Water cycle: the cycle is defined as the continuous movement of water from the atmosphere to the earth and from the earth to the atmosphere.

The water cycle shows the continuous movement of water within the Earth and atmosphere in the form of gas, liquid and solid state. It is a system that includes many different processes.

Liquid water evaporates into water vapor, condenses to form clouds, and precipitates back to earth in the form of rain,

The water cycle, also known as the hydrological cycle, is the continuous process of water circulation on Earth. It involves the movement of water in various forms through the atmosphere, the Earth’s surface, and below ground. The water cycle is crucial for maintaining life and regulating Earth’s climate. It consists of several key stages:

  1. Evaporation: This stage begins with the sun’s heat, which causes water from oceans, lakes, rivers, and other water bodies to change from liquid to vapor or gas form. This process occurs primarily from the Earth’s surface.

Condensation: As water vapour rises into the atmosphere, it cools down at higher altitudes, and the water molecules start to come closer together, forming tiny water droplets. These droplets gather around microscopic particles like dust or salt in the air, creating clouds.

  1. Precipitation: When the water droplets in the clouds become too heavy or the clouds become saturated, the water falls back to the Earth’s surface as precipitation. Precipitation can take various forms, such as rain, snow, sleet, or hail, depending on the temperature and atmospheric conditions.

Infiltration and Surface Runoff: Once the precipitation reaches the ground, some of it may seep into the soil through a process called infiltration. you can read my post on soil water here

This water is then stored as groundwater in underground aquifers or flows to become part of lakes, rivers, and streams. Some of the precipitation, especially during heavy rain or on impermeable surfaces like roads and concrete, runs off directly into rivers and other water bodies. This is called surface runoff.

  1. Transpiration: Transpiration is the process by which plants absorb water through their roots and release it as vapour through tiny openings (stomata) on their leaves. This water vapour also contributes to the water content in the atmosphere.

Sublimation and Melting: In cold regions, solid ice can transition directly to water vapour through a process called sublimation. During warmer periods, snow and ice can melt, turning into liquid water.

  1. Percolation: When water infiltrates the soil, it may continue to move downward through the soil and rock layers until it reaches an impermeable layer or a water table. This process is called percolation and can contribute to groundwater storage.
  2. Groundwater Discharge: Groundwater can discharge into rivers, lakes, and oceans, becoming part of the surface water again. This process is important for maintaining the flow of rivers and supporting ecosystems.

How the atmosphere receives water through the water cycle

v. Water facilitates enzymatic activities occurring in crop plants
vi. It is a constituent of plant protoplasm
vii. The loss of water through transpiration is important for keeping the stomata open in gaseous exchange for respiration and photosynthesis
viii. It has a cooling effect on crops-
ix. It helps to maintain plant tugor or turgidity
x. It helps to sustain life through the water cycles
xi. It helps in seed germination

Forms in which water exists in the soil

The form in which water exists in the soil includes:
i. Hygroscopic water
ii. Capillary water

iii. Gravitational water

Ways of conserving water in the soil during water cycle

i. Stoppage or reduction of surface water run–off ii. Addition of human or organic manure
iii. Removal of weeds to reduce transpiration and water loss
iv. Mulching
v. Cover cropping
vi. Contour ridging can prevent water loss during water cycl
vii. Appropriate tillage
viii. Strip cropping

  1. economic tools for nation building
  2. budgeting
  3. factors affecting the expansion of industries
  4. mineral resources and the mining industries
  5. demand and supply

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