Year: 1865

Why are highlands in hilly country more
and fall less exposed " frost? Thus asks
Pennsy 'VsniA correspondent.


Snow occurs earlier in the fall and continues
later in the spring, on high mountains, than on
lower hills and in the valleys. Ia Now Eogland
we ever hear Of the early snow on the summit
Of the White Mountains, and on tho higher
tops Of the Green Mountains or, on the SUM-
mits Of the high peaks in the northern part oil
the State Of New York, or the like places in
the Allegheny range, than on the low grounds
contiguous to these mountains. This takes place
earlier in the fall the further north and higher
the mountain summit. The atmosphere is thus
proved to be colder as the place is higher. For
about each five hundred feet OF elevation, In the
same circumstances, the temperature is one de-
gree lower. This Ii true, also, as we ascend in
balloon into the upper regions. Thus, too, we
often see snow falling from clouds, which il
melted before it reaches the earth. la hilly
countries the snow is often eeen TO cover the
hilltops and down their sldes to three or four
hundred feet above the adjacent valley, from
which point only rain fell III the valley, and the
line Of snow can be distinctly seen for miles
horizontally along the side Of the hills. On
very high mountains, even near the equator, the
snow line in summer is far below their submits
| The tropical sun Of summer does not prevent
the line OF perpetual congelatlon from remain.
ing, though the line is higher on the Himalayas
lower on the Andes, and lower still on the Alps
and on the Rocky Mountains.


The second question is easily answered, also
| have known Indian corn killed by the frost u
September in valley, while on the hills, few
hundred feet above, no frost was formed
once saw the common flowers OF many garden,
killed by the frat frost Of autumn, while a gar
den perhaps three hundred feet higher, and fully
exposed, flowers OF the same kind were moi
touched by frost. as particular examination Of
them proved none had formed there.


Dew and frost are formed only in clear and
still nights Then, plants, water, earth, having
been more heated by day, and having impaired
of their heat to the atmosphere in contact,
throw off their csloric by radlating it into and
through the air, become colder, and cool the air
| in contact with them, until dew is formed, or
even frost, II the process Is carried sufficiently
| far. At the same time the warmer air of the
valley, above the plants, rises and the cold and
heavier air OF the hills settles into the valleys,
and when the valley is not wide this effect aids
in increasing the cold and frost. In such deep
valley US Franconia, n. H., in the midst Of
mountains, the great cold is thus produced
But on the moderate hills, the radiation IS less,
the cooled air, too, settles toward the valleys,
and often perceptible current Of air is formed
which eiIectualy prevents the formation OF
frost.


In the spring the same causes operate in the
same way. But as the climate is cooler on the
hills, vegetation is later, and the flowers Of the
apple, or peach, which may be killed by frost
in the valley, are not sufficiently advanced to
suffer injury on the hills or, when they come
TO be exposed, the increased heat Of the season
may prevent the frost ON the bills. Should this
last not prove to be a fact, the flowers on those
hills will be destroyed at a later day, when those
ol the valley have passed the danger.


There may be local causes which operate to
prevent the evils OF the frost. Thus, along the
south shore of Lake Ontario there is fne fruit
bearing country lor ten or twelve miles from the
lake. Very rarely are the blossoms OF the peach
killed by frost in this district, as the vapor ris-
ing from the lake is converted into hazy clouds,
and no frost is formed. few more miles at
the south the sky remains clear, and the bios
SONS are frozen.-Moors's Rural New Yorker.