Water and Ocean Structure. WORLDS WATER SOURCES:. Learning Objectives 1. Understand the nature of the water molecule and its unique properties (polarity, density and thermal properties) and how these are altered by the presence of salt in solution.
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1. Understand the nature of the water molecule and its unique properties (polarity, density and thermal properties) and how these are altered by the presence of salt in solution.
2. Know the types of materials that are dissolved in sea water, their importance and how they vary with time.
3. Explain variations in salinity, temperature, and pressure within the sea and how they alter the chemical and physical properties of the ocean.
Seawater density depends on temperature, salinity and pressure! Therefore, it increases with > salt content at const. temp;
high density in cold, salty waters –why is this important?
(“the universal solvent”)
Did oceans’ salinity increase over time?
35 g of salt in 1000 g of seawater
Same as pycnocline (density) and thermocline;
medium salinity in blue (35 o/oo), and low salinity (34 o/oo) in
purple. Salinity is rather stable but areas in the North Atlantic,
South Atlantic, South Pacific, Indian Ocean, Arabian Sea, Red Sea,
and Mediterranean Sea tend to be a little high (green). Areas near
Antarctica, the Arctic Ocean, Southeast Asia, and the West Coast
of North and Central America tend to be a little low (purple).
Carbonate buffering system keeps the pH of seawater constant = 8.1
What is temperature?
It is a direct measure of the average kinetic energy of atoms and molecules that make up substance. Temp. changes when heat energy is added to or removed from a substance.
It is measured in (Celsius, Kelvin, and Fahrenheit).
What is temperature?
(the energy of moving molecules = kinetic energy)
1) Represents the transfer of energy from high to low temperature. Therefore, heat has units of Energy (1 calorie, calor = heat; the amount of heat required to raise the temp. of 1 gram of water by 1 C°);
2) An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy.
Heat Capacity – the amount of heat required to raise the temp. of 1 g of any substance by 1 °C;
– Water has one of the highest heat capacities known, which makes water excellent heat transfer material; and
– therefore, allows ocean currents to moderate global climate!
Evaporation from lakes, oceans, rivers, etc. occurs for temperatures lower than 100 oC
But it requires more energy to do so
Atmospheric transport of surplus heat from low latitudes into heat deficient high latitudes areas: