Oceanography Exam 2: Water, Currents, Waves, and Climate

Covalent Bonds

Connects the two hydrogen atoms and one oxygen atom in the water molecule.

Polarity

A property of the water molecule, which has a 105-degree angle.

Hydrogen Bonds

Weaker than covalent bonds, but strong enough to result in high water surface tension, high solubility, unusual thermal properties, and unusual density.

Surface Tension (Cohesion)

A property of water resulting from hydrogen bonding.

Solubility

High solubility of chemical compounds in water is a result of hydrogen bonding.

Unusual Density

A characteristic property of water resulting from hydrogen bonding.

Three states of water

Solid, liquid, and gas.

Heat

The measure of the total amount of kinetic energy, measured in calories.

Temperature

A measure of the average kinetic energy of the atoms and molecules in a substance, measured in degrees (°F, °C, K).

Sublimation

The process where ice changes directly to a gas.

Latent heat of fusion

The heat necessary to change the state of water between solid and liquid.

Latent heat of vaporization

The heat needed for a change between the liquid and vapor (gas) states.

Specific heat of a material

The ability of a substance to give up or take in a given amount of heat and undergo large or small changes in temperature.

Heat capacity of a material

The quantity of heat required to produce a unit change of temperature in the material.

Global Thermostatic Effects

Water moderates Earth's climate and influences day/night temperature ranges.

Desert Temperature Range

Deserts have a large range of temperatures from day to night because they are so dry.

Pure Water Density vs. Temperature

Density increases with decreasing temperature down to 3.98°C, and then density decreases with decreasing temperature from 3.98°C to 0°C. Density also decreases at the phase transition from liquid to solid.

Open-ocean salinity

Typically 33-38 o/oo (parts per thousand).

Brackish water

Conditions created in coastal areas when an influx of freshwater lowers salinity.

Hypersaline

Conditions created in coastal areas when a greater rate of evaporation raises salinity.

Thermocline

The layer in the ocean where temperature changes rapidly with depth.

Halocline

The layer in the ocean where salinity changes rapidly with depth.

Pycnocline

The layer in the ocean where density changes rapidly with depth.

Surface currents

Wind-driven and primarily characterized by horizontal motion.

Deep currents (Thermohaline)

Driven by differences in density caused by differences in temperature and salinity, characterized by vertical and horizontal motions.

Coriolis Effect

The apparent deflection of moving air relative to Earth's surface, resulting from the variation in Earth's speed of angular rotation with latitude.

Surface Current Speed

About 1/100 of the wind speed 10 m above the sea surface.

Sverdrup (Sv)

A unit of current volume transport equal to 1,000,000 m³/s.

Western Intensification

Phenomenon where currents on the western sides of ocean basins (Western Boundary Currents) tend to be fast, narrow, and deep, moving warm equatorial surface water to higher latitudes.

North Atlantic Gyre Currents

Includes the North Equatorial Current, Gulf Stream (Western boundary current), North Atlantic (Northern boundary), and Canary (Eastern boundary current).

Sargasso Sea

Part of the gyre system known for its unique biology, specifically Sargassum.

Plastic Pollution in Gyres

Floating plastics photodegrade and break into smaller pieces, increasing the number of marine plastic particles; regions like the Eastern Pacific Garbage Patch accumulate this trash.

Coastal Upwelling (NW Coast, Summer)

Occurs in North America's NW coast during summer due to northerly winds.

Coastal Downwelling (NW Coast, Winter)

Occurs in North America's NW coast during winter due to southerly winds.

High Pressure

Associated with descending air, resulting in clear skies and low precipitation.

Low Pressure

Associated with ascending air, resulting in clouds and increased precipitation.

Global Circulation Cells

Three major convection cells associated with Trade winds, Westerlies, and Polar easterlies.

Thermohaline Circulation

Deep ocean circulation driven by temperature and density differences in water. This circulation accounts for 90% of all ocean water and has slow velocity.

Thermohaline Origin

Originates in the high-latitude surface ocean when cooled, dense surface water sinks.

Crest

The highest point of a wave.

Trough

The lowest point of a wave.

Wavelength (L)

The horizontal distance between two consecutive crests or troughs.

Wave Height (H)

The vertical distance between the crest and the trough.

Wave Period (T)

The time required for one full wavelength to pass a fixed point.

Wave Frequency (f)

The inverse of the wave period.

Wave Steepness (S)

The ratio of wave height (H) to wavelength (L).

Circular Orbital Motion

The movement pattern of water particles in a wave. The particle motion decreases with depth.

Wave Base

The depth (D) below which water particle motion is negligible, defined as L / 2 (half the wavelength).

Shallow-water waves

Waves that travel in water depths less than half their wavelength.

Deep-water wave becomes Shallow-water wave

Wave speed decreases, wavelength decreases, wave height increases, and wave steepness increases.

Wave Breaking

Occurs when the wave steepness (height/wavelength) exceeds 1/7.

Plungers (a)

Breaking waves that lose energy more quickly and form on narrow, steep beach slopes.

Spillers (b)

Breaking waves that are more common and form over wide, flat beach slopes.

Wind Speed (Wave Growth)

Faster wind results in greater surface drag, transferring more energy to the sea surface, thus increasing wave height.

Wind Duration (Wave Growth)

Wind energy is 'cumulative'—the longer the wind blows, the larger the waves grow.

Fetch (Wave Growth)

The distance the wind blows over the water; longer fetch results in greater wave energy and height.

Rip Currents

A fast, concentrated current where water accumulated in the surf zone flows seaward (return flow).

Longshore Transport

The overall movement of sediment along the coast.

Beach drift

Sediment moves in a zigzag pattern along the beach face.

Longshore current

A current located in the surf zone that flows parallel to the shore and moves substantially more sediment than beach drift.

Groins

Hard stabilization structure: Barriers built at a right angle to the beach, designed to trap sand.

Breakwaters

Hard stabilization structure: Barriers built offshore and parallel to the shore to protect boats from breaking waves.

Seawalls

Hard stabilization structure: Armors the coast against breaking waves, often noted as not effective.

Jetties

Hard stabilization structure listed alongside groins, breakwaters, and seawalls.

Beach Restoration

Alternatives to hard stabilization, including beach nourishment (adding sand to the beach system) and relocating buildings away from the beach.