Saline water freezes at a certain point based on its salinity. The freezing of more saline water is slower than the freezing of less saline water. A saline solution has a higher boiling point than fresh water. Over more saline water, evaporation is also less than over less saline water due to its effect on salinity. Seawater density is also greater when saline.
Factors Affecting Salinity of Ocean :
- Rate of evaporation:
- The ocean between 20°N and 30°N latitudes has more salinity than the temperate latitude ocean due to a higher rate of evaporation (because of high temperature).
- However, due to the considerations indicated in the next paragraph, this does not entail that tropical oceans will have more salinity.
- Amount of Freshwater Added :
- The places having high daily rainfall, high relative humidity, and addition by freshwater have low salinity.
- E.g. Oceans into which huge rivers like Amazon, Congo, Ganges, Irrawaddy, and Mekong drain have lower salinity.
- The Baltic, Arctic, and Antarctic waters have a salinity of <32 ppt because much freshwater is added from the melting of icebergs, as well as by several large poleward bound rivers.
- The Influx of River Water: Rivers reduce the salinity by diluting the salt concentration of the sea and ocean.
- If a number of rivers are flowing into a specific location of the ocean, then there is a high chance for low salinity.
- As big rivers contain a large amount of fresh water, which is enough to decline the salinity of the ocean.
- For example, Near the mouths of the Ganga-Brahmaputra, the Amazon, the Congo, etc., lower levels of salinity are found, and the effect of river water is more pronounced when it discharges into enclosed seas.
- Such as in the Gulf of Bothnia situated in the Baltic Sea, salinity reduces by five parts per thousand as river water adds in it.
- Ocean Currents:
- They affect the spatial distribution of ocean salinity.
- Oceanic currents affect the salinity by increasing and decreasing it.
- Oceanic currents have less impact on the enclosed sea’s salinity however the impact on the salinity of marginal seas with open sea ducts is significant.
- Atmospheric Pressure and Wind Direction:
- Anticyclonic conditions generally raise the salinity of the oceanic surface water when it has stable air and a higher temperature.
- At the high-pressure zone of subtropics, higher salinity can be observed.
- Winds and currents provide assistance in the redistribution of oceanic salinity.
- Global Warming:
- Global warming threatens the overall stability of ecological balance, not only salinity.
- It affects many factors such as temperature, ice melting, and many more, which directly and indirectly impact the salinity of seawater.
Frequently asked questions related to the factors affecting salinity:
Ques 1.How does evaporation affect the salinity of ocean water?
Answer: Evaporation plays a crucial role in increasing the salinity of ocean water. When water evaporates from the ocean surface, it leaves behind the dissolved salts, resulting in a higher concentration of salt in the remaining water. This process is particularly prominent in areas with high evaporation rates, such as tropical regions, leading to higher salinity in those areas.
Ques 2. How does freshwater input from rivers impact the salinity of ocean water?
Answer: Freshwater input from rivers can significantly affect the salinity of ocean water. Minerals and dissolved salts from the land are carried by rivers and introduced into the ocean. This freshwater input dilutes the seawater, lowering its salinity. This process particularly influences coastal regions as they receive significant freshwater discharge from rivers, resulting in localized decreases in salinity.
Ques 3. What role does precipitation play in influencing the salinity of ocean water?
Answer: Precipitation can affect the salinity of ocean water in several ways. Rainfall directly adds freshwater to the ocean, diluting the seawater and reducing its salinity. Additionally, precipitation can lead to increased runoff from the land, carrying dissolved salts into the ocean. Regions that experience high rainfall and freshwater input typically have lower salinity levels compared to arid or desert regions. The impact of precipitation on salinity varies geographically.