discuss: The relationship between specific heat of seawater and temperature and salinity

1. Properties of pure water. Water molecules are polar molecules and will produce four characteristics of the association phenomenon of water molecules.: (1) Strong solubility, high salinity of seawater (2) Strong heat absorption capacity, large specific heat capacity and specific latent heat of evaporation (3) Abnormal density, maximum density at 4°C (4) High friction between wind and water surface, large waves and ocean circulation 2. Salinity Salinity: The number of grams of solid material dissolved in one kilogram of seawater is generally recorded as S. 1 kilogram of seawater contains 35 grams of salt, which is recorded as S=35. History of Salinity Absolute Salinity: Salinity calculated based on "chlorine degree" = 1.80655 × chloride degree, recorded as 35‰. practical salinity: The salinity calculated based on "conductivity" is directly recorded as S=35, and ‰ is no longer used. 3. Thermal properties heat capacity: The heat absorbed when the temperature of sea water increases by 1K. Specific heat capacity: Heat capacity per unit mass of sea water. (The specific heat capacity of seawater is large, making the temperature of seawater change slowly) Specific latent heat of evaporation: The amount of heat required to evaporate 1kg of sea water. saturated vapor pressure: The pressure when water molecules escape from the sea and return to the sea to reach dynamic equilibrium. The specific latent heat of evaporation of water is the largest among all substances, and the saturated vapor pressure of seawater is small, which restricts the evaporation of seawater. adiabatic change: The increased sinking pressure of seawater microclusters causes their volume to shrink. The work done by external force on seawater microclusters increases the internal energy of seawater, causing its temperature to rise. ； On the contrary, when it rises, the temperature decreases. abyssal basin: The water temperature at the site rises slowly as the water depth increases. On-site temperature and temperature potential distribution in the Mindanao Trench (redrawn according to Pickard, 1979) Potential temperature: Seawater microspheres rise from a certain depth in the ocean to the temperature of the sea surface. (In the deep and bottom layers of the ocean, pressure has a greater impact on seawater temperature. When identifying water masses, it is often necessary to use potential temperature instead of on-site water temperature) 4. Density Density (mass per unit volume) Specific volume (density derivative) The concept of density excess: 5. The density of seawater equation of state is not easy to measure. It can be calculated indirectly through salinity, temperature, and pressure using the seawater equation of state (an equation that describes the relationship between seawater state parameters). An atmospheric pressure international seawater equation of state: High-pressure international seawater equation of state: Distribution rules of seawater temperature: The same sea area, different seasons in summer (high water temperature) and winter (low water temperature). Horizontal distribution rules. In the same season, different sea areas, high latitudes (low water temperature) and low latitudes (high water temperature). Warm currents flow through (high water temperature) at the same latitude. Cold currents flow through (low water temperature). Vertical distribution rules.: From the surface layer to the deep layer, the water temperature gradually decreases, and there is almost no change below 1000 meters. Distribution rules and influencing factors of seawater salinity: Influencing factors Sea area Factor 1 Factor 2 Factor 3 Factor 4 Red Sea √ √ × √ Baltic Sea √ √ × √ Hypothetical lake (saltwater lake) 1. Law: It decreases from the subtropical sea areas of the northern and southern hemispheres to high and low latitudes on both sides respectively. ①The reason why subtropical sea areas have the highest salinity: High temperature and high evaporation ； Controlled by subtropical high pressure, downdrafts dominate and precipitation is low. ②Reasons for lower salinity in equatorial sea areas: The equatorial low pressure controls the evaporation, but the precipitation is greater. ③Reasons for low salinity in high latitude sea areas: Low temperature, low evaporation ； The temperate rainy zone is filled with water from many rivers. ④The reason why the salinity of 60°N is lower than that of 60°S sea area: The northern hemisphere has a large land area and a lot of river water. 2. Main factors affecting seawater salinity: ①Climatic factors - The level of seawater salinity mainly depends on climatic factors, that is, the relationship between precipitation and evaporation. When precipitation is greater than evaporation, salinity is lower, and vice versa. ②Ocean current factors - in sea areas at the same latitude, warm currents pass through and the salinity is relatively high. ； The cold current passes through and the salinity is low. ③River runoff injection factors - sea areas where a large amount of river water flows into have low salinity. In addition, the amount of ice formation and melting in high-latitude sea areas (sea areas where ice formation occurs has higher salinity) ； In sea areas where ice melt occurs, the salinity is relatively low), the degree of closure of the sea area (the stronger the sealing degree of the sea area, the salinity will tend to be higher or lower), the amount of exchange with seawater in nearby sea areas, etc. can also affect the salinity of seawater. Each factor has different changes in time and space, so the salinity of seawater also has time and space differences. 3. Methods to analyze factors affecting seawater salinity: ①For sea areas at the same latitude, the relationship between precipitation and evaporation in each sea area is mainly considered. ② For sea areas at different latitudes, the influence of cold and warm currents is mainly considered. ； Secondly, the amount of river runoff injection in coastal areas ； In high-latitude sea areas, ice formation and melting conditions must also be considered. highest sea area: The Red Sea is located in the subtropics, with sparse precipitation, strong evaporation, and little freshwater inflow from the land. The water area connected to the outer ocean is narrow, reaching 4.1%. The lowest sea area: Baltic Sea. reason: Temperate maritime climate, with large amounts of fresh water flowing into rivers ； The latitude is higher, the evaporation is small, and the water area connected to the outer ocean is narrow. Not more than 1%. 1. Seawater temperature in the same sea area, different seasons in summer (high water temperature) and winter (low water temperature). Horizontal distribution pattern. In the same season, different sea areas, high latitude (low water temperature) and low latitude (high water temperature). Warm current flows through the same latitude (high water temperature). Cold current flows through (low water temperature). Vertical distribution pattern.: From the surface layer to the deep layer, the water temperature gradually decreases, and there is almost no change below 1000 meters. 2. Salinity distribution rules of seawater: Ocean - nearshore coastal