![]() ![]() General Distribution of temperature ,Salinity and. Residence time of constituents in sea waterĪbsorption of radiation, eddy conductivity, diffus. Temperature and Thermal properties of sea waterĬolligative and Other properties of sea water The positive gradient is due to the isothermal layer with the velocity of sound increasing with depth because of increasing pressure. It is produced in the upper parts of the ocean. In addition to temperature, salinity and pressure, the characteristics of the bottom also influence the propagation of sound in shallow water through absorption, reflection, etc. the transmission of sound in the ocean is dependent on several environmental factors, the most important of which are the sound velocity distribution in the ocean, the depth and configuration of the bottom and the sediment characteristics of the bottom. The shallow water sound velocity profile is complicated by the effect of salinity variations caused by nearby sources of fresh water and contains several layers of different sound velocity gradients which have little temporal or spatial stability. At 20 C (68 F), the speed of sound in air is about 343 metres per second (1,125 ft/s 1,235 km/h 767 mph 667 kn ), or one kilometre in 2.91 s or one mile in 4.69 s. It is greatly influenced by surface heating and cooling, changes in salinity and water currents in these regions. The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. In the shallow waters of coastal regions and on the continental shelves, the sound velocity profile tends to be irregular and unpredictable. Assume that the speed of sound is 340 m/s. Calculate the speed of an aircraft with a mach number of 1.23. In this layer, sound velocity increases with depth due to the effect of pressure. Calculate the speed of sound in seawater at 20☌ given that the bulk modulus of seawater is 2.34×109 N/m² and its density is 1.025×10³ kg/m³. ![]() In the bottom layer i.e., below the thermocline layer and extending to the bottom of the ocean, temperature and salinity variations are again very negligible. ![]() Sound velocity decreases very rapidly in this layer due to temperature effect. In the middle layer or the thermocline layer, which extends from 100-150m depth to 1500m depth in the ocean, temperature decreases very rapidly. The sound velocity increases as depth increases in this layer due to the pressure effect. In the upper layer of the ocean, which extends from surface to 100-150m depth, temperature and salinity variations are negligible as a result of mixing of waters due to wind and waves. The vertical variation of sound velocity in the deep waters of the ocean can be divided into three layer. In the oceans, horizontal variations of sound velocity are smaller compared to vertical variations of sound velocity, because horizontal variations of temperature and salinity are smaller than the vertical variations. The increase in sound velocity is about 4.5m/sec for 1 oC increase in temperature about 1.3 m/sec for one-thousandth part increase in salinity and about 1.7 m/sec for 100m increase in depth. it increases with increasing temperature, salinity and pressure or depth in the ocean. Sound velocity in the ocean ranges from about 1,400 to 1,570 m/sec. ![]()
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