NORTH CAROLINA THERMAi/'J&J/fS/ V ; ?'/ \ \\ \ //41 



genial stratum upon the top of the lower or frost stratum ; and hence, 

 on cold, frosty nights, is produced the phenomenon of the 'Vernal 

 Zone. 7 ' 



Of course such a phenomenon must be explained in general upon 

 the theory of the nocturnal stratification of layers of the atmosphere, 

 having different amounts of moisture and caloric, of which we so 

 often see examples when the mist settles in the valleys at a given 

 level, which, if the temperature be sufficiently low, would also be 

 the frost line, or when often, on a summer's day, from a mountain- 

 top the white cumuli may be seen stretching away in long lines at a 

 well-defined altitude. But in these cases we have no such visible and 

 exact demarcation of the warmer stratum on its upper side. 



Prof. Le Conte, already quoted, says: "The 'frostless zones' coin- 

 cide with the nocturnal and morning 'fog-belts' of the spring months. 

 The uniform pressure of these white circumscribed belts of fog on 

 the flanks of the mountain spurs during the early morning hours 

 imparts a striking feature to *he scenery of these valleys. When 

 illuminated by the bright morning sun they appear like girdles of 

 cotton-wool of moderate width, encircling the peaks at the height of 

 200 or 300 feet above the adjacent valleys ; and their cumulus-like 

 whiteness, contrasted with the verdure above and below them, is no 

 less striking than it is beautiful." 



The latter circumstance seems to furnish an explanation of the 

 physical cause of the so-called "Thermal Belt" ; for the constant 

 fogs at night and in the morning not only prevent refrigeration by 

 obstructing terrestrial radiation, but, during the condensation of 

 vapor in the process of fog-formation, there must be developed an 

 enormous amount of heat jus't at this zone. Why this condensation 

 of aqueous vapor should be so persistently restricted to a belt of only a 

 few hundred feet in vertical thickness is a question much more diffi- 

 cult to answer. The observations of intelligent residents of the moun- 

 tain valleys in the southern divisions of the Appalachian chain will 

 doubtless verify or disprove the general coincidence of the "frostless 

 zone" with the "fog-belt." 



This piedmont region, not merely that section technically so-called, 

 but the zone along and around the southern Appalachians having an 

 elevation from 1,000 to 2,500 feet above sea-level, possesses attrac- 

 tions as regards beauty and grandeur of scenery, fertility and variety 

 of soil, equability and salubrity of climate, not to be surpassed in the 

 Union. 



If, in addition, these thermal belts exist and extend generally 

 among those ranges, offering exemption from certain forms of dis- 

 ease, with exceptionally favorable facilities for fruit culture, a knowl- 

 edge of the facts should be more generally diffused. 



These facts point out this region as the best place to be found for 

 the cultivation of celery, cauliflower, tomatoes, and other vegetables 

 for canning; raspberries and strawberries for shipment and preserv- 



