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All 35 Flashcards — The hydrological cycle
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Question
What is the hydrological cycle?
Answer
The continuous movement of water between atmosphere, land, and oceans through evaporation, condensation, precipitation, infiltration and runoff.
💡 Hint
One-sentence definition.
Question
State the system type of the global hydrological cycle for matter and for energy.
Answer
Matter: closed (same water recycled). Energy: open (solar energy enters, heat leaves).
💡 Hint
Closed vs open.
Question
Define evapotranspiration.
Answer
Evapotranspiration is the combined total water loss from an area through both evaporation and transpiration.
💡 Hint
Evaporation + transpiration.
Question
Why does evaporation cause cooling?
Answer
Evaporation requires energy to break bonds between water molecules. This energy is absorbed from the surroundings, so the surroundings lose energy and cool down.
💡 Hint
Break bonds → energy from surroundings.
Question
What is a phase change in the water cycle?
Answer
A change of state of water, such as liquid to gas (evaporation) or gas to liquid (condensation).
💡 Hint
State change.
Question
Why does condensation cause warming?
Answer
When water vapour condenses (gas to liquid), molecular bonds form and energy is released to the surroundings. The surroundings gain energy and warm up.
💡 Hint
Form bonds → energy out.
Question
Define evaporation in the water cycle.
Answer
Evaporation is liquid water changing to water vapour from non-living surfaces such as oceans, lakes, rivers or wet soil, absorbing latent heat.
💡 Hint
Non-living surfaces.
Question
Define transpiration in the water cycle.
Answer
Transpiration is the loss of water vapour from living plants through stomata in leaves, absorbing latent heat.
💡 Hint
Plants + stomata.
Question
Give one example where condensation releases heat.
Answer
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.
💡 Hint
Condensing steam releases heat.
Question
Define latent heat.
Answer
Energy absorbed or released during a phase change without a change in temperature.
💡 Hint
Hidden energy.
Question
Name three major stores of water on Earth.
Answer
Oceans, ice/glaciers, and groundwater (also rivers/lakes, atmosphere, living things).
💡 Hint
Stores = where water is held.
Question
Name three factors that increase evapotranspiration.
Answer
Higher temperature, lower humidity, and stronger wind increase evapotranspiration (also greater vegetation cover and higher water availability).
💡 Hint
Hot, dry, windy.
Question
Give two everyday examples of evaporative cooling.
Answer
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.
💡 Hint
Skin + evaporation.
Question
Define latent heat in one sentence.
Answer
Latent heat is the “hidden” energy absorbed or released during a phase change without changing temperature.
💡 Hint
Hidden energy.
Question
Explain (3 marks) condensation warming in exam style.
Answer
(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).
💡 Hint
3 steps.
Question
Name three flows in the hydrological cycle.
Answer
Evaporation, precipitation, and runoff (also transpiration, condensation, infiltration, percolation).
💡 Hint
Flows = how water moves.
Question
During evaporation, is latent heat absorbed or released?
Answer
Absorbed. Energy is required to break bonds as liquid water becomes water vapour.
💡 Hint
Breaking bonds needs energy in.
Question
Explain (3 marks) evaporative cooling in exam style.
Answer
(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).
💡 Hint
3 steps.
Question
What is the key difference between evaporation and transpiration?
Answer
Evaporation occurs from non-living surfaces, while transpiration occurs from living plants (via stomata).
💡 Hint
Non-living vs plants.
Question
How does humidity affect evapotranspiration?
Answer
Low humidity increases evapotranspiration because dry air can accept more water vapour, maintaining a strong diffusion gradient from surfaces and leaves.
💡 Hint
Dry air = more “room”.
Question
Complete the trio: evaporation, transpiration, evapotranspiration.
Answer
Evaporation = from non-living surfaces. Transpiration = from plants (stomata). Evapotranspiration = both combined total water loss.
💡 Hint
Non-living, plants, both.
Question
Why can forests cool local climate?
Answer
Trees transpire large amounts of water vapour. This transpiration absorbs latent heat from the surroundings, lowering local air temperature.
💡 Hint
Transpiration = cooling.
Question
Do evaporation and transpiration absorb or release latent heat?
Answer
Both absorb latent heat from the surroundings during the liquid to gas phase change, producing a cooling effect.
💡 Hint
Both cool.
Question
During condensation, is latent heat absorbed or released?
Answer
Released. Energy is transferred to the surroundings as bonds form when vapour becomes liquid.
💡 Hint
Forming bonds releases energy out.
Question
For 4 marks: outline how energy is transferred in the water cycle.
Answer
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.
💡 Hint
Solar → evap; latent heat in/out.
Question
Why does wind increase evapotranspiration?
Answer
Wind removes moist air from the surface/leaf boundary layer and replaces it with drier air, increasing evaporation and transpiration rates.
💡 Hint
Moves moist air away.
Question
In the global water cycle, is matter open or closed? What about energy?
Answer
Matter is closed (no net water enters or leaves Earth). Energy is open (solar energy enters and heat energy leaves).
💡 Hint
Closed for matter, open for energy.
Question
How does latent heat help redistribute energy globally?
Answer
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.
💡 Hint
Absorbed low, released high.
Question
Link deforestation to warming using latent heat.
Answer
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.
💡 Hint
Less ET → less cooling.
Question
Quick check: evaporation vs condensation energy change.
Answer
Evaporation absorbs latent heat; condensation releases latent heat.
💡 Hint
Absorb vs release.
Question
Which has higher evapotranspiration: a forest or a desert (same rainfall), and why?
Answer
A forest, because it has much more vegetation and leaf area (more stomata), so transpiration is far greater than in a desert.
💡 Hint
More leaves = more transpiration.
Question
Write a model exam sentence explaining evaporation vs transpiration.
Answer
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.
💡 Hint
One clear contrast + shared point.
Question
Why does temperature stay constant during a phase change?
Answer
Because energy is used to break or form molecular bonds rather than increasing or decreasing kinetic energy, so temperature does not change.
💡 Hint
Bonds, not temperature.
Question
What is the main energy driver of the hydrological cycle?
Answer
Solar energy, which powers evaporation and drives energy transfers through phase changes.
💡 Hint
Sun powers evaporation.
Question
In one sentence: evaporation vs condensation energy change.
Answer
Evaporation absorbs latent heat from the surroundings (cooling) whereas condensation releases latent heat to the surroundings (warming).
💡 Hint
Absorb vs release.
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Water systems
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