Our clouds are formed by the action of the sun, producing evaporation of water; on Jupiter, whose mean distance from the sun is more than five times as great as ours, the intensity of the solar rays is reduced to less than one twenty-fifth part of their intensity on the earth, so that the evaporation can not be equally active there, and the tendency to form aerial currents and great systems of winds must be proportionally slight.

In brief, the clouds of Jupiter are probably of an entirely different origin from that of terrestrial clouds, and rather resemble the chaotic masses of vapor that enveloped the earth when it was still in a seminebulous condition, and before its crust had formed.
Although the strongest features of the disk of Jupiter are the great cloud belts, and the white or colored spots in the equatorial zone, yet the telescope shows many markings north and south of the belts, including a number of narrower and fainter belts, and small light or dark spots.

None of them is absolutely fixed in position with reference to others.

In other words, all of the spots, belts, and markings shift their places to a perceptible extent, the changes being generally very slow and regular, but occasionally quite rapid.

The main belts never entirely disappear, and never depart very far from their mean positions with respect to the equator, but the smaller belts toward the north and south are more or less evanescent.