Final answer:
Needle ice contributes to the loosening of soil by forming ice structures that expand and disrupt the soil's compactness, leading to potential soil erosion.
Step-by-step explanation:
Needle ice plays an active role in the loosening of soil. Needle ice forms when the temperature of the soil surface drops below freezing, causing the water in the soil to move upwards where it then freezes upon contact with the cold air. This process results in the formation of needle-like ice structures that can physically disrupt the soil, causing it to become loosened. Over time, this can lead to soil erosion, as the soil is less compact and more susceptible to being washed or blown away.
The loose arrangement of molecules in ice, represented by red and white balls, leads to a lower density when compared to liquid water. As ice forms and expands within the soil, the increase in volume further contributes to the loosening and disruption of the soil structure.