Internet Geography - GeoTopics - Weather and Climate

Climatic Zones

The world has several climatic zones. These are summarised on the map below.

(Image courtesy of the UK Meteorological Office)

The classification is based on maximum and minimum temperatures and the temperature range as well as the total and seasonal distribution of precipitation.

Simple summary of climatic zones:

Polar - very cold and dry all year
Temperate - cold winters and mmild summers
Arid - dry, hot all year
Tropical - hot and wet all year
Mediterranean - mild winters, dry hot summers
Mountains (tundra) very cold all year

What factors affect climate?

There are 5 factors which affect climate. These are summarised below:

Latitude

Temperature 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.

Altitude

Temperatures decrease with height. The air is less dense and cannot hold heat as easily.

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.

Distance from the sea (continentality)

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.

Aspect

Slopes facing the sun are warmer than those that are not. Thus south facing slopes in the northern hemisphere are usually warm. However, slopes facing north in the southern hemisphere are warmest.

Climate Graphs

Climate can be displayed on a graph. A climate graph contains two pieces of information. The amount of rainfall 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.