Year: 1878

Why 1t Grors Colder, and sOhy Storms come
an the Short Days.
The year glides around, the seasons


come and go, the nights grow long and


the short days bring their storms and


gloom, yet why these changes occur few


inquire. If the earth moved round the


sun with the axis perpendicular to the


plane Of its orbit, or in the same position


that top, when in swift motion, has to


the floor or level surface on which it


stands, there would be no change of sea-


sons or variation in the length of days.


At the equator, but nowhere else, the sun


would always rise directly in the east and


set in the west, and be Immediately over


head at noon. AS the rays of heat which


fall perpendicularly impart the greatest


warmth, the temperature at the equator


would be higher than it now is, but the


heat distributed over the earth would be
much less. Instead, however, of the axis


of the earth being perpendicular to the
plane of its orbit, it is inclined 232 degrees
toward that plane, or like top when it hes
partially fallen, and as the sun shines over
one half of the earth in the passage of the
latter around that luminary, the sun light
one portion of the year extends 234 de-
grees beyond one pole or extremity of the
axis, and at another period like distance
beyond the other pole, leaving the former
without the benefit of either heat or light.


The longer the day or the greater the
length of time any part of the earth's sur
face is exposed to the sun, the more it
will be heated and the temperature higher.
Hence it is that the weather is usually
warmest when the days arc of the greatest
length and coldest when long nights inter-
vene.


On some of the planets, as Jupiter, the
variation in the length of the days is small.
The axis being inclined but about. three
degrees, the breadth of his torrid zone is
but little more than six, and consequent
ly the difference in the temperature which
prevails at the polls and at the equator Of
that planet must be much greater than
usually occurs on the earth.


But while the change of seasons is due
to the passage Of the earth around the sun
with its axis inclined to the plane of its
orbit, there are many things on the sur.
face of this planet which tend to moderate
the rigor of cold and intensity of heat.
The direction of ranges of mountains, the
vicinity of large bodies of water, vast areas
covered with timber, high attitudes above
the level of the ocean, all tend to modify the
temperature of the seasons. To these may
be added, as far as northern portions of
the earth are concerned, those rivers in
the ocean, the Gulf Stream, and the warm
stream of the Pacific, called the river of
Japan-the Gulf Stream giving higher
temperature to the northern part of Eu-
rope, and the latter to those portions of
North America which border on the Pa
cifc.


The climate in that strip of the North
American continent which lies between the
Allegheny range and the Atlantic Ocean is
due in great measure to that large body
Of water and that mountain chain. The
direction of prevailing winds is the same
as the direction of the Alleghenies, while
clouds loaded with moisture and long con-
tinued rain are brought by breezes from
the Atlantic. In that bosom of North
America, bounded on one side by the AL,
legheny and on the otker by the Rocky
Mountains, other causes than those which
operate on the eastern slope arise to mod
ify the climate In winter cold winds
from the ice-bound lakes sweep with un-
interrupted force over the immense prai
ries, often accompanied by vast quantities
of snow, while in summer the clouds of
vapor which arise from the waters of the
Gulf are frequently deprived of their
moisture before they reach the central
parts of the valleys Of the Missouri and
the Mississippi Many portions, therefore,
must always be exposed, as the records of
the weather show, to severe storms and
long periods of drought, Climate is a
subject on which much has been written,
and in respectto which much is unknown,
but it can never be otherwise than inter-
esting, as on it depends the permanent
settlement of large portions of the globe,
tho length of life, the leading pursuits and
the physical and intellectual vigor Of the
family Of man.