FLORIDA STATE HORTICULTURAL SOCIETY. 
155 
states and was rapidly settling southward 
along the eastern slope of the Rocky 
Mountains. 
The pressure was 31.42 inches at Can¬ 
adian stations with isotherms of zero and 
minus 10 overlying Northern Texas. A 
temperature of minus (—)4o degrees ob¬ 
tained along the northwest boundary. By 
the morning of the 12th the isotherm of 
10 degrees had reached the west gulf, and 
on the morning of the 13th it was felt at 
all South Atlantic and gulf stations. On 
the nth there appeared a feeble storm 
center in the gulf, which rapidly devel¬ 
oped into a storm of great intensity and 
which augmented the severity of the al¬ 
ready highly energized cold wave, giving 
the lowest temperature on record over the 
South and Southwest. 
HOW COLD WAVES TRAVEL. 
Several essential conditions must be 
fulfilled that a cold wave retain its for¬ 
mation and reach the Atlantic Seaboard 
with a reasonable share of energy. “A 
necessary condition,” says Prof. Garriott, 
“to the southward sweep of a cold wave 
is an unbroken area of high pressure ex¬ 
tending over the Rocky Mountains and 
plateau region.” This may be supplemen¬ 
ted by the observation that an active cy¬ 
clone, usually an accompaniment, to the 
south and east drawing down by vertical 
action the cold, dense air of elevation, in¬ 
sures the continuation of the cold wave 
beyond our field of observation. 
The low area storm being propelled 
eastward as an eddy in the atmospheric 
world marks out with almost unfailing 
accuracy the section where temperature 
will be lowest. Most of the cold waves 
move east over one of the northern cir¬ 
cuits, and for this reason their severity 
is not felt to any great extent south of 
the central valleys. 
Those that take the southern circuit, 
however, overspread the greater portion 
of the country east of the Rocky Moun¬ 
tains; and the resulting damage depends 
on the aera covered by them, which fre¬ 
quently exceeds 2,000 miles. 
The cold, dry air flowing off in all di¬ 
rections during a cold wave is not alone 
due to the temperature of the sub-Arctic 
regions translated south and east by the 
general circulation equally to, but the 
vertical action that is going on within the 
great anti-cyclone; a process whereby the 
cold of the upper air levels is brought 
down, proving a potent factor in aug¬ 
menting the cold condition of the lower 
strata. 
A 
FEBRUARY THE COLDEST. 
Cold waves are most frequent during 
January, the culmination of winter con¬ 
ditions, although the most disastrous ones 
in the Southern States during recent 
years, occurred in February. The great 
damage in Florida, at Gulf or South At¬ 
lantic stations during February results 
from the advanced condition of fruits and 
vegetables. By that time crop growth 
has been stimulated by several weeks of 
warm weather. The orange shows bloom 
and the tomato, bean, celery, cabbage and 
other succulent plants are susceptible of 
great damage. Several cold waves in the 
Southern states have been more frequent 
during the past two decades than during 
the previous half-century. The earliest 
cold wave in Florida that caused lasting 
