Mechanism to replenish waters in the ”deep sea‘. Sinking of surface waters is a very important Waters cool and become dense enough to sink thousands of meters. This situation found at high latitudes near Occurs where there is cold air to cool water at surface. e.g., like submerging a rubber duck in bathtub (you supply energy). Situation it takes energy input (usually from the wind) to 'push' In this situation the water column is ‘stable‘. Īt surface is lower than below, the water will not sink. This situation the water column is ‘unstable’. If density of water at surface is higher thanīelow, the water will sink to a level of its own density. Seawater determines its tendency to move vertically. To form ice on a lake (freshwater) than on a bay (seawater). F reshwaterįreezing point versus salinity explains why it is easier Salinity of seawater also affects it‘s freezing point temperature. The salinity decreases from the surface ocean to deep waters is very small,įrom about 36 g/L ( ppt) at the surface to 35 g/L ( ppt) in the deep water, thus there is a very small density decrease with depth given a constant temperature. This resulting seawater is denser thanįreshwater because of added mass of dissolved salt. Of salt to one liter (1 kg) of this freshwater (35 grams per 1000 grams). Make seawater, start with freshwater and add 35 grams Thousand ( ppt), thus typical seawater is between 33 Oceanographers measure salinity in parts per The extremes of salinity can range from 28 to 40 g/L. Much salt is in seawater? Typically seawater contains between 33 to 37 grams of Polar ocean (somewhat uniformly cold at the surface and at increasing depths). (warm at the surface and colder with increasing depth) and least in the cold It is greatest in the warm tropical ocean The steepness of theĭepth gradient in temperature depends on location.

Temperature with depth is called the temperature gradient. Where temperature decrease is greatest with depth is called the thermocline. Of the ocean is warm at the surface and colder at increasing depths. Temperature range for air, which varies from -60☌ to +60☌. This is not necessarily the situation in the polarįor ocean water ranges from ~ -2☌ to +40☌, which is much smaller than the Will take energy to mix the ocean vertically. This means that in most regions the ocean is stable, that is, it Salinity decrease and makes the deeper water more dense Greatest role in determining the density of a sample of water.ĭensity due to the decreasing temperature with depth dominates over the

Theĭensity increase with depth caused by the temperature decrease plays the Of about a 20☌ temperature decrease from the surface to bottom of ocean. Increase upon cooling from 20° to 0☌? Seawater density increases from 1.0240 g/ cm 3 at 20☌ to 1.0273 g/ cm 3 at 0☌ at aĬonstant salinity. Molecules in smaller volume results in a higher density. (because the molecules are vibrating less at lower temperatures) and take up As water cools, H 2O molecules pack more closely together Why do you think the mass of water is defined at a specificįrom about 1.020 to 1.070 g/ cm 3 The changes in density are caused mainly by variations inĬauses density increase - pressure increases with depth due to the mass of Per unit volume and has units of grams per cubic centimeter (g / cm 3), kilograms per liter (kg/ L) or kilogramsĭensity of fresh water at 4° C is 1.0000 g/ cm 3

Density of water gcm3