Salinity Of The Oceans

The amount of dissolved salts per unit mass of water is referred to as salinity. The number of grams of dissolved salts in 1,000 grams of sea water is used to calculate salinity. Sea water has a salinity of 35 parts per thousand. It signifies that there are 35 grams of dissolved salts in one kilograms of sea water. The weight of the dissolved elements divided by the weight of the sample sea water is known as salinity. Salinity is defined as "the total amount of solid material in grams contained in one kilograms of sea water, expressed as part per thousand.

 

•    Oceanic salinity influences not just marine creatures and plant communities, but also oceanic physical qualities such as temperature, density, pressure, waves, and currents. The freezing point of ocean water is also affected by salt; for example, more saline water freezes more slowly than less saline water.

 

•    Saline water has a higher boiling point than fresh water. Evaporation is also influenced by salinity, with more saline water resulting in less evaporation. The density of sea water is also increased by salinity. This is why people rarely drown in seawater with a high salinity. Ocean currents are caused by changes in salinity.

 

•    Salinity falls from the equator to the poles on average. It's worth noting that the maximum salinity is rarely found near the equator, despite the fact that this region experiences high temperatures and evaporation. However, high rainfall reduces the relative proportion of salt. 

 

Four oceanic salinity zones can be recognized based on the latitudinal distribution of salinity, for example.

1.    Salinity-relatively low equatorial zones (due to excessive rainfall),

2.    Maximum salinity zone (200-300) in the tropical zone (due to low rainfall and high evaporation),

3.    A low-salinity temperate zone, and

4.    Minimum salinity zone in the sub-polar and polar regions.

 

Salinity is primarily influenced by four factors:

1.    Precipitation decreases salinity.

 

2.    Evaporation causes salinity to rise, and

 

3.    Salinity varies owing to the mixing of different types of water.

 

4.    In addition, oceanic salinity varies over time. The northern hemisphere's oceans reach their highest and lowest salinity levels in June (due to enhanced evaporation) and December (due to low evaporation).

 

•    Because both tendencies of increasing and decreasing salinity with increasing depths have been seen, no clear trend of salinity distribution with depth can be identified. 

 

•    For example, salinity near the Atlantic's southern edge is 330/00 at the surface, but it rises to 34.50/00 at 200 fathoms (1200 feet).

 

•    At a depth of 600 fathoms, the percentage rises to 34.75 percent. Surface salinity, on the other hand, is 370/00 at 20°S latitude, but drops to 350/00 as depth increases.

 

The following are some salinity vertical distribution characteristics:

1.    In high latitudes, salinity rises with depth, indicating that there is a positive relationship between salinity and depth due to denser water below.

 

2.    In middle latitudes, the trend of increasing salinity with depth is limited to 200 fathoms below the surface, after which it decreases with depth. Due to high rainfall and water transfer through equatorial currents, salinity is low at the surface at the equator, but higher salinity is noted below the water surface. At the bottom, it drops again. More research and data on salinity distribution at regular depths in various oceans and seas are needed to determine definite characteristics of vertical salinity distribution.

 

3.    The upper layer of oceanic water has the highest salinity. With increasing depth, salinity decreases. Thus, a transition zone known as the thermocline zone separates the upper zone of maximum salinity from the lower zone of minimum salinity. On average, high salinity is found above this zone, while low salinity is found below it. It may be remembered that this should not be taken as a general rule because the vertical distribution of salinity is very complicated.

 

•    Because dense water sinks below less dense water, seawater density plays an important role in causing ocean currents and circulating heat. The density of seawater is affected by salinity, temperature, and depth.

 

•    The density of a substance is a measure of how tightly it is packed into a given volume. The higher the density, the more stuff is packed in. The density of an object can be calculated by dividing its mass by its volume. 

 

•    Seawater is more than just water; it contains a plethora of chemicals. It is therefore denser than pure water. The density increases as the salinity rises.

 

•    Because salinity and temperature affect seawater density, it varies from place to place. This means that, depending on the density of the ocean, ships float higher or lower in the water.

 

•    Water with a high salinity content is denser. This is due to the fact that the water contains more salt. Water becomes less dense when it is heated to a high temperature. Water's molecules spread out as it warms, making it less dense. It gets denser as it gets colder. 

 

•    When most chemicals turn from a liquid to a solid, they become denser, but water is an exception. When liquid water solidifies into ice, it loses density. Water molecules arrange themselves into a rigid but open pattern when ice forms. Ice floats because its structure is less dense than liquid water. 

 

•    The density of deep water is higher than that of shallow water. Because of the weight of water above pushing down, the water molecules are packed together more tightly.

 

•    Water that is denser sinks below water that is less dense. The deep ocean currents that circulate around the world are driven by this principle. Seawater is dense enough to sink into the deep ocean and flow along the bottom of the basins due to a combination of high salinity and low temperature near the surface.

 

•    Waves are the energy that moves across the ocean surface, not the water itself. As a wave passes, water particles only travel in a small circle. 

