What is the significance of the water cycle

Plants take up groundwater either using it or releasing it to the atmosphere. The hydrologic cycle is important because it is how water reaches plants, animals and us! Besides providing people, animals and plants with water, it also moves things like nutrients, pathogens and sediment in and out of aquatic ecosystems. One of the ways that water moves through the cycle is through its ability to permeate, or soak, into the soil.

Runoff, and groundwater seepage, accumulate and are stored as freshwater in lakes. Not all runoff flows into rivers, though. Much of it soaks into the ground as infiltration. Some water infiltrates deep into the ground and replenishes aquifers saturated subsurface rock , which store huge amounts of freshwater for long periods of time. Some infiltration stays close to the land surface and can seep back into surface-water bodies and the ocean as groundwater discharge , and some groundwater finds openings in the land surface and emerges as freshwater springs.

Over time, though, all of this water keeps moving, some to reenter the ocean, where the water cycle "ends" For an estimated explanation of where Earth's water exists, look at the chart below. By now, you know that the water cycle describes the movement of Earth's water, so realize that the chart and table below represent the presence of Earth's water at a single point in time. If you check back in a thousand or million years, no doubt these numbers will be different!

Notice how of the world's total water supply of about million cubic miles 1, million cubic kilometers of water, over 96 percent is saline. And, of the total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Thus, rivers and lakes that supply surface water for human uses only constitute about 22, cubic miles 93, cubic kilometers , which is about 0.

One estimate of global water distribution Percents are rounded, so will not add to The air is full of water, even if you can't see it. Higher in the sky where it is colder than at the land surface, invisible water vapor condenses into tiny liquid water droplets—clouds. When the cloud droplets combine to form heavier cloud drops which can no longer "float" in the surrounding air, it can start to rain, snow, and hail What is streamflow? How do streams get their water?

To learn about streamflow and its role in the water cycle, continue reading. Note: This section of the Water Science School discusses the Earth's "natural" water cycle without human interference. Perhaps you've never seen snow. Or, perhaps you built a snowman this very afternoon and perhaps you saw your snowman begin to melt. Regardless of your experience with snow and associated snowmelt, runoff from snowmelt is a major component of the global movement of water, possibly even if you live where it never snows.

For the water cycle to work, water has to get from the Earth's surface back up into the skies so it can rain back down and ruin your parade or water your crops or yard. It is the invisible process of evaporation that changes liquid and frozen water into water-vapor gas, which then floats up into the skies to become clouds. The atmosphere is the superhighway in the sky that moves water everywhere over the Earth.

To address this, many organizations are turning to the amazing yet complex wealth of Earth data, which can be used to Read More. Thursday, July 2, To reduce risks from natural disasters and build climate resilience, decision makers are using NASA Earth observations to develop index-based insurance products and protect low-income customers in Central America, especially in the region known as the Dry Corridor.

Read More. Wednesday, April 22, Satellite Data Empowers Farmers. Tuesday, April 21, This means that it does not have enough freshwater resources to meet the needs of all the people who live there. Drought and the Australia Wildfire Season. Thursday, March 12, Droughts and dry, arid conditions are naturally occurring phenomena in Australia. Such an environment is conducive to wild fires, which are started mainly by lightning and can occur throughout the year, but typically emerge between October and April and are most prevalent during the Southern Hemisphere summer; they are part of the seasonal cycle in Australia.

Because this water flows directly into rivers and streams it is sometimes referred to as streamflow. The runoff and streamflow steps of the water cycle play a key part in making sure water gets back into the oceans to keep the water cycle going.

How so? Well, unless rivers are diverted or dammed up, all of them eventually empty into the ocean! Not all of the water that precipitates ends up as runoff. Some of it soaks into the ground -- a water cycle process known as infiltration. At this stage, the water is pure and drinkable. Some of the water that infiltrates the ground fills aquifers and other underground stores. Some of this groundwater finds openings in the land surface and re-emerges as freshwater springs.

And still, some of it is absorbed by plant roots and ends up evapostranspiring from leaves. Those amounts that stay close to the land surface, seep back into surface bodies of water lakes, oceans where the cycle starts all over again. Thirsty for more water cycle visualizations? Check out this student-friendly water cycle diagram , courtesy of the U.

Geological Survey. And don't miss this USGS interactive diagram available in three versions: beginner, intermediate, and advanced. Activities for each of the water cycle's main processes can be found at the National Weather Service's Jetstream School for Weather Hydrologic Cycle page.

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