WEATHER. 



WEATHER. 



their crops, to describe the appearance of a I 

 small cloud, which, from its rapid formation : 

 and disappearance, is likely to escape the ob- 

 servation of most persons, but which, from my 

 own experience, I have found a very faithful 

 forewarner of foul weather. It appears mostly 

 in the mild weather of spring, summer, and 

 autumn, when its warning token becomes most 

 acceptable. It is a small, delicately soft, thin, 

 white, curved cloud, formed suddenly upon the 

 summit of those fine heaped clouds (termed 

 cumuli) which often prevail in warm weather, 

 and appear to tower up to a prodigious height. 

 It is necessary to keep a watchful eye upon the 

 summit of the cumulus. When this little film, 

 which I term " the storm cap," appears, it lies 

 closely over the rounded summit, like a white 

 silken web ; in a very few seconds it will dis- 

 appear, sinking, I suppose, into the cumulus ; 

 but in a little time, and when heavy foul wea- 

 ther threatens, the film again appears, disap- 

 pearing as shortly as before. (Mag. Nat. Hist. 

 vol. iv. p. 444.) 



The following indications have been record- 

 ed, as shown by the predominance of certain 

 of the prismatic colours of the rainbow, but 

 they are perhaps too fanciful to be de- 

 serving of much credence. 1. Red; if this 

 colour be very predominant, wind, or wind and 

 rain, may be expected. 2. Orango ; when the 

 orange colour appears strong and very full, it 

 generally indicates approaching rain. 3. Yel- 

 low; when yellow is more conspicuous than 

 the other colours, it foretells dry weather. 4. 

 Green; approaching rain may be expected 

 when the green is very predominant 5. Blue; 

 fine weather may be expected when the blue is 

 particularly full. 6. Purple ; if the purple be 

 a very full colour, wind and rain may be ex- 

 pected. 7. Violet ; the violet, when very clear, 

 generally indicates approaching fine weather. 

 See RAINBOW. 



The Wind. The earth is surrounded to the 

 extent of 60 miles with an atmosphere, on 

 which all nature mutually depends for life. 

 This ae'rial ocean revolves with our earth 

 round the sun, is very susceptible of motion, 

 and some parts of it is constantly in restless 

 commotion. These commotions are called 

 winds, and are principally caused by heat from 

 the rays of the sun, which, rarefying the air, 

 causes it to ascend ; and the vacuum thus 

 formed is filled up with a colder air from the 

 north and south. 



Wind has been explained in the following 

 manner: Heated air has a tendency to rise, 

 and cold air rushes in to supply its place. 

 Thus the heated air of the equatorial regions 

 rises and gives place to a current sent from the 

 polar regions, which is a process that serves to 

 equalize the temperature of the world. But 

 the polar countries lying near to the axis of 

 the sphere, the air from those regions has not 

 received so much motion as that about the 

 equator, or greatest distance from the axis ; 

 wherefore it arrives at the equator, where the 

 motion of the earth is greater. If it had no 

 motion before, an east wind would be the con- 

 sequence, and the force of that wind would be 

 as the difference between the motion of the 

 earth where the air came from, and that where 

 139 



it arrived: but then, in the northern hemi- 

 sphere, it has a motion to the south; for it is 

 rushing into a vacuum left by the air which 

 rises ; so that the wind will not be from the 

 east, but northeast; and the number of degrees 

 north of the east from which it will blow will 

 depend upon the comparative force of the cur- 

 rent of air from the north to the difference be- 

 tween the earth's motion at the equator and at 

 the polar region, whence the air comes. As 

 there must be a corresponding efflux from the 

 equator higher up, according to this theory the 

 wind should everywhere be northeast or south- 

 west, but it blows in very different directions 

 at different times and places, owing chiefly to 

 circumstances connected with the distribution 

 of land and water, and the variations in tem- 

 perature at different times and places. 



From observing the wind a fair idea of the 

 coming weather may oftentimes be drawn; and 

 yet, as Solomon observes, "he that considers 

 the wind shall never sow;" that is, he that 

 busies himself too much about the wind will 

 become superstitious. The indications to be 

 drawn from observing the direction and changes 

 of the wind must vary in different countries, 

 according to the relative positions of these in 

 regard to the sea, lakes, plains, or mountains 

 covered with snow. For an explanation of 

 some of the phenomena of climate and weather, 

 the reader is referred to preceding articles, 

 under the heads of BAROMETER, CLIMATE ot 

 THE UNITED STATES, &c. 



In all countries, therefore, particular winds 

 are noted for being accompanied with either 

 wet or dry weather. Thus the south and south- 

 west winds bring much moisture into Britain; 

 while those from the north and northeast are 

 cold, dry, and penetrating. Hence the old Eng- 

 lish proverb 



" When the wind 'a in the south, 

 It's in the rain's mouth." 



Not only does this arise from the immense 

 surface of ocean over which these winds sweep 

 south of the equator, the evaporation from which 

 must be prodigious; but from these southerly 

 winds being of a higher temperature, whereby 

 they hold a greater quantity of vapour in sus- 

 pension or solution, the condensation of which 

 must be proportionally greater on arriving in 

 this colder climate. Accordingly, it has been 

 observed that the wind will turn from the north 

 to the south quietly and without rain ; but on 

 returning from the south to the north, will blow 

 hard and bring much rain. Again, if it begin 

 to rain from the south, with a high wind for 2 

 or 3 hours, the wind falls ; but if the rain con- 

 tinues, it is likely to rain for 12 hours or more, 

 and does usually rain until a strong north wind 

 clears the air. For the same reason, winds 

 from the west and southwest are in England 

 considered to bring with them wet weather. 

 (Chambers' Information for the People, No. 58, 

 New Series.) 



A change in the warmth of the weather is 

 often followed by a change in the wind. Thus, 

 the northerly and southerly winds, though com- 

 monly accounted the causes of cold and warm 

 weather, are really the effects of the cold or 

 warmth of the atmosphere. 



5 A 1105 



