Water systems

Evaporation requires energy to break bonds between water molecules. This energy is absorbed from the surroundings, so the surroundings lose energy and cool down.

Matter: closed (same water recycled). Energy: open (solar energy enters, heat leaves).

Evaporation is liquid water changing to water vapour from non-living surfaces such as oceans, lakes, rivers or wet soil, absorbing latent heat.

When water vapour condenses (gas to liquid), molecular bonds form and energy is released to the surroundings. The surroundings gain energy and warm up.

A change of state of water, such as liquid to gas (evaporation) or gas to liquid (condensation).

The continuous movement of water between atmosphere, land, and oceans through evaporation, condensation, precipitation, infiltration and runoff.

Evapotranspiration is the combined total water loss from an area through both evaporation and transpiration.

Oceans, ice/glaciers, and groundwater (also rivers/lakes, atmosphere, living things).

Latent heat is the “hidden” energy absorbed or released during a phase change without changing temperature.

Higher temperature, lower humidity, and stronger wind increase evapotranspiration (also greater vegetation cover and higher water availability).

Transpiration is the loss of water vapour from living plants through stomata in leaves, absorbing latent heat.

Examples include storms/hurricanes intensifying as condensation releases latent heat, a warm bathroom after a hot shower as steam condenses, or steam burns being severe when steam condenses on skin.

Examples include sweating cooling the body, feeling cold after swimming as water evaporates from skin, wet clothes making you feel colder, or a wet cloth cooling a fever.

Energy absorbed or released during a phase change without a change in temperature.

Evaporation, precipitation, and runoff (also transpiration, condensation, infiltration, percolation).

Evaporation occurs from non-living surfaces, while transpiration occurs from living plants (via stomata).

Absorbed. Energy is required to break bonds as liquid water becomes water vapour.

Evaporation = from non-living surfaces. Transpiration = from plants (stomata). Evapotranspiration = both combined total water loss.

Low humidity increases evapotranspiration because dry air can accept more water vapour, maintaining a strong diffusion gradient from surfaces and leaves.

(1) Condensation releases energy when molecular bonds form. (2) This energy is transferred to the surroundings. (3) The surroundings gain energy so temperature increases (warming).

(1) Evaporation requires energy to break molecular bonds. (2) This energy is absorbed from the surroundings. (3) The surroundings lose energy so temperature decreases (cooling).

Energy is absorbed at Earth’s surface during evaporation (often in warm regions) and released higher in the atmosphere during condensation, transferring heat and helping move energy around the planet.

Matter is closed (no net water enters or leaves Earth). Energy is open (solar energy enters and heat energy leaves).

Released. Energy is transferred to the surroundings as bonds form when vapour becomes liquid.

Trees transpire large amounts of water vapour. This transpiration absorbs latent heat from the surroundings, lowering local air temperature.

Both absorb latent heat from the surroundings during the liquid to gas phase change, producing a cooling effect.

Wind removes moist air from the surface/leaf boundary layer and replaces it with drier air, increasing evaporation and transpiration rates.

Solar energy drives evaporation. Latent heat is absorbed during evaporation (cooling). Latent heat is released during condensation (warming). This transfers and redistributes heat within the atmosphere.

Deforestation reduces transpiration and evaporation from vegetation. With less latent heat absorption, less energy is taken from the surroundings, so local cooling decreases and temperatures rise.

Evaporation absorbs latent heat; condensation releases latent heat.

A forest, because it has much more vegetation and leaf area (more stomata), so transpiration is far greater than in a desert.

Solar energy, which powers evaporation and drives energy transfers through phase changes.

Evaporation absorbs latent heat from the surroundings (cooling) whereas condensation releases latent heat to the surroundings (warming).

Because energy is used to break or form molecular bonds rather than increasing or decreasing kinetic energy, so temperature does not change.

Evaporation is the loss of water vapour from non-living surfaces such as oceans and lakes, whereas transpiration is the loss of water vapour from plants through stomata; both are driven by solar energy and absorb latent heat.

About 97% is in oceans (saltwater) and about 3% is freshwater.

Because water absorbs, stores, and redistributes heat, reducing temperature extremes and helping stabilise climate.

An aquifer is an underground rock layer that stores water in pores and cracks.

Water can absorb a lot of heat energy with only a small temperature rise, so oceans act as heat sinks that buffer daily and seasonal temperature changes.

Evaporation absorbs latent heat (cooling) and condensation releases latent heat (warming), moving energy around the atmosphere.

Residence time is how long water remains in a store before moving to another part of the system.

Infiltration is water soaking into the soil surface. Percolation is water moving downward through soil/rock to groundwater or aquifers.

Ocean currents redistribute heat from the tropics to higher latitudes; for example, warm currents can raise temperatures in nearby coastal regions.

If extraction exceeds recharge, aquifers can take centuries to refill, so water can run out within human lifetimes.

Ice and snow have high albedo so they reflect more solar radiation (cooling). When ice melts, darker water absorbs more radiation (warming).

Catchment (drainage basin) is the AREA where water drains to one river. Watershed is the BOUNDARY line between basins.

A drainage basin is an area of land where all precipitation drains into a single river system, bounded by a watershed.

A watershed is the boundary line (usually high ground like hills/ridges) that separates two drainage basins.

Precipitation is the main water input and solar energy drives processes like evapotranspiration.

River discharge to the sea/lake and evapotranspiration are key outputs (also abstraction by humans).

Examples include the source, tributaries, confluence, main channel, floodplain, and the mouth.

A confluence is the point where two rivers or streams meet.

At the local scale a drainage basin is an open system: water enters as precipitation and leaves via evapotranspiration and runoff/discharge.

Water, sediments, and pollutants move through tributaries into the main river, so land use upstream can change flooding, water quality, and ecosystems downstream.

Because activities anywhere in the basin can change flow, sediment, and pollution, affecting ecosystems and people downstream.

High specific heat capacity, latent heat transfer (evaporation/condensation), ocean currents, water vapour greenhouse effect, and albedo effects of ice/snow.

High specific heat capacity: water absorbs lots of heat with little temperature change, so oceans buffer climate.

Warming increases evaporation, raising atmospheric water vapour, which strengthens the greenhouse effect and causes further warming.

Evaporation absorbs heat (cooling). Condensation releases heat (warming).

They move heat from the tropics toward the poles and return cooler water toward lower latitudes, redistributing energy.

Melting reduces surface albedo, exposing darker water/land that absorbs more solar radiation, increasing warming (ice–albedo feedback).

Oceans absorb CO2 from the atmosphere, reducing atmospheric warming, but increased CO2 dissolving can contribute to ocean acidification.

It is a greenhouse gas that traps heat, and it can increase as temperatures rise, strengthening warming feedbacks.

Give several distinct mechanisms as separate points (one per sentence), such as specific heat capacity, latent heat transfer, currents, greenhouse effect, and albedo.

Ice and snow reflect solar radiation due to high albedo, producing a cooling effect.