Final answer:
New cracks form in ice wedges every winter due to the expansion of water upon freezing and its subsequent contraction during thawing. This process of thermal expansion and contraction creates stresses within the ice, leading to the formation and enlargement of cracks.
Step-by-step explanation:
Each winter, new cracks form in ice wedges primarily due to the natural process of thermal expansion and contraction. Water expands when it freezes and contracts when it melts. During the winter months, as temperatures drop, water trapped in the ground freezes and expands, causing the ice to crack and form new wedges. This is similar to how unprotected pipes in houses break when water inside them expands upon freezing.
The cycle of freezing and thawing creates stresses within the ice, causing it to fracture and form new cracks over time. This process is exacerbated by the repeated thawing and freezing cycles, which can cause existing cracks to enlarge or new ones to form. Additionally, mudcracks display a similar behavior; when wet sediment dries out and shrinks, it forms cracks. Overall, the thermal expansion of water when freezing plays a crucial role in the formation of these ice wedges.