Evening star. [volume] (Washington, D.C.) 1854-1972, 1895-08-30


predictions, and I will give brief state
ment of what believe to be original ideas
introduced into the making Of frost fore
casts while in charge OF the Wisconsin
state weather service, a state including
within its domain the largest area of cram
berry marshes in the world and also in
GLIDING an extensive area devoted to the
cultivation of tobacco. Heretofore 1 believe
that only the air conditions have been
taken into consideration in the making of
frost forecasts-such as pressure, tenn
perature, relative humility cloudiness and
wind velocity. AS result, of my inyesti-
cations, Systematically prosecuted for three
years, I found that the condition Of the
soil was equally as important as those of
the air. al VI,
when the high pressure area is moving
in from the west, clear and colder weather
anticipated, with the probability that the
early morning temperature will permit the
formation of frost, the most important
elements to be considered in the deter
mining whether or not frost will occur
injurious to growing crops are as follows:
First. Has rain recently fallen and what
is the condition of the soil relative to the
amount of moisture CONTAINED?
Second. What are the natural properties
of the soil relative to the slow or rapid
loss of heat by radiation?
Third. To what degree of heat has vege-
tation been subjected during the period i'm
mediately previous?
Prevention of Frost Damage.
1.-The early fall frost injurious to tender
crops is the one which occurs with the town
or Geographic minimum temperature, rang
ing from forty to fifty degrees. Because
when the early morning temperature in the
town falls to nearly the freezing point it
is usually SO late in the season that all
crops are gathered, or II not gathered
they have been destroyed ere this condition
arrives At the time, then. that frost warn
ings are of benefit we have to deal with the
air considerably above the freezing point,
and to receive deposit Of frost 1t Is neces-
sary that the temperature of the top soil
freezing point. This, of course, is accom-
plished by conduction and radiation of
heat, which takes place more rapidly from
the soil and vegetation than it does from
the lower stratum of air 10 the higher.
Anything that will seriously interfere
with rapid loss Of heat after nightfall
will tend to prevent the formation of
frcst. Moisture does this, and If the soil
be well charged it partakes greatly of the
stable temperature condition of water and
cools but little, If any, below the tempera-
ture Of the superintendent air, and no
frost will occur even though all other con-
GitionS of clearneSS, gentle winds and cool
air obtain. Even a small amount of moist
ure, say one-half inch Of rainfall, will
give ample protection If well distributed
ard precipitated within the twenty-four
conditions are prevalent Injurious frosts
may occur when the Geographic tempera-
lures do not show a reading within ten
degrees as lew as in the first case.
How to Improve the Forecasts.
II believe that when estimating the prob
ability or severity OF frost sufficient weight
has not been given to the dryness or wet
ness of the soil, and the resultant dissi-
patton or conservation Of heat energy, and
til ~.,,k
of the means for improving the forecast.
Il have in mind two typical cases. In
tho first high pressure area attended by
clear and cool weather drifted from the
westward until it covered the state and no
rain fell with the passage of the low pres
sure area Immediately preceding it. Hence,
the ground was in excellent condition for
the rapid loss Of heat during the night
and consequent lowering of the tempera-
ture Of vegetation to the freezing point.
Considerable damage was done to cranber-
ries in unflooded marshes. In the second
case a high pressure area Of slightly greater
weight and slightly lower temperature
covered the region about ten days later,
but 1t was preceded within Ia few hours by
light but well-distributed fall of rain,
averaging about one-half an inch, and no
frost occurred In both cases the wind
was gentle from the northwest, and the
nights were clear With slightly lower air
temperature and higher barometer in the
second condition, heavier frost would have
occurred than in the preceding case had
it not been for the thinly spread moisture
of the timely rain conserving heat at the
surface of the earth. r.
Some Strikinsly Original Suggestions
might not this principle be carried fur
Their in the improvement Of the forecast?
Assuming that the calorice energy of the
sun is a constant factor, the earth receives
each year the same amountIor intensity of
heat, and as the atmosphere is warmed
mainly by contact with or radiation from
the earth, seasonal variations of tempera-
ture, which are marked departures from
the normal, might result from abnormal
terrestrial surface conditions with respect
to the conservation of this constant solar
energy over large continental areas. Here
the excessive or deficient rain fall during
the preceding seasons should receive care
full consideration. The subject is one that
requires deeper and more detailed invest1-'
cation than the length of this paper will
permit.
Il find that the minimum temperatures
in cranberry marshes during abnormally
dry seasons often fall fifteen degrees below
the temperatures telegraphed from the
cities and towns within a few miles Of the
marshes. This is due to the fact that
WREN the loose, spongy peat Of which the
marsh is composed to the depth Of several
feet has dried out the radiation of heat
during the night was very rapid and the