Hydrologic Cycle, Surface Water, and Climate Dynamics

Reservoirs

Storage locations for water, largest to smallest: Oceans (~97%), Glaciers/ice caps (~2%), Groundwater (~0.6%), Surface water (rivers, lakes) (~0.01%), Atmosphere (<0.001%), Biosphere (tiny fraction).

Fluxes

Movement of water through processes such as evaporation, condensation, precipitation, infiltration, runoff, transpiration, and sublimation.

Evaporation

The process where liquid water turns into vapor, requiring energy from the Sun and absorbing latent heat.

Condensation

The process where water vapor turns into liquid, releasing latent heat to the atmosphere.

Precipitation

The process where water falls from the atmosphere to the surface.

Infiltration

The process where water soaks into the ground.

Runoff

The process where water flows over land into rivers and eventually to the ocean.

Transpiration

The process where plants release water vapor through their leaves.

Sublimation

The process where solid water (snow/ice) turns directly into vapor.

Watershed

The area of land where all water drains to a common outlet such as a river, lake, or ocean.

Stream properties downstream

Downstream, discharge, channel width, and velocity usually increase, while gradient and sediment size decrease.

Meanders

Curves in a river where water flows faster on the outside bend (causing erosion) and slower on the inside bend (leading to deposition and point bars).

Unconfined aquifer

An aquifer that is open to the surface and can be easily recharged.

Confined aquifer

An aquifer that is trapped between impermeable layers and is under pressure.

Recharge

The process where water enters an aquifer.

Discharge

The process where water exits an aquifer, occurring through springs, wells, or baseflow.

Overdrafting

A condition where discharge exceeds recharge, causing the water table to drop.

Dams/reservoirs

Human modifications that store water and generate hydroelectricity but can disrupt ecosystems.

Irrigation

The artificial application of water to support agriculture, which can lead to salinization.

Groundwater pumping

The extraction of groundwater, which can lead to depletion.

Urbanization

The process of increasing urban areas, which raises runoff and reduces infiltration.

Water threats

Challenges to water quality and quantity, including pollution, eutrophication, droughts, overuse, and climate change.

Desalination

A process used to convert seawater to freshwater, implemented in places like Saudi Arabia and California.

Inter-basin transfers

The movement of water from one river basin to another, exemplified by the Colorado River Aqueduct.

Conflicts

Disputes over water resources, such as those involving the Nile River (Egypt vs. Ethiopia) and the Colorado River (U.S. states vs. Mexico).

Socioeconomic challenges

Issues faced by low-income areas, including lack of infrastructure and waterborne diseases, contrasted with high-income areas that experience high consumption and groundwater depletion.

Salinity

Concentration of dissolved salts in water, approximately 35‰ in ocean water.

Density

Mass per unit volume of water, influenced by salinity and temperature.

Buffering capacity

Ability of water to resist changes in pH due to dissolved salts.

Heat capacity

The ability of water to absorb and store heat, moderating climate.

Wind-driven surface currents

Ocean currents generated by frictional drag from prevailing winds.

Coriolis effect

Deflection of moving objects due to Earth's rotation; right in N. Hemisphere, left in S. Hemisphere.

Ekman transport

Surface water moves 45° to wind direction, causing deeper layers to deflect further, resulting in a net movement of 90° to the wind.

Upwelling

The process where deep, cold water rises to the surface, often rich in nutrients.

Downwelling

The process where surface water sinks, often associated with warmer, less dense water.

Surface circulation

Ocean circulation driven by wind, occurring over months to years.

Deep circulation

Thermohaline circulation driven by density differences, occurring over centuries to millennia.

Bottom water formation

Cold, salty, dense water that forms near the poles, such as Antarctic Bottom Water.

Major gases in atmosphere

N₂ (~78%), O₂ (~21%), Ar (~0.9%), CO₂ (~0.04%), with variable water vapor and aerosols.

Relative humidity (RH)

Calculated as RH = (actual vapor pressure / saturation vapor pressure) × 100%.

Adiabatic cooling

Cooling of air as it rises and expands.

Troposphere

Lowest layer of the atmosphere where temperature decreases with height and weather occurs.

Stratosphere

Layer of the atmosphere where temperature increases with height due to ozone.

Mesosphere

Layer of the atmosphere where temperature decreases with height.

Thermosphere

Layer of the atmosphere where temperature increases with height; contains auroras.

Convection cells

Circulation patterns in the atmosphere where warm air rises and cool air sinks.

Three-cell model

Atmospheric circulation model consisting of Hadley Cell, Ferrel Cell, and Polar Cell.

Weather

Short-term atmospheric conditions.

Climate

Long-term averages of weather conditions.

ENSO

El Niño/La Niña phenomenon affecting rainfall, temperature, and fisheries.

Monsoons

Seasonal wind reversals caused by differential heating.

Ocean-climate link

The ocean's role in storing and redistributing heat, regulating global climate.