Cloud pattern on Jupiter

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Cloud pattern on Jupiter

The cloud pattern on Jupiter is the visible system of colored cloud tops in the atmosphere of the planet Jupiter, remarkable for its stability. Astronomers have given names to parts of this pattern, using the word zone for the light stripes, and belt for the dark stripes, along various latitudes. The pattern and intensity of its belts and zones are famously variable, often changing markedly from opposition to opposition.

[edit] Names

There are six major belts on Jupiter:

• North and South Equatorial belts
• North and South Temperate belts
• N. North and S. South Temperate belts

There are seven major zones:

• Equatorial zone
• North and South Tropical zone
• North and South Temperate zone
• N. North and S. South Temperate zone

There are two polar regions:

• South polar region
• North polar region

Additionally, there are zones and belts that are more transient in nature and not always visible:

• Equatorial belt
• North Equatorial belt zone (a white zone within the belt)
• South Equatorial belt zone
• North Tropical zone belt (an additional belt inside the white zone)

[edit] Causes

The colored bands in Jupiter's clouds are caused as different-colored layers of clouds become visible.

[edit] Layers

Jupiter's clouds are made up of three different layers, growing colder as they increase in altitude^{[citation needed]}:

• a top layer of ammonia; this layer is white
• below that, a layer of ammonium hydrosulfide; this layer is red or brown
• lowest of all, a layer of water, which is not normally visible

Note: Though the layer of ammonium hydrosulfide should appear white, it is possible that impurities cause the reddish-brown color.

[edit] Circulation Cells

Jupiter, like most planets with atmospheres in the solar system, has multiple circulation cells, caused by the Coriolis Effect, which occurs when a planet with a thick atmosphere spins rapidly. This causes warm air moving away from the equator of the planet and cold air moving away from the poles to become divided into east-west air currents. Jupiter has a particularly strong Coriolis Effect, due to its dense atmosphere and fast rotation, with winds reaching over 400 km/h^{[citation needed]}. This also results in a greater number of circulation cells, compared to Earth's three.

[edit] Rising Gases

Jupiter's core is much hotter than the outer parts of its atmosphere. This causes the gases in its atmosphere to rise, cooling as they go. As they reach the altitude at which they can condense, they do so, while gases that condense at lower temperatures continue to rise. Eventually, the ammonia in the highest level of the clouds crystallizes, like snowflakes, causing the white clouds to disappear, allowing the darker ones below to become visible. Since each circulation cell is a different temperature, the different colors are arranged into bands.

[edit] Storms

The Great Red Spot is a storm feature on the border to the South Equatorial belt and has been observed for at least 300 years.

A feature in the South Temperate Belt, Oval BA, was first seen in 2000 after the collision of three small white storms, and has since appeared to have intensified. It is now approximately half the size of the Great Red Spot, and is starting to turn red. As a result, some scientists have begun calling it "Red Jr." [1]

There are always many smaller storms: brown, low pressure storms, and white, high pressure storms.

[edit] Disturbances

The normal pattern of bands and zones are sometimes disrupted for a period of time, and Astronomers call these events "Disturbances". For example, the longest lived disturbance in recorded history was a "Southern Tropical Disturbance" (STropD) from 1901 until 1939, discovered by Percy B. Molesworth on February 28, 1901. It created a darkened feature over some longitude area in the normally bright Southern Tropical zone.

Various patterns of motion are apparent all across Jupiter at the cloudtop level seen here. The Great Red Spot shows its counterclockwise rotation, and the uneven distribution of its high haze is obvious. To the east (right) of the Red Spot, oval storms, like ball bearings, roll over and pass each other. Horizontal bands adjacent to each other move at different rates. Strings of small storms rotate around northern-hemisphere ovals. The large grayish-blue "hot spots" at the northern edge of the white Equatorial Zone change over the course of time as they march eastward across the planet. Ovals in the north rotate counter to those in the south. Small, very bright features appear quickly and randomly in turbulent regions, candidates for lightning storms.

Scale: The smallest visible features at the equator are about 600 kilometers (about 370 miles) across.
Duration: The 14-frame animation spans 24 Jovian days, or about 10 Earth days. Motion occurs at about 600,000 times actual speed.

[edit] References

1. Bennett, Jeffrey; Donahue, Megan; Schneider, Nicholas; & Voit, Mark (2004). The Solar System: The Cosmic Perspective, (3rd ed.). San Francisco: Pearson Education, Inc. ISBN 0-8053-8930-X