<p>Ice can grow up from the ground in the form of needle ice. The formation requires  sufficient moisture in the ground. According to the <a href="https://nsidc.org/cryosphere/frozenground/how_fg_affects_land.html">National Snow and Ice Data Center (NSIDC)</a> site needle ice can grow up to 40 cm in length. Needle ice are thin crystals of ice and has a very distinct look. A search on <em>Needle Ice</em> provides a wealth of examples of needle ice, note that all pictures are not relevant! </p>

<p>Needle ice can also form from plants if suddenly subjected to very low temperatures and where moisture in the plant has limited escape possibilities.</p>

<p>The picture in the post is, however, not needle ice, it is clearly a form of icicle. In fact the common icicle is reminiscent to a stalactite forming from a cave ceiling. Corresponding to the stalactite, a stalagmite forms on the floor. The ice form on the picture is a <em>stalagmite</em> form, created by water dripping from a structure down onto the ground in sub-freezing temperatures (credit to geotheory).</p>

CC BY-SA 3.0
2015-01-12T02:56:56.327Z
*"Note that **not all** pictures are relevant"*? Also, you might be better off including a good example image, than telling people to search. The picture is *not* a stalagmite - it's on concrete, out in the open - there's nothing to drip by.
naught101
CC BY-SA 3.0
2015-01-12T08:15:38.020Z
The point is that features like this can result from objects, for example, vehicles, that have since been moved. The fact that it is on concrete and in the open is completely irrelevant. The similarity to a stalagmite concerns the process of gradual growth through addition of new material, in this case ice, on the surface, nothing else.
Peter Jansson
CC BY-SA 3.0
2015-01-12T10:57:48.923Z
I agree that you *could* find an icicle in a car park, after a car dripped on the ground (although in most cases the car is likely to freeze first). I was referring to the *"clearly a form of icicle"* - to me, it doesn't look anything like one - an icicle would be somewhat conical, and would likely remain so while it melted.
naught101
CC BY-SA 3.0
2015-01-09T10:47:35.000Z
2015-01-09T10:47:35.000Z
Peter Jansson
<p>It's called an ice spike. Not fully understood, can form on any surface of frozen water. my curiosity was peaked when one formed in a cup of water in my car. Scientists can't really say why it happens yet. </p>

CC BY-SA 3.0
2017-01-02T12:19:45.540Z
According to [this page](http://www.its.caltech.edu/~atomic/snowcrystals/icespikes/icespikes.htm) the process of ice spike formation seems to be well understood.
daniel.heydebreck
CC BY-SA 3.0
2017-01-01T15:49:37.347Z
2017-01-04T09:50:20.727Z
2017-01-04T09:50:20.727Z
Delane James Taylor Byrt
<p>If there is enough water underground, in a sealed reservoir (like under the concrete in the picture), as that water freezes, it will expand, putting pressure on what ever water is left unfrozen. That water will be squeezed out through what ever cracks it can find - in this case, upwards. Because the water is already near-freezing (perhaps even slightly below, if it's super cooled), it will freeze <em>very</em> quickly when it hits the air (which will be much colder than the ground, late at night). But if there is still water being pushed up from below, that ice will have to move out of the way (it's weaker than concrete). The friction of the flow of cool upwards might warm it just enough to keep it liquid, and the "stalagmite" will end up with a hollow core that the water is being pumped through, and that structure can just keep building on itself, until it is toppled by wind or gravity.</p>

<p>The picture is a bit grainy, but it looks like that's what's happened there. It also looks like the side of the hollow "stalagmite" has fallen off up the top, and released a bit of the remaining water (or maybe it just melted in the sun).</p>

<p><strong>Edit:</strong> Hah, I knew I'd seen this somewhere before - in my freezer! <a href="http://www.its.caltech.edu/~atomic/snowcrystals/icespikes/icespikes.htm">This page</a> describes how <strong>Ice spikes</strong> form - I basically got it right. It seems that they're more likely to form with de-mineralised water, and the temperature has to be within certain narrow limits.</p>

CC BY-SA 3.0
2017-01-01T22:45:45.870Z
You can also get hoar frost which is caused by near freezing air but below freezing surfaces. It forms more like a crystal growth from ambient humidity.
John
CC BY-SA 3.0
2015-01-09T03:06:43.490Z
2015-01-09T03:40:08.993Z
2015-01-09T03:40:08.993Z
naught101
<p>The other day a friend of my dad's showed him a picture of an icicle that appeared to be "growing" upwards out of a crack in a sidewalk. There were no roofs, overhangs or vehicles parked near by... It looked like a stalagmite you would see in a cave. It looked something like this<sup>*</sup>:</p>

<p><img src="https://i.sstatic.net/870wo.jpg" alt="ice stalagmite">.</p>

<p>How could this happen? </p>

<p><sup>* Note that this is not the actual icicle, I used this picture for an example.</sup></p>

CC BY-SA 3.0
2015-01-09T21:48:28.460Z
https://en.wikipedia.org/wiki/Ice_spike
Nick T
CC BY-SA 3.0
2015-01-10T01:21:04.137Z
@ruakh - No, it's an ice spike. They are cool, literally and figuratively.
David Hammen
CC BY-SA 3.0
2015-01-10T02:06:29.697Z
@ruakh Well, since it was a sidewalk there likely weren't any vehicles nearby at any point.
L.B.
CC BY-SA 3.0
2015-01-10T02:14:06.733Z
@ruakh Ah... Sorry about that :) I used this for an example. This isn't the original.
L.B.
CC BY-SA 3.0
2015-01-16T13:20:20.813Z
That photo looks like a parking lot.  In which case, it would have been a car sitting there, dripping water.  The picture may be a bit misleading, since that doesn't look like what you are describing.
Richard
CC BY-SA 3.0
2015-01-16T16:26:09.257Z
@Richard I couldn't find a picture of one "growing" from a side walk and so I needed this as an example.
L.B.
<meteorology><glaciology><ice>
How would an icicle "grow" upwards?
L.B.
# How would an icicle "grow" upwards?

