Why does the snowball roll bigger?
The bigger the snowball can roll, the more often it is explained that the snowball relies on the effect of the sticky force, during rolling, snow on the ground adheres to it. But in reality it is not completely so. In the cold winter, the snowball and the snow itself on the ground were not wet. There is not much impact between them. So, what is the main cause of the larger snowball rolling?
It turned out that, only under standard atmospheric pressure did the ice and snow begin to melt at 0 ° C. Scientific experiments show that, when the ice is subjected to a greater pressure, its melting point drops accordingly. When the pressure is increased by 135 times the standard atmospheric pressure, snow and ice can melt at -1 ° C. Because of that physical characteristic of ice, the snowball during rolling became bigger and bigger.
As we begin to soften the snow, tightening the pressure between the snow wings, the melting point of the snow is lowered. In conditions where the outdoor temperature is lower than 0 ° C, snow can also melt into water. But once the pressure is abolished, the water at temperatures below 0 ° C will freeze again. As such, about squeezing the snow in his hand, the snow wings were shaped into a snowball. As the snowball rolls around on the ground, the snow fields that are crushed on it will melt first, then freeze, and stick to the snowball. According to the rolling speed of the snowball, the more snow on the ground attached to the globe, the bigger the snowball rolled.