This Unit is about Water and how it works.

The water cycle:

Sources of water

  1. Natural sources of water
  2. Rivers
  3. Swamps
  4. Lakes
  5. Rainfall

Artificial sources of water

  1. Taps
  2. Tanks
  3. Bore holes
  4. Wells

Properties of water

It has no colour

It has no taste

It has no smell

It takes the shape of the container

Water in air

This is called water vapour

Formation of water vapour

  1. Through evaporation from water bodies
  2. Through transpiration

Importance of water vapour

  1. It changes into clouds on condensation
  2. The clouds fall as rain


The drops that fall down from the clouds in the sky.


The water collected on the ground from the rain drops

The water cycle

This is the process by which rain is formed.

It involves

  1. Evaporation
  2. Transpiration
  3. Condensation

Evaporation is the change of water from liquid to gas.

Transpiration is the loss of water from a plant to the atmosphere through leaves as vapour.

Condensation is the change of state from gas to liquid.

During the water cycle;

  1. The sun heats the water bodies and vegetation
  2. Evaporation takes place from the water bodies and transpiration takes place in plants
  3. The water vapour rises up into the sky and condenses to form clouds
  4. The clouds become heavy and fall down as rain


Clouds are formed when water vapour in the sky condenses.

Types of clouds

  1. Cirrus—highest and lightest clouds
  2. Stratus
  3. Cumulus
  4. Nimbus—heaviest clouds

Effects of clouds on the environment

  • Clouds block direct sunlight. This reduces the brightness in our environment.
  • Clouds lower the temperature in our environment by reducing heat from the sun.
  •  Clouds bring rain.

Effects of rain on the environment

  1. Rain reduces temperature in the environment
  2. Rain reduces dust
  3. Rainfall softens soil

The weather chart

  1. It is a chart that shows the daily weather changes in our environment.
  2. A weather chart is produced through observation and recording.

The elements of weather in a weather chart include;

  1. How much rainfalls
  2. How much cloud is in the sky
  3. How strong the wind is
  4. How hot is the sunshine
  5. How worm or cool is the air in our surroundings.

Examples of a weather chart

Element of weather Temperature Cloud cover Rainfall Cloud cover Wind movement Sunshine

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