Ocean Weather and Thermodynamics

Study Notes

Ocean Weather and Forces

Surface winds create ocean eddies, influencing weather on various timescales.
Bathymetry, or sea-floor topography, plays a critical role in shaping ocean currents and eddies.
Ocean currents can become unstable, leading to the development of eddies.

Waves

Surface waves are generated by the friction between ocean water and surface winds.
Tsunamis are triggered by underwater seismic events, such as earthquakes, landslides, or volcanic eruptions.

Thermodynamics and Vapour Pressure

The tropical atmosphere is thermodynamically driven, necessitating moisture for weather phenomena.
Vapour pressure (e): the portion of pressure in air attributable to water vapour, indicating moisture content.
Saturated vapour pressure (eg): occurs when water vapour is in equilibrium with liquid water or ice; it increases exponentially with temperature.

Humidity Metrics

Relative humidity (H): the ratio of actual vapour pressure to saturated vapour pressure at a given temperature and pressure.
- Calculated as H = (vapour pressure / saturated vapour pressure) × 100%.
- When H exceeds 100%, condensation takes place.
Specific humidity (q): a measure of the mass of water vapour in a unit mass of moist air, expressed in g/kg or kg/kg.
- Formula: q = density of water vapour / density of moist air.

Dew-Point Temperature

The dew-point temperature is the temperature at which air becomes saturated if cooled under constant pressure, without changing vapour amount.
Cooling of air at constant specific humidity leads to condensation, as vapour pressure remains constant while saturated vapour pressure decreases with temperature.

Adiabatic Processes

Adiabatic ascent relates to rising air with no heat exchange; as air rises, its temperature decreases due to expansion.
The vapour pressure remains relatively stable during adiabatic ascent, but the saturated vapour pressure declines steeply with temperature.
The adiabatic lapse rate defines the temperature decline rate in a rising, expanding air parcel.

Description

Test your knowledge on the forces driving ocean weather, including surface winds, bathymetry, and currents. Also, explore the concepts of thermodynamics in the tropical atmosphere, including vapour pressure and its significance.