It is one of Earth`s biggest weather systems. It is to be found operatingduring all 365 days a year. And it actually helps to drive the world`s "weatherengine". It would be what meteorologists have dubbed the IntertropicalConvergence Zone, or ITCZ for short.The ITCZ girdles the Earth`s tropics, both over water and over land,although it tends to be best developed over water. It is, as the name imply, abelt of converging winds, the Trade Winds by name.
Driven by sub-tropical high pressure in both hemispheres, the Trade Windstend to converge and pile up steamy water-laden air. This air 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. And the ITCZthunderstorms can spin up to form tropical storms and hurricanes.
The ITCZ tends to vary depending both upon the time of year and themeridian, or relative location.
For one thing, it gets drawn into the warmer of the two hemispheres by solarheating during the respective summer.
Because the Northern Hemisphere, with its big land masses, heats more in itsssummer than the Southern Hemisphere, the ITCZ reaches farthest from the Equatorduring the Northern Summer. Averaged throughout the year and through allmeridians of the Earth, the average latitude of the ITCZ is 5 to 10 degreenorth of the Equator.
Moreover, the ITCZ behaves somewhat differently over land. For instance, itsbehavior is altered dramatically by the cycle of Monsoon 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. But this is to be expected. Moreover,flying through the ITCZ is something that untold thousands of passenger flightshave navigated routinely for many years.
Story by AccuWeather.com Senior Meteorologist Jim Andrews
