Ice in ice tray has a convex shape in the middle , Explain
Answers
it has a convex shape because only then you'll get the shape of the ice
Answer:
Explanation:
The process begins when surface water nucleates around irregularities where it meets the container wall and freezes inward. If the c-axis of the first crystal to form is not vertical, the basal plane intersects the surface along a line perpendicular to the c-axis and ice needles tend to propagate across the surface along this line. At the same time a curtain of ice grows down into the supercooled water along the basal plane. As the film of ice grows to cover most of the surface the crystals merge and become fixed rigidly in place and the sheet of ice continues freezing towards the middle until only a small hole remains unfrozen.[9] The crystallite curtains tend to join at an angle of 60 degrees and so the hole is often triangular,[6] although other geometric shapes are possible. The continuing expansion of the ice downwards into the water then squeezes the remaining water up through the hole and a convex meniscus is formed which bulges slightly higher than the surface of the ice. As the edges of the meniscus freeze they create a small dam which causes the water to rise higher and as it expands above the ice dam the edges freeze again to form another dam on top of the first one. If the rate of expansion of the water is the same as the rate of freezing at the lip of the hole then this process is continually repeated and successive layers form a tube of ice. The growth of the tube continues in this way until the tip seals over or until all the water is frozen.[9] The formation of ice spikes is related to the shape of the water body, the concentration of dissolved impurities, air temperature and air circulation above the water.[3] Spikes that grow from a crystallite formed below the surface of the water may project from the ice sheet at a steep angle, rather than perpendicular to it.[5]