17 September 2014

The Banded Atmosphere of Jupiter

Infrared and Visible Light Image of the Bands of Jupiter 
Image Credit:
One of the most striking features when you look at images of Jupiter is that the atmosphere is not homogeneous, but banded. The Jovian planets are the only planets that display this feature, though Jupiter's is the most pronounced.

The bands are regions of high pressure, rising gas and low pressure, sinking gas separated by high winds. The bands that have high pressure, rising gas are called zones. The zones are bright but cold. They are made up of ice particles that are either ammonia or water ice. The darker bands, called belts, are low pressure, thin clouds that are sinking towards the planet. The belts do not reflect as well as the zones, so appear darker in comparison. The high winds separating the bands are called jets, travel along lines of latitude (east-west), and blow in either the prograde direction or retrograde direction. The prograde jets travel along with the direction of rotation of the Jupiter (from west to east) and the retrograde jets travel against the direction of rotation (east to west). The prograde jets are the transitions from zones to belts (as you move away from Jupiter's equator) and the retrograde jets transition from belts to zones..

The zones and belts are distinct on the surface of Jupiter. Just like Earth, Jupiter has distinct temperature regions based on their location on the planet. They are named as follows:
  • The Equatorial Zone: as the name implies, this is the zone at the equator. Its range is from 7°S to 7°N.
  • The North and South Equatorial Belts: the belts just north and south of the Equatorial Zone. They are reddish in color and range from 7°N (S) to 18°N (S).
  • The North and South Tropical Zones: the South Tropical Zone is where the Great Red Spot is located
  • The North and South Temperate Belts: the South Temperate Belt contains Oval BA (Red Jr.)
  • The North and South Temperate Zones
  • The N-N and S-S Temperate Belts
  • The N-N and S-S Temperate Zones
  • The North and South Polar Regions
A description of the belts and zones
Image Credit:

 
The jets between the zones and belts travel at over 100 m/s (360 kph or 224 mph) and keep the bands from mixing.

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