 

•    The waves get their energy from the wind. Wind generates waves in the ocean, which then dissipate their energy along the shorelines. 

 

•    The stagnant deep bottom water of the oceans is rarely affected by surface water movement. A wave slows as it approaches the beach.

 

•    This is caused by friction between the dynamic water and the seafloor. The wave breaks when the depth of water is less than half the wavelength of the wave. 

 

•    The open oceans have the most powerful waves. Waves continue to grow in size as they move and absorb wind energy. 

 

•    The wind blowing against the water causes the majority of the waves. When a breeze of two knots or less blows across calm water, small ripples form and grow as the wind speed increases, eventually forming white caps in the breaking waves. Waves can travel thousands of kilometers before breaking and dissolving as surf on the beach.

 

•    The size and shape of a wave reveal its origin. Steep waves are relatively new and are most likely formed by local wind. 

 

•    Waves that are slow and steady are coming from far away, possibly from another hemisphere. 

 

•    The maximum wave height is determined by the wind's strength, which is determined by how long it blows and the area it blows over in a single direction.

 

•    Wind pushes the water body in its direction, while gravity pulls the crests of the waves downward. The wave moves to a new position as the falling water pushes the former troughs upward.

 

•    The water beneath the waves moves in a circular motion. As the wave approaches, things are carried up and forward, then down and back as it passes. 

 

1.    Wave crest and trough: A wave's crest and trough are the highest and lowest points, respectively.

 

2.    Wave height refers to the vertical distance between the bottom of a trough and the top of a wave's crest. 

 

3.    Wave amplitude is equal to one-half of the height of the wave.

 

4.    Wave period: The time between two successive wave crests or troughs as they pass a fixed point. 

 

5.    Wavelength: The distance between two successive crests on the horizontal plane. 

 

6.    Wave speed: The rate at which a wave travels through the water, measured in knots. 

 

7.    Wave frequency is the number of waves that pass through a given point in one second.

 

•    Ocean currents are similar to rivers that flow through the oceans. They represent a constant volume of water moving in a defined direction. 

 

•    A continuous, directed movement of seawater caused by forces acting on it is known as an ocean current. Ocean currents travel great distances and, when combined, form the global conveyor belt, which influences the climate of many of the world's regions. 

 

•    Ocean currents, in particular, have an impact on the temperature of the areas through which they pass. Warm currents travelling along temperate coasts, for example, raise the temperature of the region by warming the sea breezes that blow over them. The Gulf Stream, which makes northwestern Europe much more temperate than any other region at the same latitude, is perhaps the most striking example. Another example is Lima, Peru, which has a cooler (sub-tropical) climate than the tropical latitudes in which it is located due to the Humboldt Current's influence.

 

•    Gravity, wind friction, and water density variation in different parts of the ocean produce ocean currents, which are streams made up of horizontal and vertical components of the circulation system of the ocean waters. 

 

•    Ocean currents, like winds in the atmosphere, transport significant amounts of heat from Earth's equatorial areas to the poles, and thus play an important role in determining coastal climates. Ocean currents and atmospheric circulation also have an impact on one another.

 

1.    Factors affecting the earth's rotation: gravitational force and deflection force.

 

2.    Atmospheric pressure, winds, precipitation, evaporation, and insolation are all factors that originate in the sea.

 

3.    Sea-based factors include pressure gradients, temperature differences, salinity, density, and ice melting.

 

4.    Factors that influence ocean currents include coast direction and shape, seasonal variations, and ocean bottom topography.

 

•    In the northern hemisphere, currents flow clockwise, while in the southern hemisphere, they flow anti-clockwise. The Coriolis force, which is a deflective force that follows Ferrell’s law, is responsible for this. 

 

•    The northern part of the Indian Ocean, where the current changes direction in response to the seasonal change in the direction of monsoon winds, is a notable exception to this trend.

 

•    Warm currents flow towards cold seas, while cool currents flow towards warm seas. Warm currents flow on the eastern shores of lower latitudes, while cold currents flow on the western shores. 

 

•    In higher latitudes, the situation is reversed, with warm currents flowing along the western shores and cold currents flowing along the eastern shores. The currents are also controlled by convergence, where warm and cold currents meet, and divergence, where they diverge in different directions.

 

•    The shape and location of coasts have a significant impact on the direction of currents. The currents flow not only on top of the water, but also beneath it. Differentials in salinity and temperature cause these currents. The Mediterranean Sea's heavy surface water, for example, sinks and flows westward past Gibraltar as a sub-surface current.

 

•    The effects of off-shore Trade Winds are primarily responsible for the aridity of the hot deserts, which is why they are also known as Trade Wind Deserts. 

 

•    The world's major hot deserts are found on the western coasts of continents between 15° and 30°N. And S. They include the world's largest desert, the Sahara (3.5 million square miles). The Great Australian Desert is the next largest desert. The Arabian Desert, Iranian Desert, Thar Desert, Kalahari Desert, and Namib Desert are among the other hot deserts

 

•    The hot deserts are found along the Horse Latitudes or Sub-Tropical High Pressure Belts, where the air is descending, making it difficult for precipitation to form. 

