Class 8 Social Studies |  Weather, Climate and Vegetation

Definitions

- Weather can be defined as the state of atmosphere of a particular place and time (usually 24 hours) in regards to heat, cloudiness, sunshine, wind, rain and more.
- Climate is the weather conditions of an area in general over a long period of time, usually 30-35 years.
- Vegetation are the plants collectively found in a particular habitat.

Weather

Traditional Methods of Observing Weather

Since our ancestors, weather has been a vital aspect of our lives. Here are some ways traditional people used to observe weather
- Migration of birds and insects: Birds and insects migrate to avoid bird weather such as extreme heavy rainfall.
- Presence of dew. - dew in the morning signifies likelihood of no rain during the day.
- Speed and direction of wind
- Shedding of leaves of some trees
- Appearance of certain clouds in the sky
This are just the main methods that some people still use today. There are many more.
Today, the main methods of observing weather are use of satellites and a weather station which is shown in the diagram below.

Here are the main types of weather symbols you will come across in your studies

Observation, Measurement, Recording of Elements of Weather

a) Temperature

- Degree of hotness or coldness of an object or a place
- It is measured using a thermometer
- The units for measuring temperature are Degrees Centigrade (°C)

A simple thermometer shown above
Did you know the main types of thermometer? We have a simple thermometer (shown above) and a Six's maximum and minimum thermometer. A simple thermometer has only mercury while a Six's maximum and minimum thermometer has mercury (shows maximum temperature) and alcohol (shows minimum temperature).

b) Rainfall

- Rainfall can be defined as the amount of water that falls from the sky.
- It is usually measured using a rain gauge
- The units of measurement are Millimeters (mm)

This is a rain gauge

c) Wind

- Wind can be defined as moving air.
- Usually, wind is described in terms of direction, strength and speed.
- The Wind direction is measured using both the windsock and a wind vane

- An anemometer is used to measure the speed of wind.

d) Air Pressure

- The is the pressure exerted on earth by air. (Atmospheric Pressure)
- It is measured using a Barometer
- It is measured in Millimeters of Mercury (mmHg) or Millibars
Below is a simple barometer that is used in experiments in schools

A simple barometer

d) Humidity

- it is defined as the amount of water vapour in the air
- it is measured using a hygrometer
- the unit of measurement is percentage (%)

A hygrometer
Due to their sensitivity, a hygrometer and a thermometer are placed inside a Stevenson's screen in a weather station.

Climate

Climate can be described as:
- Hot and Wet: has high temperatures and high rainfall (equatorial climate)
- Cool and Wet: has low temperatures and high rainfall (Mountain Climate)
- Hot and Dry: has high temperatures and low rainfall (desert and semi-desert climates)
Equatorial climate, Savannah climate, Mediterranean climate, Mountain climate, Desert and Semi-desert climate are the main climates experienced in almost all regions in Africa.

Vegetation

- Vegetation refers to the different plants found in a place or habitat.
- Natural vegetation is the plant cover that grows in a place under natural conditions.
- Vegetation is mainly influenced by the climate of the region
Equatorial rain forest (Tropical rain forest), Tropical Savannah climate, Mediterranean vegetation, Mountain vegetation, Temperate grasslands, Desert and Semi-desert vegetation are the main vegetations found in Africa.