capilary毛细管.ppt

Life on earth began in the oceans about three billion years ago; 99% of the living space on earth is in the oceans; There are about five million (known) species in the oceans; Life in the oceans ranges from tiny plankton to giant whales. Water is a liquid at room temperature and has a relatively high freezing point; All living creatures need food to survive, but on many occasions the nutrients become available to living things only when they are dissolved by water. We can get a lot of nutrients by drinking soup. Plants can pull water up their roots via a capillary(毛细管) process. The salinity of sea water can affect the freezing point of water. Sea water has a lower freezing point, so even when the temperature of sea water falls below 0℃, sea water is still liquid. Ocean motion helps move nutrients around and adds energy to the marine ecosystems. Different marine creatures live in different levels of the ocean. (Because of the foods they need, sunshine etc.) The coastal areas are often neither too hot nor too cold. Ice floats on water. When the sea water in a container is evaporated (蒸发), there will be some salt left. Irrigate in winter can help raise the soil temperature. People swimming in the Dead Sea float; they can even read a paper while lying on their back in the water. These figures show how much water there is in parts of our body! * Unit 13 Period 1 Reading The Properties of Water Find out as many words and phrases as possible about water properties in the text. polar salinity density high heat capacity ocean motion ------ Water is a liquid at room temperature, and it has a relatively high freezing point. The reason why water can dissolve most substances on earth is that water has high heat capacity. Like all the other substances, water gets smaller (contract 缩小) when it freezes. Pure water has a higher freezing point and lighter than salt water. The salinity of the earth’s oceans is about 3.