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Andrew Bullen and Colin Bursey

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` How temperature affects water properties

` Stratification and thermoclines

` Surface temp patterns

` How currents and temperature interplay` References

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` Water can occupy either of its three physical

states depending mainly on its temperature.

Solid (Ice)

Liquid (Water as we generally think of it)

Gas (Steam orWater vapour)

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The temperature and density of water are inversely

proportional. This means that as the temperature

of the water decreases the density of the water

increases correspondingly.As the water molecules lose thermal energy they

become less excited and more tightly packed. This

increases density.

Fresh Water is most dense at 4C. Solutes changedensity and salt water is thus different.

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The ability of water to hold dissolved substances

decreases as its temperature increases. These

properties are also inversely proportional.

This decreased tolerance of solutes is due to

greater spacing of the water molecules as they

gain kinetic energy. The molecular interactions

between water and the solute are dramaticallyweakened.

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Decreasing Temperature Increasing Temperature

` Decrease density` Decrease solubility

` Increase density` Increase solubility

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` Changes in density caused by temperature

differences can cause sharp divisions between

layers of water.

` The different layers are separated by bordersknown as thermoclines.

` Denser cold water forms the bottom layer while

warmer water floats on top of the cold to form the

upper layer. There may be no layers at all ormultiple layers depending on local conditions.

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Image courtesy of Water on the Web

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` Latitude has a strong correlation to surface

temperatures due to varying insolation at differing

latitudes.

` The angle of the sun to the earth and its tiltedrotational axis cause solar energy input to vary

seasonally however areas closer to the equator

generally receive more solar energy then areas

closer to the poles.` Therefore surface temperatures are generally

higher at lower latitudes.

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` Tropics and subtropics often >25C

` Polar regions often near or < 0C

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` When a deep water cold current meets a land

mass (sea mount, continent, ect.) the cold water is

forced upwards. This upwelling is often nutrient

rich and provides the food base for many strongfisheries

` As warm surface currents head north they cool

and the water sinks. This is known as downwelling.

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Pinet, Paul R. (2009) Invitation to Oceanography, 5th

edition. Jones and Bartlett, Sudbury, MA.

Castro, Peter, and Huber Michael E. (2003) Marine

Biology, 4th edition. Mcgraw Hill, New York, NY