Learn About the Water Cycle
Author: Terry Newhaven
The water cycle, also known as the hydrologic cycle, describes the movement of water below and above the earth’s surface. The water cycle is a basic component for sustaining life on earth. It helps to purify water, provide freshwater to the land, and transport minerals to various parts of the Earth. Water covers 70 % of the Earth’s surface and 97.5% of the Earth’s water is found in oceans. Only about 2.4% of water is on land while the atmosphere holds about 0.001% of the total water content. The total precipitation of water on earth is more than 30 times the content which the atmosphere can hold. The water cycle passes through a number of processes in one cycle.
Evaporation is a process in which water transforms into gas and moves into the atmosphere. Solar radiation is needed for evaporation of water from the surface of major water reservoirs. Transpiration from plants is also included in evaporation.
Water found in plants and soil is transformed into vapor through the process of transpiration. The water vapor contained in the plant is lost through the roots, flowers, stems, and leaves. The stomata in the leaves allow transpiration to take place on the surface.
Condensation is the opposite of evaporation. The gaseous phase of water is changed to the liquid phase. The water vapor converts into droplets of water to form clouds or fogs. This process is called condensation.
Air currents are formed by pressure, temperature or impurity differences in atmospheric concentration. The air current moves the vapors up. In low temperature, the water condenses to form clouds. Air currents transport clouds from one place to another.
The clouds of condensed water vapor collide, growing in size and weight. Later, it falls to the surface of earth as precipitation. Rain is the most common form of precipitation. Other forms include fog drip, snow, hail, and sleet.
Infiltration refers to the process in which the precipitated water flows into the ground. The water either collects in the soil to form soil moisture or it gets collected below the earth’s surface to form groundwater.
There are a number of methodologies by which the movement of water takes place in the various regions of Earth. The movement of water is called runoff. Some of the ways in which water is stored on the Earth’s surface are lakes and reservoirs. The water can evaporate from the surface and it can be extracted into the soil for agriculture. In the pure form, water can be used by human beings for drinking and cleaning.
The content of water on earth remains constant as water moves from one form of reservoir to another. Water can be found in the form of ice, vapor or liquid. It can be found in river or oceans. The hydrologic cycle starts as evaporation of water takes place from the surface of ocean due to the heat of sun. At low temperatures, water droplets condense and provide heat to the surrounding environment. The condensed water forms clouds which are transported to other places by air currents. The clouds collide and result in precipitation of water which can remain stored on the caps of mountains for millions of years or it can melt to join a river which, subsequently, falls back into the ocean.
Follow these links to learn more about the water cycle.
Popular Pond Supplies
- Droplet: Follow little Droplet to learn about the water cycle.
- The Water Cycle: Bright, fun description with diagram.
- Cycle: The USGS provides a summary of the water cycle.
- Animation: Discover the water cycle in this animated picture.
- Interactive Lesson: An interesting way to learn about the water cycle.
- Game: Play this game to understand the water cycle.
- Round & Round It Goes: Click on the different phases to get more details.
- Review: A simple explanation of the process.
- Fun Facts: Bolster your knowledge of the water cycle with these facts!
- Hydrologic Cycle: A more detailed description of the water cycle.