Intertropical Convergence Zone (ITCZ): Causes & Impacts - UPSC Notes

The ITCZ or Intertropical Convergence Zone refers to one of the vital elements of meteorology and climatology. This zone gives major influence on global climate patterns. ITCZ refers to the belt near the equator that has converging trade winds and rising air surrounding the Earth. These exhibit characteristic convective activity frequently forming thunderstorms and giving rise to heavy rainfall. Another name given to it is equatorial convergence zone, also referred to as the doldrums. The location of the ITCZ varies seasonally and influences weather and climate in tropical and subtropical regions.

The topic of the Intertropical Convergence Zone (ITCZ) is highly pertinent to the UPSC Civil Services Examination, specifically under the General Studies Paper I (GS I). This paper covers Geography, which includes Physical Geography, Climate, and Weather Systems. Understanding the ITCZ is crucial for UPSC aspirants as it helps in explaining the climatic variations and weather patterns affecting different regions, especially tropical countries like India.

What is Intertropical Convergence Zone?

The Intertropical Convergence Zone is a region of high confluence between the northeast and southeast trade winds. Its cause is the intense solar heating near the equator that makes the air at those latitudes rise. While warming, moist air is brought upwards, cools and condenses, thus building into cloud clusters that results in precipitation. The ITCZ is not fixed but rather a moving feature, oscillating north and south according to the seasonal variations of solar radiation. This causes a significant impact on the climate and weather patterns within those regions.

Read the article on the Climate of India!

Causes of Intertropical Convergence Zone (ITCZ)

There are several factors driving the ITCZ. These factors include:

• Solar Heating: The equatorial region receives the maximum amount of solar insolation in the entire Earth. This extreme heating makes the air rise up, thus creating a low-pressure zone, which sucks the trade winds towards the equatorial region.
• Earth's Rotation: Due to the Earth's rotation, the Coriolis effect takes place. As a result, the direction of the trade winds changes and the trade winds meet at the equatorial region.
• Seasonal Shifts: The tilt of the Earth's axis leads to seasonal variations in the position of the sun relative to the equator. It means that the ITCZ shifts northward during the Northern Hemisphere summer and southward during the Southern Hemisphere summer.
• Ocean Currents: Circulation patterns in the ocean may affect the positioning and intensity of the ITCZ due to the surface temperature and the moisture content in the air.

Read the article on the Pressure Belts of Earth!

Intertropical Convergence Zone Characteristics

The ITCZ has a number of very notable characteristics:

• High Rainfall: As the moist air ascends in the ITCZ, it cools and becomes saturated and, hence, precipitates heavy rainfall and its frequency is usually very high. The rainfall here is generally above 2000 mm per annum.
• Thunderstorms: Frequent thunderstorms characterise the ITCZ because of heavy convective activities. Such thunderstorms arise when the updrafts are deep and have sufficient moisture content within the rising air.
• Cloud Formation: It is marked by persistent cloud cover mainly due to the formation of convective clouds like cumulonimbus and stratocumulus.
• Seasonal Movement: The ITCZ is not stationary; it migrates north or south of the equator seasonally. This movement depends on the position of the sun and results in wet and dry seasons in tropical regions.
• Low Pressure: The trade winds converge to create a belt of low pressure along the ITCZ, often a zone of weak and variable winds.

Read the article on the Types of Rainfall!

Impacts of the Intertropical Convergence Zone

The ITCZ has broad effects on global climate and weather systems:

• Monsoon Systems: The ITCZ is an essential component in monsoon system development. One example of this is when the Indian Monsoon changes with the northward movement of the ITCZ, especially during the summer months.
• Tropical Rainforests: Areas in the influence of the ITCZ also receive a tremendous amount of rain, as seen in regions like the Amazon Basin and parts of Central Africa, for instance, which support dense tropical rainforests to grow.
• Droughts and Floods: Changes in the ITCZ may lead to extreme weather. When the ITCZ is placed in an abnormal position, it may cause prolonged droughts or excessive rainfall leading to floods.
• Global Circulation Patterns: The ITCZ is part of the Hadley Cell circulation and impacts global atmospheric circulation patterns and energy distribution around the planet.
• Agricultural Seasons: The migration of the ITCZ impacts the agricultural cycles of tropical regions. Farmers can schedule their planting and harvesting accordingly based on the consistent pattern of wet and dry seasons.

Read the article on the Precipitation & Distribution of Rainfall!

We hope your doubts regarding the topic have been addressed after going through the above article. Testbook offers good quality preparation material for different competitive examinations. Succeed in your UPSC IAS exam preparations by downloading the Testbook App here!