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Geography
The water cycle — A water droplet's journey
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A cutaway landscape showing surface water, air, clouds, soil and groundwater. Select a water store to follow a parcel of water, change conditions and observe the processes.
Purple marks a parcel of water. Real water vapor is invisible; shapes and timing are simplified.
Change one condition, then restart this scene to compare.
Water is in
Surface water
Liquid
The water is in the lake. Start to follow it as it evaporates.
Shows up to the 12 most recent transitions of the tracked parcel of water.
Press Play to follow water from the lake.
This is the path taken, not a sequence every droplet must follow.
Model notes
- This is a qualitative closed-system model using symbolic parcels of water. Sizes, amounts in each store and transition timing do not represent Earth's water distribution, liters, rainfall amounts or real travel times.
- The tracer represents a parcel of water, not a liquid droplet keeping its shape during evaporation. Water vapor is invisible; the cloud shown here contains tiny liquid droplets.
- Warming levels compare evaporation with other conditions held constant. “Cool enough” assumes moist air reaches condensation conditions and nuclei are present; it is not a fixed temperature for every humidity. More sunshine does not always mean more rain.
- Cloud droplets grow before falling. Waiting times and soil capacity are simplified for observation; they are not laws for rainfall timing, groundwater speed or all saturated soil stopping infiltration.
- Only some pathways in a landscape without ice or snow are shown. Plant transpiration, soil evaporation, rain over the sea, wind, energy, water extraction and pollution are outside this model. Natural water can take other paths and remain stored for a long time.