The Weather. 109 



vapour is discharged in clouds. Dome-shaped, cumbrous- 

 looking masses are produced, at a height of 4000 to 8000 feet 

 above the sea, called Cumulus clouds, from their pillow -like 

 appearance. At Quito, and at other places on the equator, 

 these clouds fh'st make their appearance in the morning. They 

 increase in size and numbers till the afternoon, and at the same 

 time subside in height until the sky is completely overcast 

 with a species of clouds called Cnmulo-stratus, from which rain 

 is immediately discharged in torrents. With the disappearance 

 of the sun these clouds subside yet further, and cumulo- stratus 

 then collects itself at evening into horizontal stripes of clouds, 

 called Stratus from their level distribution. These clouds only 

 accompany fine and sunny weather peculiar to a dry condition 

 of the air. 



In mountainous countries, a great variety of clouds is 

 produced among the upturned currents of the air. The well- 

 known " caps" upon the summits of certain mountain-peaks — 

 for example, the Mam Tor, or Shaking Mountain, in Derby- 

 shire, the Matterhorn in Switzerland, and the Table Mountain 

 at the Cape of Good Hope — give these mountains the ap- 

 pearance of active volcanoes in perpetual eruption. Being 

 driven to visit a higher and a colder level, the currents of 

 wind discharge their moisture for a time, which they again 

 resume on descending the opposite declivity of the mountain. 

 Near to the Table Mountain, a secondary cap is even formed, at 

 a considerable distance, by a secondary ripple of the wind. 

 The influence of mountain-slopes is, however, confined entirely 

 to the precincts of their valleys. This is most apparent in the 

 fact, that some mountain-ranges are subjected to perpetual 

 rain, while the plains in their immediate neighbourhood are free. 

 In Cumberland, from the summit of Skiddaw, three thousand out 

 of five thousand clouds were reckoned by Crossthwaite to occur 

 below the level of the mountain, whose height is 3150 feet above 

 the sea. The remainder, or by far the smaller number, occurred 

 at greater heights. The reverse would probably be observed 

 on the surrounding level land, for there high clouds are the 

 rule, and those of lower elevations the exception. 



The loftiest clouds of all are the slender whisps of 

 Cirrus — "mares' tails," as they are generally called — whose 

 streaks occur at heights of more than 20,000 feet above the 

 sea. Cirrus is the natural forerunner of a southerly wind. 

 Should its streaks be tangled, and their edges sharp and well- 

 defined, they give short notice of the coining wind. In 

 general they are diffuse, and Cirrus gradually overspreads the 

 sky with a misty, gauze-like veil, called Cirro-stratus. The 

 various appearances of halos, burrs, mock-suns, and mock- 

 moons, are seen in this cloud in perfection, which also gives a 



