Atmospheric Composition
Jupiter's atmosphere is somewhat complex. The following table gives its composition above the cloudtops to give a comparison to similar tables for the inner planets. The values given below are a guide only because the quantities are variable.
| Name | Symbol | Percentage volume |
| Hydrogen | H2 | 90 |
| Helium | He | 4.5 |
| Methane | CH4 | 7 x 10-2 |
| Ammonia | NH3 | 2 x 10-2 |
| Ethane | C2H6 | 1 x 10-2 |
| Deuterated Hydrogen | HD | 1.8 x 10-3 |
| Water vapour | H2O | 1 x 10-4 |
| Deuterated Methane | CH3D | 3 x 10-5 |
| Phosphine | PH3 | 1 x 10-6 |
| Carbon monoxide | CO | 1 x 10-7 |
| Germanium Tetrahydride | GeH3 ? | 1 x 10-7 |
The first discrete ammonia ice cloud positively identified on Jupiter is shown in this image taken by NASA's Galileo spacecraft. Ammonia ice (light blue) is shown in clouds to the northwest (upper left) of the Great Red Spot (large red spot in middle of figure). This unusual cloud, inside the turbulent wake region near the Great Red Spot, is produced by powerful updrafts of ammonia-laden air from deep within Jupiter's atmosphere. These updrafts are generated by the turbulence induced in Jupiter's massive westward-moving air currents by the nearby Great Red Spot.
This false-color image was composed from several near-infrared color images obtained by the Galileo's near-infrared mapping spectrometer on June 26, 1996. Reddish-orange areas show high-level clouds, yellow areas depict mid-level clouds, and green areas depict lower-level clouds. Darker areas are cloud-free regions. Light blue depicts regions of middle-to-high-altitude-level ammonia ice clouds. The Great Red Spot, which has existed for at least 300 years, is the oldest and largest weather system in our solar system. It measures over 20,000 kilometers wide (over 12,400 miles), which is about twice as wide as Earth.
Text and image courtesy of JPL / NASA
Beginning with seven images taken at uneven time intervals, this
sequence was made by using information on wind speeds derived
from actual Jupiter images to create evenly spaced time steps
throughout. The final result is a smooth movie sequence
consisting of both real and false frames.
The view is of the opposite side of the planet from Jupiter's Great Red Spot. The region shown reaches from 50 degrees north to 50 degrees south of Jupiter's equator, and extends 100 degrees east-to-west, about one-quarter of Jupiter's circumference. The smallest features are about 500 kilometers (about 300 miles) across.
Towards the end of the sequence, a shadow appears from one of Jupiter's moons, Europa.
The movie shows the remains of a historic merger that began several years ago, when three white oval storms that that had existed for 60 years merged into two, then one. The resulting oval is visible in the lower left portion of the movie.
The movie also shows zonal jets that circle the planet on constant latitudes. Winds seen moving toward the left (westward) correspond to features that are rotating a little slower than Jupiter's magnetic field, and winds moving the opposite direction correspond to features that are rotating a little faster than the magnetic field. Since Jupiter has no solid surface, the rotation of the magnetic field is the point of reference for the rotation of the planet.
Text and image courtesy of JPL / NASA / University of Arizona
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