Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1882-02-08
DEW POINT, HIGH WINDS AID WEATHER.

Sergeant Barwick makes the following
statement upon the above subject. in addi-
ton to that heretef re published In .nese
columns Having had numerous questions
propounded to ne regarding the de" point.
etc. since my article first appeared IN the
REooRD UNION, short time ago, con-
cluaed 70 exolain it more thoroughly, and
give my reasons why colder weather with
northerly winds does not produce injurious
frosts Ike a less colder temperature with
moist portherly wind.
Professor Eias Loomis, of Yale College,
the best meteorological authority in this
country in defining the dew point says
The amount of vapor Ia the air may be
measured with great accuracy by noting the
temperature at which moisture begins to be
condensed on a cold vessel. The moisture
then deposited is called dew, and the tenn
perature az which ills deposition be-
gins Is called the dear point. The
dew point. then. may always be
determined by cooling metallic vessel until
dew begins to appear upon its surface. and
noting By 8 thermometer the temperature OF
the vessel" Dsw or frost cannot be deposited
until the temperature CT all substances ex-
posed 60 the radiation Of clear sky is cold
enough to reduce the temperature OF the air
il contact with it to that point at which dew
or frost is formed that point is variable
one, being governed by the amount OF moist
ure in the sir. For example, on the morning
of the I'd instant there was killing frost.
with light breezs blowing from the south
temperature of the air, 80 deg; dew point,
81 deg. On the morning of the Sd there was
another killing frost, with gentle breeze
blowing from the north (; temperature OF the
- i TIT 1aO On fha
morning of the 7th, very light frost, after
the heavy blow from the north the temper
ature Of the air was SO deg; dew point "A deg.
Now tire careful and observant reader will see
that on the % and Sd the temperature OF any
substance would have to be reduced only 8
below the temperature Of the air before
moisture would be condensed upon it. While
on the morning OF the 18th the temperature OF
any objects would have to bs reduced II be-
fore the slightest moisture would be deposited
on them. Now isn't it plain to be seen, ald
hope easily understood, that greater
amount Of cold can be endured by growing
substances, without being injured by frost.
with our northeEly winds, than could be
sustained by the same growth with
soptherlv or more moist wind, because the
dew poiat Of the south wind is so much
nearer the temperature Of the sir that objects
on the earth's service are more easily and
quickly reduced to that temperature which
would coudense the moisture in the air coming
in contac. with them, while the air brought
With the north wind requires to be reduced to
much colder temperature before dew or
hoar-frost Would be deposited. The tempera.
ture Of plants on the 7th could have stood
temperature of 25'. and there would have
bean no frost deposited, while the tempera-
ture Of plants, grass, etc., on the p aud 81
would have been covered with very heavy
and killing frost if their temperature had been
reduced to go or 30', or evan 800. Therefore,
on the 81, instead Of moisture being dspos-
tied upon grass, ETC., By the north winds, the
moisture would be absorbed or evaporated
from them. the wind-atorm which ended at
SP. N. of the Oh, after thirty,swo hours
blow, amounted to 5I2 miles. or en- average
OF 16 miles per hour. The highest velocity
occurred st 1:30 P. NJ. on the 9Th, when it
reached SO miles per hour.