The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1895-11-01
THOSE FOES THAT MAY CO,
They Ride Over the City on the
Dirt That Floats in
the Air.
We Get "Scotch Mists" Once in a
Great While, and They Are
Clean, Wet Fogs.

The possibility of keeping securely at
bay the fogs that roll over San Francisco
from the ocean by establishing a battery
Of lightning machines along the coast, as
described in Wednesdays CALL, on the
authority of Professor McAdie of the
Weather Bureau, was reflected on and dis
cussed theoretically by many physicians
and others yesterday.
The idea that man can here, on and about
this narrow peninsula create an artificial
climate by changing the very course of
nature is rather a startling one when
first received but Mr.. McAdie shows that
the possibility is scientifically demon
strated.
Add to the removal of fogs the cleansing
of the atmosphere of the smoke, dust, dis
ease germs and other impurities that float
thiCkly in it, inhaled with every breath,
| and almost daily obscuring the bay and
hills with soft haze, and we have city
enjoying a climate unequaled on earth.
These possibilities of aerial sanitation
and fog dissipation which may be referred
to the coming century for definite discus
! sion bring into view the fact that there IS
| big lot that isn't known about these same
| fogs. Nobody knows with any approach
| to correctness how much fog San Fran
cisco gets, for one thing. The only fog
| records In this City that are in existence
| are at the Weather Bureau, and there has
| never been any requirement, reason or
want that would lead the bureau to COM
pile fog records with much particularly.
Forecast Official Harmon explained
yesterday that the compiled records show
the numb Der of toggy days at this as well as
at all other weather stations, but the
number OF toggy days doesn't mean very
much. A "foggy day" according to the
Government weather service is day when
fDro 10. i
1000 feet from the observing station.
From my own observations" said Mr..
| Harmon yesterday, "since I have been
here l know that the heaviest logs and
their greatest prevalency exist during the
months of June. July and August"
More definite fog information will likely
be among the things that will result from
the greatly expanded studies of Pacific
meteorology instituted by Mr.. Harmon
some time ago and from the new investi-
| cations to result from the coming of Mr..
McAdie as assistant to Mr.. Harmon.
1t transpired yesterday during talk
with Messrs. Harmon and McAdie, up on
the tenth floor of the Mills building, that
| some OF our fogs are not fogs. Once in a
while we have ''Scotch mist" about four
| or five times year, Mr.. Harmon says.
The main difference between fog and a
Scotch mist is that one is dirty and the
other is clean. There is surprising
amount OF theory yet ABOUT simple meteor
illogical things, and one thing pretty we'll
backed up with scientific demonstration is
that fogs, and clouds, too, are largely
! formed by the collection of moisture
around little particles floating in the air.
In the case of fog, when air saturated with
moisture IS squeezed by lowering in
| temperature the condensed moisture col
lects about the infinitesimal particles of
solid matter floating in great quantity in
the air, each one of which becomes the
nucleus of fog globule. Scotch mist is a
| condensation into infiniteslmal particles of
| watery vapor, which do not have their
nucleus. Scotch mist is finer than fog and
wetter. That fog is moisture clothed i'm
purity is one reason why 1T is so readily
dissipated by electrical discharges.
| Along with the amount, distribution and
nature of San Francisco fogs there remain
some things to be known concerning the
making of them. The upper air, which
the weather service is now getting ready to
investigate, probably has something to do
with them. Some of the explanations are
yet theory.
1--WE get more fog here in San Francisco
than other places on the California coast"
says Mr.. Harmon, because we are in the
| gap OF the coast mountains between the
ocean and the interior basins, and the air
currents are drawn through, bringing the
fogs with them. It's like being in the
neck of a bottle. The fogs are brought
In several ways. In all cases the primary
principle, of course, is the cooling of air
! saturated h CIV