Icicle growth more complex than you may think

Font Size:
Default font size
Larger font size

Posted: Thursday, January 30, 2014 7:08 am | Updated: 12:18 pm, Thu Jan 30, 2014.

Most people have never given much thought to how an icicle grows.  I suppose that's because most of us have filled the ice trays with water, tucked them into the freezer and in a short time have ice. Water plus cold air gives ice cubes, right?  Well yes, but it's much more complex than that.  In fact, the process has not been well understood until recently.

Icicle forming yesterday in Tallahassee

A lot of ice that formed in north Florida yesterday started as rain. That was because the air aloft was warmer than the air at the surface, which was below freezing. If the precipitation fell as snow or ice it would have to melt first before icicles could form.

Once the water contacts a frozen surface or an environment of freezing air, the water will freeze on an object. That forms the base of the icicle or the icicle root.  Then as successive sheets of water flow over the root, the warm water gives its heat to the surrounding layer of air in contact with the forming icicle and can then cool and freeze.

This transference of heat is the same principle Grandma used in winter to protect the food stored in the "root cellar" (if you lived up north in farm country). She would put a pan of water on the floor, which would freeze and give its heat to the air which would keep the veggies warm.

So as the air heats around the icicle it rises like a hot air balloon. This puts a thicker layer of warmed air near the top of the icicle. So as successive sheets of water fall down the icicle to freeze they are able to do so faster at the tip, where the air is cooler. Thus the icicle forms a long pencil like structure.

But that's just the beginning. The process is much more complex with different areas of the icicle growing at different rates and air getting caught up in the process, and temperature differences causing fractures.  Temperature and growth rates influence the crystal formation of the freezing water and rings and ridges form in these marvels of natures engineering.

Ripples in ice.
Credit:Craig Hansen

In the end, the complex physics is found to be described nicely by the math that describes the formation of those rock stalactites found in underground caves.  The process are different but the math can be transferred by changing a few numbers here and there.

So the next time you are visiting the frozen north take a moment to appreciate those frozen marvels; the icicle.

John Scalzi

More about

Rules of Conduct

  • 1 Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
  • 2 Don't Threaten or Abuse. Threats of harming another person will not be tolerated. AND PLEASE TURN OFF CAPS LOCK.
  • 3 Be Truthful. Don't knowingly lie about anyone or anything.
  • 4 Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
  • 5 Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
  • 6 Share with Us. We'd love to hear eyewitness accounts, the history behind an article.

Welcome to the discussion.


  • smorris posted at 2:56 pm on Sun, Feb 9, 2014.

    smorris Posts: 2

    Ah. Now I see what happened: the image is credited to Craig Hansen, who took a different icicle image on ThinkStock:

    The original Flickr image, which belongs to me, is here:

  • smorris posted at 2:45 pm on Sun, Feb 9, 2014.

    smorris Posts: 2

    This story discusses recent scientific work without linking or giving any credit to the authors of that work. Googling "icicle physics" will quickly turn up the origin of these ideas.

    One of the icicle images attached to this story was ripped off from Flickr and credited to someone else.


Right Now










Your Sarasota, Bradenton, North Port and Venice weather forecast is here. Along with the weather forecast, you'll get timely updates for temperature, humidity, and weather radar. Today's and tonight's Sarasota-Bradenton-Suncoast weather is at your fingertips with interactive radar online or in our Mobile Weather App. Our free downloadable Mobile Weather App will put vital information in your hands whether you're planning a day at the beach or in the event of severe weather.

Sarasota Manatee Bradenton Nokomis Charlotte Venice Suncoast Hurricane Center
Sarasota Bradenton Venice Manatee Charlotte Suncoast Weather Watchers