Climate and weather Movements of the Earth Types of precipitation Climate graphs  

Climate and weather

  • Difference between climate and weather:  The difference between weather and climate is a measure of time. Weather is what conditions of the atmosphere are over a short period of time, and climate is how the atmosphere "behaves" over relatively long periods of time.
  • What factors affect climate?
  1. LatitudeTemperature range increases with distance from the equator. Also, temperatures decrease as you move away from the equator. This is because the suns rays are dispersed over a larger area of land as you move away from the equator. This is due to the curved surface of the earth. In addition polar regions are colder because the suns rays have further to travel compared to place on the equator.
  2. Altitude: Temperatures decrease with height. The air is less dense and cannot hold heat as easily.
  3. Winds: If winds are warm - they have been blown from a hot area - they will raise temperatures. If winds have been blown from cold areas they will lower temperatures.
  4. Distance from the sea: Land heats and cools faster than the sea. Therefore coastal areas have a lower temperature range than those areas inland. On the coast winters are mild and summers are cool. In inland areas temperatures are high in the summer and cold in the winter.

  • Types of Climate

We can distinguish 3 basic climate zones:
- A hot zone: between the Tropic of Cancer and the Tropic of Capricorn. High temperatures all year round (Tropical climate and Dry climate)
- A warm zone: between the tropics and the polar circles. Warm temperatures although there is variation among seasons (Mild climate)
- A cold zone: within the polar circles. Cold temperatures all year round (Continental and Polar climate)

Movements of the Earth

The movements of the Earth affect the temperatures. Thanks to the rotation movement we get day time and night time. Thanks to the revolution movement, we get 4 different seasons: spring, summer, autumn and winter.  Learn more here.

Types of precipitation

Precipitation is any form of moisture which falls to the earth. This includes rain, snow, hail and sleet.
Precipitation occurs when water vapour cools. When the air reaches  condensation point  the water vapour condenses and forms tiny droplets of water. These tiny droplets of water form clouds.
Complex forces cause the water droplets to fall as rainfall.
All rain is the same. It happens as the result of warm, moist air being cooled, leading to condensation and in turn rain. The following examples show three different ways air is cooled causing rainfall.

Relief rainfall

Stage 1.
Warm wet air is forced to rise over high land.

Stage 2.
As the air rises it cools and condenses. Clouds form and precipitation occurs.

Stage 3.
The drier air descends and warms.

Stage 4.

Any moisture in the air (e.g. cloud) evaporates.

Convectional rainfall

Stage 1.

The sun heats the ground and warm air rises.

Stage 2

As the air rises it cools and water vapour condenses to form clouds.

Stage 3.
When the condensation point is reached large cumulonimbus clouds are formed.

Stage 4.

Heavy rain storms occur. These usually include thunder and lightening due to the electrical charge created by unstable conditions.

Frontal rainfall

Stage 1.
An area of warm air meets and area of cold air.

Stage 2.
The warm air is forced over the cold air

Stage 3.
Where the air meets the warm air is cooled and water vapour condenses.

Stage 4.
Clouds form and precipitation occurs

Climate graphs
  • What is a climate graph? Climate can be displayed on a graph. A climate graph contains two pieces of information. The amount of rainfall (precipitation) and the temperature of an area. The temperature is shown as a line and the rainfall is displayed as bars. The figures are usually calculated as an average over a number of years. This reduces the impact of any anomalies in the weather affecting the statistics.
  • Have a look at the climate graphs of different cities around the world. Answer these questions

  1. Which city is hotter in July, London or Hohhot?
  2. Which city is colder in December, Yuma or Daily Waters?
  3. Name the ciy with the highest rainfall in April
  4. Name the city with the lowest rainfall in October