Following the disappearance of Air France Flight 447 over the Atlanticocean, AccuWeather.com meteorologists have been monitoring the weather patternsin the tropics, including the Intertropical Convergence Zone (ITCZ). So, whatexactly is the ITCZ, and how does it affect the weather over the equator?The ITCZ is one of Earth's largest and most influential weather systems. Itis a year-round phenomenon that actually helps to drive the world's "weatherengine."The ITCZ surrounds the Earth's tropics over both land and water, although ittends to be best developed over water. It is, as the name implies, a belt ofconverging winds known as the trade winds.Driven by sub-tropical high pressure in both hemispheres, the trade windstend to converge and pile up steamy, water-laden air that is squeezed aloftinto showers and towering tropical thunderstorms. Vast clusters of suchtropical rain have the power to alter the paths of storms in the middlelatitudes as they release immense energy into the atmosphere. These ITCZthunderstorms also have the potential to spin up to form tropical storms andhurricanes.
The ITCZ tends to vary depending on both the time of year and the meridian,or relative location. For instance, it gets drawn into the warmer of the twohemispheres by solar heating during each hemisphere's respective summer.
The Northern Hemisphere has more land mass than the Southern Hemisphere, andbecause of this, it heats more in the Southern Hemisphere during its summer.
The ITCZ reaches farthest from the equator during the Northern Hemispheresummer. Averaged throughout the year and through all meridians of the Earth,the average latitude of the ITCZ is 5 to 10 degrees north of the equator.
The ITCZ also behaves somewhat differently over land than it does overwater. For instance, its behavior is altered dramatically by the cycle ofMonsoon climates in Asia.
On Sunday evening, Air France Flight 447 intersected the ITCZ north of theequator over the open Atlantic Ocean. At the time, there were thunderstormswithin its belt of converging winds, which is a common occurrence. Flyingthrough the ITCZ is not something out of the ordinary, as countless passengerflights have navigated this area routinely for many years.
Story by AccuWeather.com Senior Meteorologist Jim Andrews
