This means that in a gm solution of salty water, there is 3. Or, put another way, one litre of seawater contains 35 grams of salt - that is approximately six teaspoons. The other salts are made up of chlorine, sodium, magnesium, sulphur, calcium, and potassium. Salt water has more mass in it than fresh water. That mass would be the salt, which makes the mass of water greater, without adding much to its volume. Increasing the mass by adding salt increases the density. Seawater is a little bit more dense than fresh water so it sinks beneath freshwater.
This means that when rivers flow out into the sea the river freshwater floats on top of the sea water. However when the wind blows and the sea becomes rough, the two waters become all mixed up. The winters in the Arctic and the Antarctic are extremely cold. The surface waters of the Arctic and Antarctic oceans become very cold and finally freeze. When seawater freezes to form sea ice, salt is squeezed out and moves down into the water.
This means that sea ice is made up of mostly fresh water. The water just below the sea ice is saltier and more dense than the water below. Because it is more dense, it sinks.
The water that sinks is replaced by surface water that comes from areas closer to the equator where it is warmer. One litre of seawater contains 35 grams of salt - that is about six teaspoons. Salt water has a greater mass than fresh water. Seawater is more dense than fresh water so it sinks below freshwater. The winters in the Arctic and the Antarctic are very cold.
The surface of these waters can become so cold that they freeze. Warm water is less dense than cold water so rises above cold water as seen in this photo. Image: George Mehler and Jared Hottenstein. The ocean can be divided into three layers based on temperature: A mixed relatively warm layer, a thermocline where water cools with depth and a cold deep water layer.
Image: University of Waikato www. Antarctic sea ice is made up of mostly fresh water. In most of the ocean, the water becomes colder with increasing depth. At meters, 6, feet the global average temperature is about 2. SST has been measured all over the world for more than a hundred years by ocean-going ships.
Below the sea surface, historical measurements of temperature are far sparser, and the warming is more gradual, about 0. The long-term increase of SST and the warming over the whole water column are both important in the physics of climate.
Sea surface temperature is an important factor because it controls the exchange of heat between the ocean and the atmosphere and in so doing, influences the temperatures experienced on land. The oceans have much greater capacity to store heat than the atmosphere, and ocean currents and mixing carry heat away from the sea surface into the deep ocean.
This is equivalent to having each 10 meter-by meter area on Earth continuously warmed by a watt light bulb. On time-scales of a decade or two, global SST fluctuates by about 0. That is the case in the most recent decade.
0コメント