The sun. [volume] (New York [N.Y.]) 1833-1916, 1897-01-09
1HE NATURE OF FOGs.
How They Arc Formed. and the Good apt
Harm They DO.

harm Ahey no.
Prom Harper's Maoa.fre.
Fog may form In at least three diGeivrS
wayss first. where the AIR is cooled by rapid
radiation; second. where the cooling results
from o mixture Of different air currents. and
third. whore . cooling has been caused by an
uplifting Of the air. The first is the most COM
mon cause-of fox. Radiation fog Ia generally
formed over surfaces nearly level. when warm
air comes in contact with cold ground.
Ssa fogs occur when there is a marked diff
ference between the temperatures OF tile water
and air. or when two:water currents of differ
ent temperature are contiguous. Coast fogs
are formed whom i%nfowing moist air from the
ally are formed at sea during the prevalence Of
some great area u high pressure. or "~anti-cy-
are carried iuisnd. dissoiv:ne as they 20.
IL must DO remembered that the atmosphere
is something like n great gaseous sponge. Com
preston and expansion are constantly going
ON, with resulting cloudy and clear skies and diff
ferent temperatures for various layers. some
the anti-cyclonic conditions illustrate this eI.
cellently.
large hill or mountain It is colder than at the
top. Tho air Is often twenty or thirty degrees
warmer on the SUBMITS than in the Valleys
for days are due To such temperature inver-
sions. On the Pacific coast IL is easy TO trace
high" area and the fog.
Prof. Davi, tells of somewhat similar coudi
tiops In December. 1879. when the lowlands
OF Europ~ we're shrouded in fog Cor most OF
tae month. while in the mountains II was clear
and mild and over twenty degrees warmer than
the sea of fog. AMI the hills piercing throu IN
werc like islands in their isolation.
p%erature inversions and the foss which some,
times accompany them. Fruit and vegetables
IN the valleys are frOst-bitteD. while on the
Nature provides in tho blanket OF . fog
means Of preventing the extreme low tempera-
than q century ago Thomas Jefferson. who APP
pears to have been the FIRST TO notice these pc
sulisrities Of frost, wrote; ~ have known
about Monticello. and vet not injure the tsn-
der fruit blossoms then In bloom on the top and
course OF forty years. during which il has been
settled. there have been but two instances OF .
SSs1ent county eSss py tho is'i fruit Ghi II has sa escaped lp an but s,r , iSte.
In the last seven years"
In California last year a large amount OF
building" metSods.' Mr.. ". II. Hammon 0 e
the United States Weather Bureau pointed out
preventing frost. First. by diminishine me
radiation; second. by increasing the .moisturs
cold air actually draining IL of: and Nth. BY
mixing the air and removing the cold air from
.SmudGe fire. are based upon the nrst meth
cd, and are fairly effective; hut the great im-
pToNemeut conslsts IN the INTRODUCTION OF large
amounts of moisture In tho vaporous state.
When this yapor condcnses. or. in other words,
heat Is given of. hut generally at the very
height At which IL is most needed. Fog and
frost both occur when the skies are clear and
thoroughly mixes tho air that there is little
chance for cold. dry air to settle In the hollows
and low places.
Fog. thsn. as the natural'preventive Of fro,t,
may be a blessing to the orchardist; but there
are others. particularly travellers. TO whom the
YlV can IN = SEnFCA nj annnyAnra and hAnyA
For example, on Dec. II and IL. 1895. an area
of high pressure lay OF the middle Atlantic
coast. Al New York such Q dense fog pre-
vailed over the rivers and bay that the Sound
steamers did not attempt to pass through Hell
Gate. and tho ocean steamships werc all de-
tanned below quarantine. or course there
wero numerous accidents.