog.

    • Beau

      that’s a great name for it!

  • Pixie

    Yes! All that fog and snow steam made for a really cool walk with the dog last night.

  • wdc

    It’s gonna go from solid form directly to gas.
    I can tell you it’s fairly rare and very unstable.
    Now if we can just keep it from exploding!

    • Real Genius

      sublimation indeed!

    • jst

      +1 for the real genius reference.

  • Petworthian

    On my way home on Rock Creek from Georgetown to Petworth at 10ish, it was amazing. Everything was foggy and you could see the snow piles melting

  • NewKidinBloomingdale

    I also did a bit of a double take when I saw the clouds of fog over the snow banks over the last couple days. But you’re right in observing that it can’t be steam coming from the snow since the snow is cold, not hot like boiling water. The difference here is that the water vapor hanging in the air as a little mini cloud above the snow banks is actually water that started in the warm humid air and is condensing after the snow makes the air colder. Warm air is able to hold more moisture than cold air (http://www.engineeringtoolbox.com/moisture-holding-capacity-air-d_281.html), so when the snow cools down the air directly surrounding it, that water has to go somewhere. This is the same phenomena that’s responsible for forming clouds in the atmosphere. (http://www.weatherwizkids.com/weather-clouds.htm)

  • stcohi

    I saw crews still hauling away snow piles on 14th street last night. I don’t see the point: The snow is rapidly melting or getting rained on. For what purpose would you put in the manpower and money to haul away snow that is only a day or two away from completely melting? These were not large snow banks, by the way.

    • AK

      “Creating” jobs.

  • zandunga

    It looked surreal. I saw it on my Nest camera when I turned my computer on last night.

  • Charles

    If a snow bank were “steaming,” it would have to be above the local boiling point of water, and would have a hard time being snow. Not all water vapor is steam.

  • jdre

    Y’all don’t really see a lot of snow, do ya?

    • wdc

      I grew up in snow country, and don’t recall having seen this before. Probably because it remained really damn cold all winter, none of this 60-degrees-three-days-after-a-blizzard stuff.

  • YES! I work out in the exurbs, surrounded by lots of fields, and it’s been super foggy like this for the past 3 days. Gorgeous and spooky.

  • pokerface

    A few days after the blizzard in 96′ the same thing happen albeit while we still had over a foot of snow on the ground all over. I literally watch a foot of snow melt right before my very eyes. Of course that set off major flooding coming down the Potomac from Great Falls. Georgetown, Haines Point and Old Town were a mess.


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