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Tropical rainfall intensifies while the doldrums narrow

06 May 2016

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Silence is not golden around Earth's equator—when trade winds settle down, it spells disaster for sailing ships. In the Northern Hemisphere, trade winds blow southwest toward the equator, whereas Southern Hemisphere trade winds blow northwest. These winds meet at the Intertropical Convergence Zone (ITCZ), a ring around Earth traditionally known as the doldrums for its periodically calm winds that once trapped sail-driven seafarers.

ITCZ is a major tropical atmospheric feature. In this zone, hot air rises through the troposphere as it follows the Hadley cell, causing frequent thunderstorms and heavy rainfall. Seasonal shifts of ITCZ toward and away from the equator give rise to the intensely wet and dry seasons experienced by residents of the tropics. Forecasts of future global weather patterns depend heavily on accurately modeling the characteristics of ITCZ, but scientists have struggled to objectively identify ITCZ using existing measurements. Now Wodzicki and Rapp have improved upon previous efforts to identify ITCZ's central location, its northern and southern boundaries, and the monthly intensity of the rainfall it causes.

Source: EOS

Image credit: NASA GOES Project Science - This satellite image shows a textbook Intertropical Convergence Zone (ITCZ)

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