New-York tribune., 1901-11-24
FOG LORE AND PROBLEMS
LONDON WILL PAY FOR A NEW IN
VEsTIGATION-THE DEsIRABIIITY
OF FORECASTING FOGS.

learned concerning them. And while the in
convenience experienced from this cause during
the last few weeks may not have been much
greater than usual 1t has led to a provision for
a fresh investigation of the subject under COM
bined local and national auspices. The County
Council supplies the money, and the Meteoro-
logical Council selects the experts required for
the undertaking.
The chief aim of the inquiry is highly prac-
teal one, and suggested ty the local cleo
trio and gas light companies The hopelessness
of preventing fogs is generally conceded
that Englishman considers that possi-
bility for moment. But if the occurrence of
this nuisance could be foresaen even by two
three hours, it would enable the corporations
which supply London with artificial illumination
better to meet the extra demands put upon
them. Hence the meteorological experts who
are about to wrestle with the subject VIII
be asked to say. first of ALL whether it is prac-
ticable to forecast fogs or not. But, incidental
ly, of course and perhaps as a necessary pral-
ude to answering that question, they will doubt
less give much attention to the conditions under
Y hich the phenomenon occurs
These already known to be somewhat
various. though the immediate cause is tech
nically the same Fog like cloud and frost.
is a condensation OF previously invisible moist
mosphere the more vapor it will hold Hence
a lowering Of the temperature without any
alteration of its absolute humidity will bring
the air closer and closer to the state of satura-
ton, and any chilling beyond that limit. which
is called the dew point will compel the air
to give up a portion Of its watery contents.
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 tha
warm Gulf Stream in the Atlantic drifts north
ward and encounters the cold Arctic current Z
the Newfoundland banks. it experiences a ~
ducton Of temperature below the dew point au3
fog results. The same thing comes about wh.-
warm sea air enyelops an iceberg. or flows
gently inland over region covered with sno9>
or much colder than the ocean. This latter stu
alton 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 the rapid radiation Of The
earths heat reduces the temperature Of the al,
close to tho ground several degrees below thai
at elevation OF only few feet Valley fog
are produced under substantially the same con-
dltious And while a fog bank usually lies at a
low level. and often rests upon the earth sea
II sometimes exists at an appreciable elevation
chilling from above rather than from below.
the particular stratum Of the atmosphere in
which il occurs.
\ 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 more instruct
i've To discover if possible, the method by which
he chilling IS produced. And this research may
need To be broad enough TO cover air tempera-
.ures at considerable heights. Balloon and kite
show that the rate at which tenn
oerature falls with elevation above the earth
n that irregularity hidden meteorological
secrets of great Importance Already the Amer
can Government and private meteorologtsts.
ike Mr. Rotch and his assistants. have explored
he upper air with kindred objects in view. but
lot especially for the purpose of forecasting fog
Whether this procedure would be Of value Il
.ondon can be determined, perhaps. only by ex-
pertinent.
one step in the inquiry about 10 be conducted
II t,neland will be to organize a staff of Volun-
eer Observers to report conditions eXistln4
simultaneously over considerable area Proha-
,ly all the fire stations in London Will he in
Iuded in the system. The national Weather
3uraau VIII furnish the necessary instruments
nd draw up the code of instructions When a
ufficient amount of data has accumulated the
,oyern1nent experts Will review and digest it for
PRACTICAL. purposes