How Does a Snowball Form?

As you lift a snowball from the pile to throw it at your opponent, you stop to admire it. As you should! Many factors go into creating a snowball, after all, some of which you can’t control and others which you can. Exactly how does a snowball form?

The ideal snow for forming snowballs is about eight percent moist so the snow crystals can stick. The temperature should remain around 32 degrees Fahrenheit. To form a snowball with your hands, you grab deep into the snow and rotate until you feel pressure on the snowball.

In this article, we’ll talk a lot more about the temperature and weather requirements for forming snowballs as well as the technique you must employ for perfectly spherical snowballs. Make sure you keep reading! 

The Ideal Type of Snowfall for Snowballs 

The next time you stick your tongue out to catch the snow as it’s coming down, what lands in your mouth could be any one type of snow crystal. We’ve talked about this on the blog before, but we’re due for a recap.

Here are the types of snow.  

  • Graupel: Graupel is what falls when conditions outside turn sleet-like. It’s not quite sleet and it’s not hail either, as graupel is mostly liquid water. The snow crystal will have a white middle. 
  • Powdery snow: Powdery snow is very loose, soft snow. Its free water content, which refers to how much moisture the snow contains, is around three percent. This snow doesn’t stick well on itself. 
  • Wet snow: When the snow falls heavier due to the increased free water content, it’s wet snow. The free water content is anywhere from eight to 12 percent to classify as wet snow. 
  • Very wet snow: When the free water content of snow is 13 percent or higher, then what’s fallen is very wet snow. This is slushy stuff and the opposite of graupel, and it’s heavy to boot!

Of the four snow types, which do you think is the best for making snowballs? It’s wet snow. Since we’re recapping, wet snow is like glue for snow crystals. The moisture allows the crystals to adhere both to themselves and to other piles of snow.

Wet snow is what you need to form a perfect snowball. More so than that, it’s what you use to make any snow structure, from snowmen to igloos to snow forts. It’s heavier than some of the other types of snow, but it’s got that perfect stick.

Powdery snow, on its own, is too loose and crumbly to be useful for forming snowballs. However, by wetting powdery snow, its free water content increases and it behaves a lot more like wet snow.

Graupel is not snowball-making snow. It’s not helpful for much of anything. To avoid being pelted, you should stay indoors while graupel falls.  Then shovel it as per usual when the storm ends. 

Very wet snow is similarly useless. The free water content is such that the snow falls apart in your gloved fist. All you can do is shovel the stuff. Moving very wet snow isn’t easy due to its weight, so take your time. 

how does a snowball form
what is a snowball

The Ideal Temperature for Snowballs

The type of snow that falls is but one of the trifecta of factors that can influence whether yours is the perfect snowball. Another very important factor is the temperature. 

For snow to form, the temperature must be at least 32 degrees. Once snow blankets the ground (preferably inches or even feet of it), the temperatures must remain around at that 32-degree mark or the snow will begin to melt.

Even if temperatures are at 35 degrees versus 32 degrees, the three-degree difference in temperature will impact the structural integrity of the snow. It won’t melt to a noticeable degree, but the snow won’t be as solid as it would be if it was several degrees colder.

As you can imagine then, when the temperatures are even warmer, snow melts at a more accelerated rate. Although a 40-degree day might still feel cold to you, by that point, the snow is becoming slushier and slushier. If the temps reach the 50s, then most of the snow on the ground will begin disappearing. 

As detrimental as high temperatures can be for snow, when the temps are too low, the snow becomes hard to use as well. The closer the temperatures get to zero degrees, the less free water content the snow has. 

The snow will feel hard and crusty. It could be somewhat powdery as well. Wetting this snow will make it more pliable, but you won’t want to spend more time outdoors than necessary since it will be very cold. You especially won’t be in the mood to run the tap. 

The Ideal Technique for Forming Snowballs

You’ve got good temperatures outside in the low 30s and the snow that’s fallen is wet (or you’ve made it that way with a tap or a bucket). The third part of the snowball-forming equation is your technique. 

We wrote a detailed post about how to make the perfect snowball that we’ll recap for you in this section. 

The technical process of making a snowball is sintering, which means taking something that’s a solid mass and compacting it until it nearly reaches its melting point. Before you begin the sintering process, we recommend two things.

First, you should always have on a pair of waterproof winter gloves. Second, never use surface snow. It’s dirtier and looser compared to the snow that’s a couple of inches deep into the snow pile.

Keeping that in mind, here are the steps to make a great snowball.

Step 1

When your hands are a few inches deep into a snow pile, grab only a handful of snow. The larger the snowball, the heavier, and that means it’s unstable. It’s okay if the amount of snow you grab is slightly more than a fistful, as you’ll whittle your snowball down, but you don’t need armfuls. 

Step 2

Cup both hands and feel the snow. Does it have any chunks of ice in it? If so, then dispose of it and reach for another handful of snow, ideally from a different snow pile. You should do the same if you feel rocks in your snow, even if those are small pebbles.

When you throw a snowball at someone with rocks and/or ice in it, you can seriously hurt the other person. That’s why one of the top snowball fight rules is to only use pure snow. That said, if you’re using your snowballs for a snowman, then it matters less if the snow has rocks or ice in it. 

Step 3

Both your hands should contain about a fistful of snow, as we said. Now you want to smoosh those two handfuls together until they form one large ball-like snow structure. 

As soon as you combine the two fistfuls of snow, begin rotating the loose snowball immediately so it will solidify and not crumble into pieces in your arms.

Rotating is a process in and of itself, and here’s how it goes. Keeping your hands cupped, you move the snowball about in your hands without crushing it. 

The best way we can describe it is this: imagine you found a small bird and you were trying to keep it warm. You’d move it in your hands without ever applying pressure. That’s the technique you should use to form a snowball.

Step 4 

It takes practice to get good at rotating a snowball, but you’ll know you’re doing it right when you can rotate without thinking about it. There’s a natural rhythm to it that’s a consistent pace.

Step 5

You can’t just keep rotating forever though. As you hit your stride, it’s time to put pressure on the snowball. Don’t slow down your rotating pace; just press harder on the snowball as you rotate it from hand to hand.

How hard you apply pressure is critical. You don’t want to accidentally squish your snowball, as then you’d have to start all over. You’re not testing your strength or mettle as you form a snowball.

Don’t go so gently though that you’re not getting anything done. Your snowball needs the pressure to firm up, after all!

Step 6

As you rotate the snowball harder, you’ll eventually feel resistance. The sounds of you applying pressure on the snowball–which yes, it is indeed audible–could grow louder. These are clear signs that you’re rolled the snowball enough. 

If you keep going now, you could squeeze the life out of your snowball, causing it to crumble in your hands. Stop rotating it, open your palm, and clean up the snowball so it’s completely cylindrical. 

Step 7

Now take everything you’ve learned in forming the perfect snowball to make another one, then another one until you have enough snow for a fun-filled snowball fight with the neighbors!  
Visit Our Winter/Snow Page for More Great Content!

Visit Our Winter/Snow Page for More Great Content!

Final Thoughts 

What causes a snowball to form is a combination of weather and technique. 

You ideally need wet snow (or powdery snow that you can make wet) as well as temperatures of 32 degrees or under. You also must perfect your snowball forming technique. As you do it more and more, you’ll become a natural. Don’t be afraid to mess up, as there’s plenty more snow for you to use. Good luck!

Geoff Southworth

I am a California native and I enjoy all the outdoors has to offer. My latest adventures have been taking the family camping, hiking and surfing.

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