On a hot afternoon, water moves from oak leaves into the air as vapor. What process transfers the water?

Sunlight causes liquid water at the ocean surface to become water vapor. What process is occurring?

Water vapor cools high in the atmosphere and forms cloud droplets. What process formed the droplets?

Cloud droplets grow heavy and fall as rain over a watershed. What water-cycle process moves the water to the ground?

After rain, water enters the upper layer of soil rather than flowing across a lawn. What process is this?

Water already in soil moves downward through porous rock until it reaches an aquifer. What process is occurring?

On a cold, dry day, snow in the Rocky Mountains changes directly into water vapor without melting. What process occurred?

A forest loses water vapor from leaves while nearby wet soil also loses water vapor. What term includes both transfers?

Stormwater flows over a paved parking lot into a storm drain and then a river. What process transfers the water across the land?

Where is most of Earth's freshwater stored?

Which water-cycle reservoir holds about 97 percent of all the water on Earth?

A community obtains potable water by pumping a well that reaches a saturated layer of sand and rock. Which reservoir supplies the water?

Water vapor above a city is part of which water-cycle reservoir?

After a storm, water stays in the unsaturated layer above the water table, where plant roots can take it up. What reservoir is this?

Spring snowpack in a mountain watershed stores water temporarily before meltwater enters streams. Which reservoir contains that water?

Why can a river supply only a small fraction of Earth's total freshwater even though people use rivers heavily?

A meadow is replaced by an impervious shopping-center parking lot. How does this change the local water cycle during storms?

A watershed loses mature forest to intensive clearing. Which change is most likely during the following growing season?

Developers drain a wetland before building homes. What water-cycle service is reduced most directly?

A city installs rain gardens beside streets, using deep-rooted native plants and permeable soil. What change is expected after rainfall?

Irrigation wells withdraw groundwater from an aquifer faster than precipitation recharges it. What is the likely result?

A farmer replaces bare, compacted fields with perennial grass cover. During heavy rain, what change is most likely?

A housing development routes roof runoff through pipes directly to a stream instead of allowing it to soak into yards. Which process is reduced?

A city removes pavement and restores a floodplain beside a river. During storms, what is the most likely immediate effect?

A water molecule remains in the atmosphere for about 9 days but can remain in deep groundwater for thousands of years. What does this contrast describe?

A wetland holds stormwater and releases it gradually to a stream. Compared with a concrete drainage ditch, what happens to water's local residence time?

Why can contamination in a deep aquifer remain a concern for many years after the original spill is stopped?

A free-flowing stream is converted into a large reservoir behind a dam. How does the dam generally affect the average residence time of water at that site?

Reservoir A and Reservoir B each hold the same volume of water, but water flows out of A much faster. Which reservoir has the longer average residence time?

A lake stores 12 km³ of water and its average outflow is 3 km³ per year. What is its approximate residence time?