How Wind Influences Rainfall with Seasons
Wind plays a crucial role in distributing rainfall across the globe by transporting moisture from oceans to landmasses. The position of trade winds and the Intertropical Convergent Zone (ITCZ) during different seasons significantly influences rainfall patterns.
1. North East Trade Winds (November to April)
- During the winter months, the North East trade winds blow from the subtropical high-pressure zone towards the equatorial low-pressure zone.
- As these winds cross the equator, they are deflected to the west due to the Coriolis force.
- The deflection creates a zone of convergence known as the Intertropical Convergence Zone (ITCZ), where warm, moist air rises and condenses, leading to heavy rainfall.
2. South West Trade Winds (May to October)
- During the summer months, the South West trade winds blow from the subtropical high-pressure zone towards the equatorial low-pressure zone.
- These winds also cross the equator and are deflected to the west by the Coriolis force.
- The ITCZ shifts northward, following the position of the Sun, resulting in a northward shift in rainfall zones.
3. Intertropical Convergence Zone (ITCZ)
- The Intertropical Convergence Zone (ITCZ) is a narrow belt of low atmospheric pressure that encircles the Earth near the equator.
- It is characterized by rising air, convection, and heavy rainfall.
- The ITCZ migrates seasonally, following the path of the overhead Sun, resulting in alternating wet and dry seasons in equatorial regions.
Diagram:
[Image of a diagram showing the position of the North East tradewind, South West trade wind, and Intertropical Convergence Zone (ITCZ) during different seasons]
Seasonal Rainfall Patterns:
- During winter (November to April), the ITCZ is located south of the equator, and heavy rainfall occurs in the Southern Hemisphere (e.g., Brazil, Madagascar).
- During summer (May to October), the ITCZ is located north of the equator, and heavy rainfall occurs in the Northern Hemisphere (e.g., India, Southeast Asia).
- The northern and southern hemisphere trade winds converge at the ITCZ, creating an upward movement of air that leads to cloud formation and rainfall.
- The position of the ITCZ, as influenced by the trade winds, determines the seasonal distribution of rainfall in tropical and subtropical regions.