Climate.
Virginia, as a whole, lies in the region of "middle latitudes," between
36° 30′ and 39° 30′ North, giving it a climate of "means" between the
extremes of heat and cold incident to States south and north of it.
If Virginia were a plain, the general character of the climate of the
whole State would be much the same; but the "relief" of its surface
varies, from that of some of its large peninsulas not more than ten or fifteen
feet above the sea level, to that of large valleys more than two thousand feet
above that level. Long ranges of mountains from three thousand to four
thousand feet in height run entirely across the State, and the waters flow
to all points of the compass. So diversified are the features of the surface
of the State, within its borders may be found all possible exposures to the
sun and general atmospheric movements. It follows from these circumstances
that here must be found great variety of temperature, winds,
moisture, rain and snowfall, beginning and ending of seasons, and all the
periodical phenomena of vegetable and animal life, depending on "the
weather."
The winds are the great agents nature employs to equalize and distribute
temperature, moisture, etc. Virginia lies on the eastern side of
the American continent and on the western shore of the Atlantic Ocean.
It extends to and embraces many of the ranges of the Appalachian system
of mountains, that run parallel to that ocean shore; therefore, it is subject
not only to the general movement of winds, storms, etc., from west to
east, peculiar to the region of the United States, but to modifications of
that movement by the great mountain ranges. It is also subject to the
great atmospheric movements from the Atlantic that, with a rotary
motion, come up from the Tropics and move along the coast, extending
their influence over the Tidewater and Middle regions of the State; sometimes
across Piedmont to the foot of the Blue Ridge, but rarely ever over
or beyond that range. The numberless lines of mountains from the Blue
Ridge to the Cumberland, all the way across its extent from up in Pennsylvania
down into North Carolina unbroken, protect the State against
the cold winds, and storms, and blizzards of the Northwest. This barrier is
absolutely effectual; they never reach this land. The peculiar formation
of the Appalachian chain running southwest into South Carolina and
Georgia, with ranges bearing west into Tennessee and Alabama, protect us
from the cyclones that form in the heated waters of the Gulf and rush
northeast. The formation of the southern end of this range of mountains
turns the southwest storms and tornadoes either up the Cumberland range
northeast or across the Gulf States to the Atlantic Ocean. It has also surface
winds, usually from the Southwest, that follow the trend of the mountains
and bring to them and their enclosed parallel valleys the warmth and
moisture of the Gulf that clothes them all with an abundant vegetation.
The same causes that produced the magnificent forests of the carboniferous
era and furnished the materials for the vast deposits of coal in the
sixty thousand square miles of the great Appalachian coal field that flanks
Virginia on the west, still operate and clothe the surface of the same
region with an abundant vegetation. The laws of the winds make one
region fertile and another barren. America owes its distinction as the
Forest Continent to the situation of its land masses in reference to the prevailing
winds.
Guyot, a standard authority, says: "North America has in the eastern
half a greater amount of rain than either of the other Northern continents
in similar latitudes." . . "The great sub-tropical basin of the
Gulf of Mexico sends up into the air its wealth of vapors to replace those
lost by the winds in crossing the high mountain chains. Hence, the eastern
portions—the great basins of the Mississippi, and the St. Lawrence, and
the Appalachian region—which, without this source of moisture, would be
doomed to drought and barrenness, are the most abundantly watered and
the most productive portions of the continent." "In the eastern half of
the United States the southwesterly winds which prevail in the summer
spread over the interior and the Atlantic plains an abundant supply of
vapors from the warm waters of the Gulf. Frequent, copious showers
refresh the soil during the months of greatest heat, which show a maximum
of rain. Thus the dry summers of the warm-temperate region disappear,
and with them the periodical character of the rains so well marked
elsewhere in this belt."
These quotations show the advantages Virginia has, in this respect,
over the warm-temperate regions of Europe and elsewhere.
