Why Do Ice Cubes Float in Water?

课文

1. Most solids sink in their own liquid form, but ice is a rare exception because it becomes less dense when frozen.

   大多数固体会沉入自身的液态中，但冰是个罕见的例外，因为结冰后密度反而变小。

2. Water molecules form hexagonal crystals as they freeze, creating empty spaces that increase volume without adding mass.

   水分子结冰时形成六边形晶体，其间留下空隙，使体积增大但质量不变。

3. This expansion makes solid ice about 9% less dense than liquid water, so it naturally rises to the surface.

   这种膨胀使固态冰的密度比液态水低约9%，因此自然浮于水面。

4. If ice sank instead, lakes and oceans would freeze from the bottom up, making aquatic life nearly impossible in winter.

   如果冰会下沉，湖泊和海洋将自下而上冻结，冬季水生生物几乎无法存活。

5. The floating layer of ice also acts like an insulating blanket, slowing further heat loss from the water below.

   浮在水面的冰层还像一层保温毯，减缓下方水体的热量散失。

6. Scientists call this property 'anomalous expansion of water', and it’s essential for Earth’s climate and ecosystems.

   科学家称这一特性为‘水的反常膨胀’，对地球气候和生态系统至关重要。

7. You can observe this by freezing a plastic bottle full of water — it bulges or even cracks as ice forms.

   你可以用装满水的塑料瓶做实验：结冰时瓶子会鼓胀甚至开裂。

8. Unlike most substances, water reaches its maximum density at 4°C, not at its freezing point.

   与多数物质不同，水在4°C时密度最大，而非凝固点。