 

•    Rain-bearing Trade Winds blow off-shore, while on-shore Westerlies blow beyond the desert's boundaries. Whatever winds reach the deserts, they blow from cooler to warmer regions, lowering relative humidity and preventing condensation. In the endless blue sky, there are hardly any clouds. 

 

•    The relative humidity levels are extremely low, ranging from 60% in coastal areas to less than 30% in the desert interiors. Every drop of moisture evaporates in such conditions, and deserts become permanent drought zones. 

 

•    Precipitation is in short supply and notoriously unreliable. The presence of cold currents on the western coasts causes mists and fogs by chilling the oncoming air. Contact with the hot land warms the air, and little rain falls as a result. The cold Peruvian Current's desiccating effect along the Chilean coast is so strong that the Atacama Desert receives only 1.3 cm of annual rainfall.

 

•    Tides are cyclic deformations of an astronomical body caused by gravitational forces exerted by other astronomical bodies. The most well-known are the periodic variations in sea level on Earth that correspond to changes in the Moon's and Sun's relative positions. 

 

•    Forced waves, partially running waves, and partially standing waves can all be described as tides. They are characterized by vertical movements of the sea surface (high tide water [HTW] and low tide water [LTW]; (HTW-LTW=Tidal Range)) and alternating horizontal movements of the water, referred to as tidal currents. The terms ebb and flow are used to describe rising and falling tides, respectively.

 

•    The moon's gravitational pull, to a large extent, and the sun's gravitational pull, to a lesser extent, are the primary causes of tides. The centrifugal force, which acts to counterbalance gravity, is another factor to consider. 

 

•    The two major tidal bulges on the earth are caused by a combination of gravitational pull and centrifugal force. A tidal bulge occurs on the side of the earth facing the moon, while the centrifugal force causes a tidal bulge on the opposite side, despite the fact that the moon's gravitational attraction is less as it is farther away.

 

•    The difference between these two forces, namely the moon's gravitational attraction and the centrifugal force, is known as the "tide-generating" force. 

 

•    The moon's pull, or attractive force, is greater than the centrifugal force on the earth's surface closest to the moon, resulting in a net force causing a bulge towards the moon. 

 

•    The attractive force is weaker on the opposite side of the earth, and the centrifugal force is stronger as you get further away from the moon. As a result, there is a net force directed away from the moon. It causes the moon's second bulge to form. 

 

•    The horizontal tide generating forces are more important than the vertical forces in generating tidal bulges on the earth's surface. On wide continental shelves, tidal bulges have a higher height. The mid-oceanic islands experience low tidal bulges when tidal bulges hit them. 

 

•    The intensity of tides can be amplified by the shape of bays and estuaries along a coastline. Tidal magnitudes are dramatically altered by funnel-shaped bays. Tidal currents are formed when the tide is channeled between islands or into bays and estuaries.

 

Tides vary in frequency, direction, and movement from one location to another, as well as over time. Tides can be classified into different types based on how often they occur in a day or 24 hours, or on their height. 

 

1.    Frequency-based Tides: Semi-diurnal tides are the most common tidal pattern, with two high and two low tides per day. The height of successive high or low tides is approximately the same.

 

•    Each day has only one high tide and one low tide due to diurnal tides. The heights of the successive high and low tides are roughly equal.

 

2.    Mixed tides are tidal ebbs and flows that have varying heights. These tides are most common along the west coast of North America and on many Pacific Ocean islands. 

 

3.    Tides based on the positions of the Sun, Moon, and Earth The height of rising water (high tide) varies significantly depending on the relative positions of the sun and moon to the earth. This category includes both spring and neap tides.

 

4.    Tide height is directly related to the position of the sun and moon in relation to the earth during spring tides. The height of the tide will be higher when the sun, moon, and earth are all in a straight line. These are known as spring tides, and they occur twice a month, once during the full moon and once during the new moon.

 

5.    Neap tides: Between spring and neap tides, there is usually a seven-day interval. The sun and moon are at right angles to each other at this time, and their forces tend to balance each other out. Although the Moon's attraction is more than twice as strong as the sun's, the counteracting force of the sun's gravitational pull weakens it.

 

•    Unusually high and low tides occur once a month, when the moon's orbit is closest to the earth (perigee). The tidal range is wider than usual at this time. The moon's gravitational force is limited two weeks later, when it is farthest from Earth (apogee), and the tidal ranges are less than their average heights.

 

•    Tidal ranges are much greater when the earth is closest to the sun (perihelion), around the 3rd of January each year, with unusually high and low tides. Tidal ranges are much lower than average around the 4th of July each year, when the earth is farthest from the sun (aphelion). 

 

•    The ebb is the period of time between high and low tides when the water level is falling. The flow or flood refers to the period of time between low and high tide when the tide is rising.