Milford chronicle., 1903-01-30
FOG LORE AND PROBLEMS.
london Is Going to Pay For a New
Expert Investigation.

Although the metropolis of the world
has suffered from fogs from time imrle-
mortal. her wise men recognize that there
is much yet TO be learned concerning
them. And while the Inconvenience expe-
rienced from this cause during the last
few weeks may not have been much
! greater than usEal. il has les to a pro
vision for fresh investigation of the sub
/ ject under combined local and national
/ auspices. The county council supplies the
money and the meteorological council Sc
/ lects the experts required for the under
taking
The chief aim Of the inquiry is a highly
practical one and was suggested by the
local electric and gaslight companies.
The hopelessness Of preventing fogs is so
generally conceded that no sane English
man considers that possibility for a mo-
ment But if the occIrrcnce Of this ni;i-
sance could be fOreseen, even by two or
three hours, it would enable the corpora
tions which supply London with artificial
illumination better to meet the extra de-
mandS put upon them. Hence the mete-
geological experts who are now about to
wrestle with the subject will be asked to
say. first Of all. whether it is practicable
to forecast fogs or not.
But incidentally. Of course. and per-
haps as necessary prelude to answering
that question, they will doubtless give
much attention to the conditions under
which the phenomenon occurs.
These are already known to be some
what various, though the immediate
cause is technically the same. Fog. like
cloud and frost, is a condensation of pre-
viousy invisible moisture suspended in
the air. The warmer the atmosphere the
more vapor it will hold. Hence a lower
ing Of the temperature without any al
teratiOn of its absolute humidity viii
bring the air closer and closer to the state
of satGraton. and any chilling beyond
that limit which is called the dew
point will compel the air to give up a
portion of its wateIy contents as cloud or
fog, or else as rain, hail or snow. And
the ways in which this cooling is brought
about are numerous.
When the layer of atmosphere lying
above the warm gulf stream in the Allan.
tic drifts rOrthward and encounters the
cold arctic current at the Newfoundland
banks, it experiences reduction Of tenn
perature below the dew point and fog re- !
suits. The same thing comes about when |
warm seH air envelops an iceberg or flows |
gently inland over a region covered with |
snow or much colder than the ocean |
This latter situation arises frequently in |
winter
But the cooling may also come about |
without even the slightest atmospheric |
movement in a horizontal direction Frost
forms, for instance. in a calm. when tie
rapid radiation of the earih's heat rc-
duces the temperature of the air close to
the ground several degrees below that at
an elevation of only few feet. Valley
fOgS are produced under substantially the
same conditions, And while fog bank
usually lies AT low level and often rests
upon the earth or sea it sometimes exists
at an apprecia5le elevation. The latter
fact would suggest possibilities of chilling
from above rather than from below the
particular stratum of the atmosphere in
which it occurs
A writer in Nature deems it desirable
to ascertain the source from which the
water comes which is found in the form
Of fog. but it would seem to be equally if
not moro instructive to discover. If pOssi-
BILE, the method by which the chilling is
produced. And this research may need
to be broad enough to cover air tempera-
lures at considerable heights. Balloon