Marine Chapter 4: Water Wind Currents

Properties of Water

• Water acts as a solvent, allowing it to mingle with various substances.
• The maximum density of pure water occurs at 4 degrees Celsius; below this temperature, water freezes.
• The density of air increases with increasing moisture, affecting atmospheric conditions.

Heat Transfer

• Most heat transfer from the atmosphere to the Earth occurs through absorption by the lithosphere.
• If Earth absorbed more solar energy than it radiated, temperatures would rise continuously.

Water Density Factors

• Water density is primarily controlled by salinity and temperature, influencing aquatic ecosystems.

Thermocline and Circulation

• The thermocline is a layer in the ocean where temperature changes rapidly, distinguishing water layers.
• Upwelling is the process where nutrient-rich water rises to replace surface water, enhancing marine productivity.

Wind Patterns and Currents

• The Coriolis effect causes the apparent deflection of air paths due to Earth's rotation, influencing weather patterns.
• Wind designations are made based on the direction from which they originate.
• Trade winds blow toward the equator from 0 to 30 degrees latitude, while polar easterlies flow toward the equator from 60 to 90 degrees latitude.

Oceanic Gyres

• There are five major ocean gyres, each corresponding to a specific ocean basin, with the North Atlantic gyre typically flowing clockwise.
• Gyres consist of currents divided into various categories, excluding the Ekman spiral.

Currents and Convection

• Primary energy sources for surface ocean currents include wind.
• Convection cells in the atmosphere arise from warm air rising and cool air flowing in to replace it, creating circular wind patterns.

Salinity Variations

• Ocean water near deserts tends to have higher salinity compared to average ocean salinity due to increased evaporation rates.

Ocean Composition

• Approximately 96.5% of ocean water is pure water, emphasizing the concentration of dissolved salts and nutrients in the remaining portion.

Additional Current Patterns

• Transverse currents flow from west to east, and eastern-boundary currents flow from north to south toward the equator.
• Downwelling refers to the process of surface water sinking into deeper layers, affecting nutrient distribution and marine life.

Meeting Regions

• The doldrums are where the northeast and southeast trade winds converge, creating areas of low winds and instability.

Uneven Solar Heating

• The sun heats the Earth unevenly due to its spherical shape, axial tilt, and elliptical orbit, influencing climatic zones and weather patterns.

Deep Circulation

• Deep ocean currents result from the mixing of water masses with different densities, driven by temperature and salinity variations.