Glossary
water cycle
The water cycle is the endless movement of water between the ocean, the air and the land — evaporation, condensation, precipitation, and runoff or infiltration back to the sea.
The water cycle is the continuous circulation of Earth's water among the oceans, the atmosphere and the land. Heat from the Sun evaporates water from lakes, rivers and the sea, and plants add more through transpiration, so water enters the air as vapor. As that vapor rises and cools it condenses onto tiny particles to form clouds. When the droplets grow heavy enough they fall as precipitation — rain, snow, sleet or hail — and the water then runs off across the surface into streams and rivers or infiltrates down into the soil and becomes groundwater, on its way back to the sea.
The Sun is the engine of the whole cycle, and it is the most common one-step answer a question here wants. Gravity does the other half, pulling the precipitation down and the runoff seaward.
Keep the vocabulary pairs clean, because the questions turn on telling them apart. Evaporation and transpiration put water into the air; condensation makes clouds; precipitation brings it back down; runoff travels over the ground while infiltration soaks in. The water itself is not used up — it changes state and place, which is why every stage of the cycle is a physical change rather than a chemical one.
Taught in
Related terms
- states of matter — The states of matter are solid, liquid and gas: a solid holds its own shape and volume, a liquid holds its volume but takes the shape of its container, and a gas holds neither.
- convection — Convection moves heat by moving the heated material itself: warm fluid or air expands, rises because it is less dense, cools, and sinks, setting up a circulating current.
Source: Official ASVAB — subtest descriptions (what each subtest asks) and the CAT-ASVAB scored-question counts (accessed 2026-09)