27 Jan 2024 : Daily Answer Writing

Q1) What do you understand by the Inter-tropical convergence zone (ITCZ)? Discuss the climatic impact of its seasonal shift.

The Inter-tropical convergence zone (ITCZ) is the trough of Low Pressure circumventing the Earth in the tropics, almost parallel to the equator. It follows the movement of sun and traverse towards the North or to the South accordingly.

1. The ITCZ is a belt of low-pressure which attracts the north-east trade winds from northern hemisphere and south-east trade winds form southern hemisphere.
2. It is usually characterised by clouds, thunderstorms, and heavy rainfall along the trough.
3. In summers, with the change in the apparent position of sun towards tropic of cancer, the ITCZ moves northward upto 20°N-25°N latitudes (over the Gangetic plain). This brings monsoon to India and thus known as the monsoon trough.
4. In winters, due to apparent movement of sun toward tropic of Capricorn, the ITCZ moves southward, causing the reversal of wind direction. This results in North East Monsoon in India.

Climatic Impact of Seasonal Shift of ITCZ can be seen from:

1. Precipitation: The areas under the influence of the ITCZ receives the maximum rainfall due to the convergence of trade winds.
2. Temperature: Due to the increased cloud cover and rainfall, the regions associated with ITCZ experience relatively lower temperatures and higher humidity compared to the surrounding.

Hence during January and February, Northern Australia experiences lower temperatures compared to the South.

3. Monsoon: These are the seasonal winds in parts of Asia, Africa and America. Due to the shifting of ITCZ, the distinct reversal pattern of winds forms which impacts the rest of the climatic factors of the region.
4. Cyclones: The low-pressure system when is accompanied with suitable source of moisture, it leads to the formation of tropical cyclones in northern and southern hemispheres during respective summers.
5. Longer term climatic changes:
6. a) Drought: Seasonal movement of the ITCZ can cause droughts in some regions. For example, when the ITCZ is around the Tropic of Cancer, high pressure system is developed in the Southern Hemisphere leading to very low rainfall and droughts in some regions of Africa.
7. b) Flooding: When the impact of ITCZ is paired with other factors like a La-Nina spell or the MJO, it leads to floodings in many parts on India and Indonesia.

Hence, the intertropical convergence zone (ITCZ) is found to have a direct impact on the climate of a region. Study of the same thus becomes essential in order to understand the long-term/ short-term trends in global weather/climatic conditions.

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