702 MONTHLY WEATHER REVIEW. O~OBEB, 1919
The eneral opinion is that winter ains should be
when freezing and thawing conditions prevail. .i;he re-
e u l h of studies in Ohio by the writer and by students taking the advanced course in Agricultural 3feteorology
at the Ohio State University show little to substantiate this opinion, at least during part of the winter. A correlation between the number of da-ys with snow on the round from December to March, inclusive, and
cient of only -0.14, f0.14. A correlation between the yield of wheat and the number of days in March with beezing weather, while t,he ground was bare, gave a coefficient of only -0.01. A correlation of the yield with the number of days during the whole winter with the ound bare and the toniperature below POo pro-
slight relation, but the others indicate no real effect of the lack of a snow coveriw on the yield. In the spring of 1915 1%. Harry Roads made a cor- relation between the nuniber of day3 with freezin and thawing weather during the whole winter in C!kiton County, Ohio, and the yield of wheat, and got a cor- relation coefficient of only -0.18, or less than two times the robable error. The period covered was 28 years. into account, but a8
this county is in southern Ohio x e r e there is generally eat amount of snow-coverina it shows that freezing an thawing conditions do not Rare so eat an effect upon the yield of wheat as has been thoug t. On the other hand, there is some evidence to indicate that wheat has a better
without a snou--
covere d by snow during cold weather anrmore es ecially
the yiel 8 of wheat in Fulton County, Ohio, gave a coeffi-
duce !f a coefficient of -0 .3 , f0.14. The last gives a
He a id not take the snow coveri
nof %
is not covered by A correlation by
K
Table 1 showed that a heavy snowfall in Januar somewhat beneficial, while the above indicates t at a
snow-covering in that month may be detrimental. The ex lanation may be that a heavy snodall in January
while the vound is bare in this month, disintegrates the soil particTes and settles the earth around the dormant root,s and makes the plants better able to withstand later unfavorable conditions when they begin to develop. Heaving is one of the most coninion causes of damage which usually occurs in the spring and is due to alternate freezing ani1 thawing. It is possible, also, that a heavy snow-cover in January produces Conditions favorable for smothering the gain, either froin a very deep accumu- lation of snow, or, what is niost coninion, the formation of an ice sheet froin the partially meltod snow. The whole subject of winter damage to grains whether by heaving, smothering, freezing of plants, or physiologi- cal drought, and t.he part that a snow-cover or lack of it, plays is worthy of a most thorough study. The facts aiven above, although based on too little data, nia in- h a t e the direction that. the investigation should tale.
me ? ting quickly, as well as freezing and thawing weather
PROTECTIVE POWER OF SNOW.
The following observation [at Falling Royd Hebdcn Bridge, Yorkshire, England] shows the remarkable ex- tent to which a covering of mow rotects the ground
13th of January a minimum thermometer was placed on
the ground in the center of my lawn here, the tem ra- ture then being only a few degrees below freezing. g o w then fell to the depth of 13 inches. A t 11 p. m. the snow had ceased falling, and i t was a bright starlight night and very cold. A second minimum thermometer was then placed on the top of the snow. No more snow fell in the night. In the morning the two thermometers recorded the following minimum temperatures: On the top of the snow, 2 F. below zero; mider the snow, 24
F., or a difference of 26 de-gwes.
A . R. &OSSzCy (in Symonem Meteorological Mag., Feb., 1918,53:20).
and plant life from intense cold. A R out 6 p. m. on the