452 METEOROLOGY. 



a strong nortlieiiy wind, the return of the regular trade-Nvind, witli much 

 greater intensity than usual, and vessels arriving after short passages 

 bring the intelligence of the i)redicted gale and its disastrous conse- 

 quences. 



Colored bands diverging from the setting sun in the west, and con- 

 verging to an opposite point in the east, are frequently seen through 

 the summer and autumn in great beauty. 



Eemarks. — The rainy season in the northern tropics takes place when 

 the sun, having a northern declination, heats in the greatest degree the 

 land during the day, producing ascending columns of air, which, carry- 

 ing up the vapor it contains into higher and colder regions cause it to 

 be precipitated in rain, the precipitation commencing as soon as the 

 heat from the sun begins to diminish a little after midday. The phe- 

 nomenon mentioned hj Mr. Latimer in regard to the occasional cessa- 

 tion of the trade- winds may possibly be connected with the occurrence 

 of storms on the continent of aSTorth America, or perhaps with the re- 

 markable wind known in Texas as the " norther." This wind prevails 

 from the Mississippi River to the Kio Grande and commences about the 

 1st of September and ends about the 1st of May. The day previous is 

 marked by an unusual warmth and closeness of the atmosphere and an 

 almost perfect calm. Tlie first appearance of the tempest is a cloud in 

 the north, which approaches the observer sometimes with great. and at 

 other times with less velocity, and frequently passes over his head in a 

 series of arches composed of dense clouds separated by lighter portions. 

 The thermometer frequent! 3' falls 30 degrees. On one occasion recorded 

 the temperature fell in the course of three hours from 75° F. to a 

 degree sufficient to produce ice an itich thick. After a day or two the 

 norther is followed by an unusual cold wind from the south, as if the 

 norther were returning. It is said to be most intense near Corpus 

 Christi, Texas, and that it does not occur in Florida. 



The norther is probably due to a stratum of air along the border of 

 the Gulf, abnormally moist and consequently heated, produced by a 

 surface current from the south, which gradually attaining a state of 

 unstabh' equilibrium is suddenly forced upward into a higher region by 

 a heavier wind from the north. The violence of the wind, and conse- 

 quently the intensity of the cold, will depend ui^on the distance north- 

 ward to which the moist stratum extends previous to its overturn by 

 the heav}' air from the north. The norther, it is said, is not felt at sea 

 in the Gulf. This would indicate what we would readily suppose, that 

 the greatest rarefaction of air due to heat and moisture takes place over 

 the laud along the borders of the water. — [J. H.] 