(Asked by: username_0 on 2015-01-09)

The other day a friend of my dad's showed him a picture of an icicle that appeared to be "growing" upwards out of a crack in a sidewalk. There were no roofs, overhangs or vehicles parked near by... It looked like a stalagmite you would see in a cave. It looked something like this\*:

![ice stalagmite](https://i.sstatic.net/870wo.jpg).

How could this happen?

\* Note that this is not the actual icicle, I used this picture for an example.

**Tags:** meteorology, glaciology, ice

> **Comments:**
> **username_1**: https://en.wikipedia.org/wiki/Ice_spike  
> **username_2**: @ruakh - No, it's an ice spike. They are cool, literally and figuratively.  
> **username_0**: @ruakh Well, since it was a sidewalk there likely weren't any vehicles nearby at any point.  
> **username_0**: @ruakh Ah... Sorry about that :) I used this for an example. This isn't the original.  
> **username_3**: That photo looks like a parking lot.  In which case, it would have been a car sitting there, dripping water.  The picture may be a bit misleading, since that doesn't look like what you are describing.  
> **username_0**: @username_3 I couldn't find a picture of one "growing" from a side walk and so I needed this as an example.  

---

## 3 answers

### Answer by username_5 on 2015-01-09. Score: 27 | Accepted answer

If there is enough water underground, in a sealed reservoir (like under the concrete in the picture), as that water freezes, it will expand, putting pressure on what ever water is left unfrozen. That water will be squeezed out through what ever cracks it can find - in this case, upwards. Because the water is already near-freezing (perhaps even slightly below, if it's super cooled), it will freeze *very* quickly when it hits the air (which will be much colder than the ground, late at night). But if there is still water being pushed up from below, that ice will have to move out of the way (it's weaker than concrete). The friction of the flow of cool upwards might warm it just enough to keep it liquid, and the "stalagmite" will end up with a hollow core that the water is being pumped through, and that structure can just keep building on itself, until it is toppled by wind or gravity.

The picture is a bit grainy, but it looks like that's what's happened there. It also looks like the side of the hollow "stalagmite" has fallen off up the top, and released a bit of the remaining water (or maybe it just melted in the sun).

**Edit:** Hah, I knew I'd seen this somewhere before - in my freezer! [This page](http://www.its.caltech.edu/~atomic/snowcrystals/icespikes/icespikes.htm) describes how **Ice spikes** form - I basically got it right. It seems that they're more likely to form with de-mineralised water, and the temperature has to be within certain narrow limits.

> **Comments:**
> **username_8**: You can also get hoar frost which is caused by near freezing air but below freezing surfaces. It forms more like a crystal growth from ambient humidity.  

---

### Answer by username_4 on 2015-01-09. Score: 11

Ice can grow up from the ground in the form of needle ice. The formation requires sufficient moisture in the ground. According to the [National Snow and Ice Data Center (NSIDC)](https://nsidc.org/cryosphere/frozenground/how_fg_affects_land.html) site needle ice can grow up to 40 cm in length. Needle ice are thin crystals of ice and has a very distinct look. A search on *Needle Ice* provides a wealth of examples of needle ice, note that all pictures are not relevant!

Needle ice can also form from plants if suddenly subjected to very low temperatures and where moisture in the plant has limited escape possibilities.

The picture in the post is, however, not needle ice, it is clearly a form of icicle. In fact the common icicle is reminiscent to a stalactite forming from a cave ceiling. Corresponding to the stalactite, a stalagmite forms on the floor. The ice form on the picture is a *stalagmite* form, created by water dripping from a structure down onto the ground in sub-freezing temperatures (credit to geotheory).

> **Comments:**
> **username_5**: *"Note that **not all** pictures are relevant"*? Also, you might be better off including a good example image, than telling people to search. The picture is *not* a stalagmite - it's on concrete, out in the open - there's nothing to drip by.  
> **username_4**: The point is that features like this can result from objects, for example, vehicles, that have since been moved. The fact that it is on concrete and in the open is completely irrelevant. The similarity to a stalagmite concerns the process of gradual growth through addition of new material, in this case ice, on the surface, nothing else.  
> **username_5**: I agree that you *could* find an icicle in a car park, after a car dripped on the ground (although in most cases the car is likely to freeze first). I was referring to the *"clearly a form of icicle"* - to me, it doesn't look anything like one - an icicle would be somewhat conical, and would likely remain so while it melted.  

---

### Answer by username_6 on 2017-01-01. Score: -2

It's called an ice spike. Not fully understood, can form on any surface of frozen water. my curiosity was peaked when one formed in a cup of water in my car. Scientists can't really say why it happens yet.

> **Comments:**
> **username_7**: According to [this page](http://www.its.caltech.edu/~atomic/snowcrystals/icespikes/icespikes.htm) the process of ice spike formation seems to be well understood.  

---

