The Fundamentals of the Intertropical Convergence Zone

The ITCZ: The Wettest Part of the Planet

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Near the equator, from about 5 degrees north and 5 degrees south, the northeast trade winds and southeast trade winds converge in a low-pressure zone known as the Intertropical Convergence Zone (ITCZ).

Solar heating in the region forces air to rise through convection which results in the accumulation of large thunderstorms and plethora of precipitation, spreading rain around the Equator year-round; as a result of this, combined with its central location on the globe, the ITCZ is a key component of the global air and water circulation system.

The location of the ITCZ changes throughout the year, and how far from the equator it gets is largely determined by the land or ocean temperatures underneath these currents of air and moisture—otter oceans yield less volatile change while varying lands cause varying degrees in the ITCZ's location.

The Intertropical Convergence Zone has been called the doldrums by sailors due to the lack of horizontal air movement (the air simply rises with convection), and it's also known as the Equatorial Convergence Zone or Intertropical Front.

The ITCZ Doesn't Have a Dry Season

Weather stations in the equatorial region record precipitation up to 200 days each year, making the equatorial and ITC zones the wettest on the planet. Additionally, the equatorial region lacks a dry season and is constantly hot and humid, resulting in large thunderstorms formed from the convectional flow of air and moisture.

The precipitation in the ITCZ over land has what's known as a diurnal cycle where clouds form in the late morning and early afternoon hours and by the hottest time of the day at 3 or 4 p.m., convectional thunderstorms form and precipitation begins, but over the ocean, these clouds typically form overnight to produce early morning rainstorms.

These storms are generally short in duration, but they make flying quite difficult, especially over land where clouds can accumulate at altitudes up to 55,000 feet. Most commercial airlines avoid the ITCZ while traveling across continents for this reason, and while the ITCZ over the ocean is usually calmer during the day and night and only active in the morning, many boats have been lost at sea from a sudden storm there.

The Location Changes Throughout the Year

While the ITCZ remains near the equator for most of the year, can vary in as much as 40 to 45 degrees of latitude north or south of the equator based on the pattern of land and ocean beneath it.

The ITCZ over land ventures farther north or south than the ITCZ over the oceans due to the variations in land and water temperatures—with the zone mostly staying close to the Equator over water but varying throughout the year over land.

In Africa in July and August, for instance, the ITCZ is located just south of the Sahel desert at about 20 degrees north of the Equator, but the ITCZ over the Pacific and Atlantic Oceans is usually only 5 to 15 degrees North; meanwhile, over Asia, the ITCZ can go as far as 30 degrees North.

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Rosenberg, Matt. "The Fundamentals of the Intertropical Convergence Zone." ThoughtCo, Feb. 13, 2018, thoughtco.com/itcz-1434436. Rosenberg, Matt. (2018, February 13). The Fundamentals of the Intertropical Convergence Zone. Retrieved from https://www.thoughtco.com/itcz-1434436 Rosenberg, Matt. "The Fundamentals of the Intertropical Convergence Zone." ThoughtCo. https://www.thoughtco.com/itcz-1434436 (accessed April 20, 2018).