Water Cycle and Mass Balance Practice Flashcards

Vocabulary flashcards covering the components, characteristics of major stores, mass balance equations, and transfer processes of the global water cycle.

Inputs

Water entering a system, including examples such as precipitation (rain, snow, hail) and condensation from the atmosphere.

Outputs

Water leaving a system, such as evaporation, transpiration, river discharge to oceans, and sublimation.

Sublimation

The process of water moving from a solid state (ice) directly to a gaseous state (vapour).

Stores

Places where water is held, such as oceans, the atmosphere, cryosphere, lakes, rivers, soil moisture, groundwater, and vegetation.

Flows / Transfers

The movement of water between stores, which includes processes like infiltration, percolation, surface runoff, and throughflow.

Mass Balance

The concept that the change in storage is determined by the equation $Inputs - Outputs = \text{Change in storage}$.

Positive balance

A state where $Inputs > Outputs$, leading to increased stores, such as flooding or glacier growth.

Negative balance

A state where $Outputs > Inputs$, leading to shrinking stores, such as during a drought or the melting of ice sheets.

Oceans

The largest water store, containing approximately $9721$ of Earth's water, characterized by saline water and a residence time of around $3000\,years$.

Cryosphere

The largest freshwater store, comprising ice sheets (primarily in Antarctica and Greenland), glaciers, sea ice, and permafrost.

Atmosphere

A tiny water store accounting for approximately $0.001\%$ of water, held as vapour or clouds, with a rapid residence time of around $8-10\,days$.

Soil moisture

A temporary water store influenced by soil type, vegetation, precipitation, and temperature.

Groundwater

A large freshwater store held in aquifers and permeable rock, characterized by slow transfer rates and a water table.

Vegetation store

Water held in biomass or through interception, which is especially important in tropical rainforests.

Thermal expansion

A cause of rising sea levels where warmer ocean waters expand and occupy more volume.

Accumulation

The gain of ice and snow in a cryospheric system, such as through snowfall or refreezing.

Ablation

The loss of ice from a system through processes like melting, sublimation, and calving.

Glacier mass balance

The net change in a glacier's size calculated as $Accumulation - Ablation$.

Advection

The atmospheric process of moisture transfer by winds.

Stemflow

A flow process where intercepted water runs down the stems and trunks of plants to the ground.

Infiltration

A hillslope process involving the entry of water from the surface into the soil.

Percolation

The downward movement of water through soil or rock layers toward the groundwater store.