<P> The atmosphere of Jupiter is home to hundreds of vortices--circular rotating structures that, as in the Earth's atmosphere, can be divided into two classes: cyclones and anticyclones . Cyclones rotate in the direction similar to the rotation of the planet (counterclockwise in the northern hemisphere and clockwise in the southern); anticyclones rotate in the reverse direction . However, unlike in the terrestrial atmosphere, anticyclones predominate over cyclones on Jupiter--more than 90% of vortices larger than 2000 km in diameter are anticyclones . The lifetime of Jovian vortices varies from several days to hundreds of years, depending on their size . For instance, the average lifetime of an anticyclone between 1000 and 6000 km in diameter is 1--3 years . Vortices have never been observed in the equatorial region of Jupiter (within 10 ° of latitude), where they are unstable . As on any rapidly rotating planet, Jupiter's anticyclones are high pressure centers, while cyclones are low pressure . </P> <P> The anticyclones in Jupiter's atmosphere are always confined within zones, where the wind speed increases in direction from the equator to the poles . They are usually bright and appear as white ovals . They can move in longitude, but stay at approximately the same latitude as they are unable to escape from the confining zone . The wind speeds at their periphery are about 100 m / s . Different anticyclones located in one zone tend to merge, when they approach each other . However Jupiter has two anticyclones that are somewhat different from all others . They are the Great Red Spot (GRS) and the Oval BA; the latter formed only in 2000 . In contrast to white ovals, these structures are red, arguably due to dredging up of red material from the planet's depths . On Jupiter the anticyclones usually form through merges of smaller structures including convective storms (see below), although large ovals can result from the instability of jets . The latter was observed in 1938--1940, when a few white ovals appeared as a result of instability of the southern temperate zone; they later merged to form Oval BA . </P> <P> In contrast to anticyclones, the Jovian cyclones tend to be small, dark and irregular structures . Some of the darker and more regular features are known as brown ovals (or badges). However the existence of a few long--lived large cyclones has been suggested . In addition to compact cyclones, Jupiter has several large irregular filamentary patches, which demonstrate cyclonic rotation . One of them is located to the west of the GRS (in its wake region) in the southern equatorial belt . These patches are called cyclonic regions (CR). The cyclones are always located in the belts and tend to merge when they encounter each other, much like anticyclones . </P> <P> The deep structure of vortices is not completely clear . They are thought to be relatively thin, as any thickness greater than about 500 km will lead to instability . The large anticyclones are known to extend only a few tens of kilometers above the visible clouds . The early hypothesis that the vortices are deep convective plumes (or convective columns) as of 2008 is not shared by the majority of planetary scientists . </P>

Which is the most active region of the atmosphere