Artist Andrew Goldsworthy had a secret stash of snowballs. They were big and bold, and made quite a splash when he surreptitiously placed 13 of them on London streets in the middle of summer in 2000.  

These were not just any old snowballs. They were works of art made during the winter with natural materials rolled within their one-ton bulk. They were stored until summer and then Britons were treated to the big reveal as they melted on a warm, late June day, exposing their hidden treasures.  

While not an artist of Mr. Goldsworthy’s fame, I was moved to create a snowball during last Saturday’s snow flurry. Mine was neither large nor full of mysterious materials. In fact, it was barely a ball, with the fluffy snow refusing to pack into a simple sphere. The snow simply escaped through my gloved fingers.  

Taking off my mittens and trying to use the warmth of my hand didn’t lead to any additional success. This is because it is generally pressure, not heat, that makes snow bond.    

The failure was, in other words, not my fault. Snow can be fickle but its physics cannot be changed. Unusual among most substances is that water is actually less dense in its solid state than it is in its liquid state. Think of ice cubes floating in a glass of water and compare that to any metal cube placed in a vat of its own molten liquid. This density distinction is because of the water molecules’ shapes and properties that disallow the formation of a dense solid crystal. Because of this fact, the compression of snow causes it to liquefy and therefore shrink.   

Which brings us back to me making that ball of snow. It was the pressure that was key; not the temperature of my hands. As you use your hands to squeeze the crystals together, the pressure causes them to melt slightly, and bonds are formed between the crystals. But when pressure is removed, the crystal refreezes and the ball stays together. This process of bonding is called sintering.  

Sintering can be inhibited by certain conditions and that is what can lead to snowball formation failure. Whether it is wet or dry snow can be a factor. Wet snow is good: sticky snow forms in warmer temperatures — around freezing — that encourage the big, heavy flakes that easily bond. The wet snow is great for snowball, snow house and snow people creations.   

Dry snow, on the other hand, is what led to the unstickable situation experienced last weekend. The fluffy snow is formed when temperatures are much lower than 32 degrees Fahrenheit and the dry, cool air produces the powdery stuff that skiers and snowboarders prefer. Snow at subfreezing temperatures contains no liquid water for bonding, and even your most fervent squeezing won’t make ‘em stick.  

The light dusting of snow melted quickly on Sunday, though we might get more this season with which to experiment. For now, I am left with a memory of the beauty and fragility of Saturday’s snowfall and its inability to form a ball. No matter the quality of quantity of the flakes, or their ability to compress, what remains — as with art — is the knowledge that the pursuit of snowball perfection is a craft that sometimes depends also on science.  

Suzan Bellincampi is Islands director for Felix Neck Wildlife Sanctuary in Edgartown and the Nantucket Wildlife Sanctuaries. She is also the author of Martha’s Vineyard: A Field Guide to Island Nature and The Nature of Martha’s Vineyard.