Describe the characteristics of the equatorial and monsoon climates and explain how they differ in temperature and rainfall

What this dot point is asking

This outcome asks you to describe the two main tropical climates, equatorial and monsoon, and to explain how they differ in temperature and rainfall. You should be able to recognise each from a climate graph and give reasons for their patterns. The central idea is that both are hot, but the equatorial climate has rain all year while the monsoon climate has a clear wet and dry season driven by changing winds.

The answer

The equatorial climate

The equatorial climate is found near the Equator, including Singapore. Its features are:

• High, constant temperature: monthly means around 26 to 28 degrees Celsius all year, with a very small annual range of only a few degrees, because the Sun is always high in the sky.
• Heavy rainfall every month: often over 2,000 mm a year with no dry season, much of it falling as afternoon convectional thunderstorms.
• High humidity and a lot of cloud.

The monsoon climate

The monsoon climate is found in parts of South and Southeast Asia. Its features are:

• High temperatures all year, but with a slightly larger range than the equatorial climate.
• A clear wet season and dry season, caused by seasonal changes in wind direction. In the wet season, winds blow in from the sea bringing heavy rain; in the dry season, winds blow from the land and rainfall is low.
• Rainfall is therefore uneven through the year, concentrated in the wet months.

How they differ

The main difference is the rainfall pattern. The equatorial climate has rain in every month with no dry season, while the monsoon climate has a marked wet and dry season. The monsoon also has a slightly larger temperature range. Both are hot, so the difference is mainly in how the rain is spread through the year.

Why these climates are so wet

Both climates are wet because the intense tropical heating warms the ground and the air above it, making the air rise (convection), cool and condense into clouds and rain. Near the Equator this happens all year. In the monsoon, the heavy rain comes mainly when moist winds blow in from the sea during the wet season.

Examples in context

Example 1. Singapore's equatorial climate. Singapore is a textbook equatorial location: temperatures stay near 27 degrees Celsius all year with a range of only about 2 degrees, and rain falls heavily in every month, often as dramatic afternoon thunderstorms. There is no dry season, which is exactly what the equatorial climate predicts.

Example 2. The Indian monsoon. Much of India has a monsoon climate, with a hot dry season followed by a wet season when moist winds blow in from the Indian Ocean and bring torrential rain. The sharp switch between dry and wet, driven by the changing winds, is the defining feature of the monsoon climate and the opposite of the equatorial pattern.

Try this

Q1. State two features of the equatorial climate. [2 marks]

• Cue. High constant temperature with a small range; heavy rainfall in every month with no dry season.

Q2. Explain why the monsoon climate has a wet and dry season. [2 marks]

• Cue. Seasonal changes in wind direction: moist winds from the sea bring heavy rain in the wet season, and dry winds from the land give little rain in the dry season.

Q3. State one way you could tell an equatorial climate from a monsoon climate using a climate graph. [1 mark]

• Cue. The equatorial climate has rain in every month (no dry season); the monsoon has a clear dry season.