Raphael Semmes, Memoirs of Service Afloat During the War Between the States

[607] so, all elasticity departs from the atmosphere, and officers and crew lose their cheerfulness. They feel all the lassitude and weariness of men in a perpetual vapor-bath. The sailor no longer mounts the ratlines, as if he had cork in his heels, but climbs up sluggishly and slothfully, devoid of his usual pride to be foremost. In other words, though not absolutely sick, he is ‘under the weather.’ The rays of the sun being perpetually excluded, the thermometer stands lower under the Cloud Ring, than on either side of it. At least this is the normal condition. Sometimes, however, the most oppressive heats occur. They are local, and of short duration. These local heats are occasioned as follows: When a cooler stratum of the upper air sweeps down nearer the earth than usual, bringing with it the dew-point, condensation takes place so near the surface, that the rain-drops have not time to cool, at the same time that an immense quantity of latent heat has been liberated in the act of condensation. At other times, when the dew-point is far removed from the earth, the latent heat is not only thrown off at a greater distance from us, but the rain-drops cool in their descent, and greatly reduce the temperature.

The Cloud Ring is being perpetually formed, and is perpetually passing away. Fresh volumes of air charged as described, are constantly rushing in from the north and from the south, and as constantly ascending, parting with a portion of their water, and continuing their journey to the poles, in obedience to the laws providing for the equal distribution of rain to the two hemispheres, before explained. The Cloud Ring encircles the entire earth, and if it could be viewed by an eye at a distance from our planet, would appear like a well-defined black mark drawn around an artificial globe. Its width is considerable, being from three to six degrees.

It remains to speak of the offices which this remarkable ring performs. It is an important cog-wheel in the great atmospherical machine, for the distribution of water over the earth; but, besides its functions in the general system, it has local duties to perform. These are the hovering by turns over certain portions of the earth, giving them an alternation of rain and sunshine. In short, it causes the rainy, and dry seasons,