Daily globe. [volume] (St. Paul, Minn.) 1878-1884, 1882-10-13
What are Clouds2

What are Clouds?
Though the clouds are such familia,
objects, very little is known about them
and the processes by which they are
formed and give back their moisture tc
the earth are unsolved mysteries.
They cannot be classified as belonging
to the solid, fluid, or gaseous form o!
matter. Yet they are defined as being
"a collection of watery particles in the
state OF vapor, suspended in the air. >
1t they are ordinary vapor, they must
be governed by the laws which effect
vapors. Brande defines vapor thus
'When liquids and certain solids are
heated, they become converted into
elastic fluids or vapors, which differ
rom gases in this respect, that they are
not under common circumstances per-
manently elastic, but resume the liquid
. or solid form when cooled down to ordi-
nary temperature. According to this
definition, clouds cannot be composed
OF ordinary vapor, for under all condit-
ions their temperature must be below
the condensing point of water-vapor.
At tho elevations at which clouds are
often seen, they are in the regions of
perpetual congelation; and as they float
| above the highest mountains they must
be exposed, even in the sunshine, AMI
| certainly in the night, when the solar
heat is not poured upon them, to tenn
peratures colder than those of the frigid
zones.
As they occur in all climates, over the
poles as well as the equator, and even
in the warm ATTITUDES at elevations
which are above the regions of unmelted
SHOWS, it must be assumed that low
temperature alone does not cause them
to give up their moisture in the form OF
rain or snow.
Glaisher, in entering cloud eleven
hundred feet thick, found the dew-point
remained unchanged, showing that there
was no more (condensable) moisture in
the cloud than in the surrounding air.
And eronauts obtain no dew by Reg
nault's hygrometer at an elevation of
Eve miles, but clouds float above that
height.
The moisture in the air must not be
confounded with the water of the clouds.
This moisture is precipitated by low
ton of water on the outside of glass of
ice-water on a warm day, and the coat
ing of the inside of window-panes with
les on very cold one; and the formation
of dews in summer and of frosts in
winter.
The precipitation of the moisture from
the clouds must be caused by some Pc
culiar condition Of the clouds them
selves. After rain there often are as
many clouds remaining or passing away
as there were at the commencement Of
or at any time during the rain. In this
there is evidence that the action going
on in part of a single cloud, or in spe-
cial clouds, does not extend over the
whole mass, nor to other clouds near
by.
In countries where it seldom, or never
rains, or where the rains are periodic.
clouds are as common as in places where
it rains often. From this it appears that
the causes which produce precipitation
are entirely suspended, or rather do not
exist in certain localities and seasons.
although clouds abound there at the
time.
Another fact worthy of consideration
is that snow and rain fall slowly, little
by little, and not in one sudden down.
pour, as would be the case If the whole
mass of cloud or clouds were brought at
the same instant under the action which
produces rain or snow.
It must not be forgotten that clouds
move in well-defned masses, sometimes
retaining their shape for long time,
and do not disappear in the air, as they
would do if they were ordinary water
vapor.
As it is difficult to reach the clouds.
little has been learned of their ccmpos-
ition. But at the elevated stations of
the meteorological departments of the
various nations where the observers are
at times in the m;dts of clouds, oppor-
tunities may occur for observation and
examination of them, which will reveal
the laws by which they are governed.
It is not too much to expect that the
acute and practical minds of the present
age will, ere long, add much to our
present scant knowledge of these mys-
FERROUS meteors.
@. MoRPT.
Popular Science Monthly.