Page:Physical Geography of the Sea and its Meteorology.djvu/419

Rh 732. The fogs of Newfoundland.—By its discovery we have clearly unmasked the very seat of that agent which produces the Newfoundiand fogs. It is spread out over an area frequently embracing several thousand square miles in. extent, covered with cold water, and surrounded on three sides at least with an immense body of warm. May it not be that the proximity to each other of these two very unequally heated surfaces out upon the ocean would be attended by atmospherical phenomena not unlike those of the land and sea breezes? These warm currents of the sea are powerful meteorological agents. I have been enabled to trace in thunder and lightning the influence of the Gulf Stream in the eastern half of the Atlantic as far up as the parallel of 55° Is., for there, in the dead of winter, a thunder-storm is not unusual.

733. Aqueous isothermal lines.—These isothermal lines of 50°, 60°, 70°, 80°, etc., may illustrate for us the manner in which the climates in the ocean are regulated. Like the sun in the ecliptic, they travel up and down the sea in declination, and serve the monsters of the deep for signs and for seasons.

734. The meeting of cool and warm waters.—It should be borne in mind that the lines of separation, as drawn on Plate IX., between the cool and warm waters, or, more properly speaking, between the channels representing the great polar and equatorial flux and reflux, are not so sharp in nature as this plate would represent them. In the first place, the plate represents the mean Dr average limits of these constant flows—polar and equatorial; whereas, with almost every wind that blows, and at every change of season, the line of meeting between their waters is shifted. In the next place, this line of meeting is drawn with a free hand on the plate, as if to represent an average ; whereas there is reason to believe that this line in nature is variable and unstable as to position, and as to shape rough and jagged, and oftentimes deeply articulated. In the sea, the line of meeting between waters of different temperatures and density is not unlike the sutures of the skull-bone on a grand scale—very rough and jagged; but on the plate it is a line drawn simply with a free hand, merely for the purpose of illustration.

735. The direction of aqueous isotherms on opposite sides of the sea.—Now, continuing for a moment our examination of Plate IV., we are struck with the fact that most of the thermal lines there drawn run from the western side of the Atlantic towards the