Topic One (1.1): Tropical Climates

Introduction

This topic examines rainforest, savanna and monsoon climates.

You will study:

Global distribution and climatic characteristics of humid tropical and seasonally humid tropical environments: the roles of the intertropical convergence zone (ITCZ), subtropical anticyclones, and monsoons.
The key features of temperature and rainfall and their annual and diurnal variations in the humid tropical and seasonally humid tropical environments.

Read and Make Notes

For this topic, you will need to work through pages 187 to 198 of your textbook, completing the Activities at the end of the Section.

Download and Print

Download and print out these resources to accompany your notes:

PRINT - Tropical Climates Download PRINT - Tropical Climates

PRINT - Fig.7.1 Tropical Climates Download PRINT - Fig.7.1 Tropical Climates

PRINT - Fig.7.6 Asian Monsoon Download PRINT - Fig.7.6 Asian Monsoon

PRINT - Fig.7.7 Rainfall Indian Download PRINT - Fig.7.7 Rainfall Indian – Please note - Mumbai should be at 19^oN on this diagram.

PRINT - Fig.7.10 Brunei Darussalam Download PRINT - Fig.7.10 Brunei Darussalam

PRINT - Fig.7.12 Rainfall Brunei Download PRINT - Fig.7.12 Rainfall Brunei

Top Tips

Make sure that you understand the following key points:

The movement of the ICTZ affects different continents differently owing to the location and relief of the land masses and the relevant ocean gyres, and it is important you know the monsoon as well as the rainy/dry seasons of Africa.
The word Monsoon relates to a climate not a rainy season! There is a dry and a wet monsoon.
Air moving over oceans is always picking up moisture, but the warmer the air and the water the more evaporation there is. This accounts for the ‘bend’ in the ITCZ over Africa in June/July as the Western edge of the ITCZ is always over water when it is south of the Equator.

Key Terms

You may find it easier to put your key terms into alphabetical order if you want them as a table (using a computer so you can add to them later) or if you want to get ahead then put them on flashcards with the word on one side and the definition on the reverse which you can use for revision before your exam. Some people like to colour-code their key terms by unit.

The words should be used in addition to those learnt in section 2.2 and 2.3 (AS units).

Monsoon climates are characterised by wind patterns with a pronounced seasonal reversal. The basic cause is the seasonal difference in heating of land and sea on a continental scale.
Air mass is a large body of air where the horizontal gradient (variation) of the main physical properties, such as temperature and humidity, is fairly gentle. It is often referred to as a parcel of air that shares the same characteristics.
Secondary air mass is an air mass that has changed as it has moved away from its original source.
ITCZ or intertropical convergence zone is the area in which the north-east trade winds and the south-east trade winds converge. If there is a difference in temperatures between the winds, the warmer air rises over the denser, colder air and may produce rain.
Ocean currents are the continuous movement of water caused by the wind, Coriolis effect and variations in temperature and density.
El Niño is an irregular occurrence of warm surface water in the Pacific off the coast of South America. It affects global wind and rainfall patterns. It has an opposite which is called La Niña. They work in reverse to one another causing drought or heavy rains in opposite parts of the borders of the Pacific Ocean. They switch in cycles.
Gyre is a large-scale ocean current or group of currents.
Drought is an unexpected short-term shortage of available moisture. It is normally identified as a 14 day shortage from normal of precipitation in meteorology. The change is the key element of this definition – rainfall is lower than normal (not necessarily completely absent though).
Tropical cyclone is a generic name that includes hurricanes (North Atlantic), cyclones (Indian Ocean and the Bay of Bengal) and typhoons (Japan). It is a low pressure system commonly up to 600 km in diameter with wind speeds of up to 300 km/hour (typically 160 km/hour) and bringing up to 30–50 cm of rainfall.
Mudslide is a form of mass movement that tends to flow in channels. The water content is relatively high. Refer back to unit 3 in the AS level.