The National tribune. [volume] (Washington, D.C.) 1877-1917, 1890-09-04
THE WEATHER.
Cloud Observations.
ny LIEUT.. J. p. FINLEY. U. e. SIGNAL SERVICE.

ny LIEUT.. J. p. FINLEY, U. g. SIGNAL SERVICE.
No kind Of meteorological observation Is OF
moro importance than that Of the forms and
movements Of the clouds; but IL requires some
study aud experience 10 know how and what
10 observe, and unfortunately there Is no class
Of ob3ervatioual work that has received less
satisfactory attention. Clouds afford us the
only information we can obtain of the changes
in progress in any part of the atmosphere
above the very lowest stratum for it is only
that stratum which rests Immediately on the
carth'a surface that we can probe aud analyzo,
aud whose motions aud conditions we can study
by means OF the instruments usually employed
in meteorological work.
In the first place, tho very existence Of q
cloud Mt any elevation is an indication that the
atmosphere is there In u state of saturation
and the lower tho cloud, the more humid, rela-
lively, il the atmosphere. In the second place
the forms of tho clouds may give information
as 70 the changes Of temperature and tho cause
OF these changes; and, thirdly, their movements
show what winds are blowing high up In the
atmosphere, and even tho rate of their move
mcnt
If indeed tho hight Of the clouds Is meas.
ured they serve both AS a wind vane and ane-
mometer whose precision leaves little TO desire
Cloud observations, as usually made, include
their quantity, form and movement. The pro-
portion OF the sky covered by clouds is esti-
mated by simple inspection. A sky wholly
overcast Is recorded as |" 10" of cloud and all
minor degrees of cloudness by the lower mum
bcrs, the figure cor being used TO indicate an
uncl0uded sky. From the nature of the obser-
vation an approx innate estimate only is posi-
bic, but with a little practice, it will DO found
easy 10 make 10 with sufficient accuracy for
practical requirements.
1t may assist beginners in making this esti-
mate 10 notice that, If the sky be supposed d-
vided in 10 five triangular scgments by five equi-
distant lines drawn from the zenith 20 the hori-
zOn, each Of those will be divided into two nearly
equal parts by line parallel with the horizon,
aud at one-thrd the distance between it and
tho zenith. In making the estimate, clouds at
great distance, low and near the horizon,
should not be regarded, as tho optical effect
under such circumstances is likely to prevent
accurate observation
1t is usual in meteorological trcatses and
| record registers to adopt Luke Towards CLASH
| fcatiOn OF clouds, but as POey. Frtsch, aud
| DIR. Mann have pointed out, much confusion
| has arisen III the application of Towards ter
min0logy, partly owing to defects in the orgi-
nal definitions, and partly TO the msconcep-
| tons of those who have adopted his system.
| In no case Is this confusion more apparent than
in the application Of the term stratus. Towards
| stratus cloud Is simply fog, whether resting on
bhS BiphhN Va ~ hOLlo NSiJ SlhalI ulRuL hUuNG
| it, But, misled by the pictorial representa-
tlons given in illustration of tho type, it is a
common practice Of observers toenter AS stratus
all clouds which appear as horizontal streaks
near the horizon, and which being really
| high IN the atmosphere are generally GIRO
| stratus. Stratus Is an unusual cloud iii many
| parts of the world, especially in regions with a
low humidity. In damp countries IL is more
common because the conditions of moisture ARE
present which give rise to it's formation. Many
| OF the objections TO Towards classification
have been removed by Poey, who, retaining
certain features, has reclassihed others, without
sacrificing the simplicity, but, on the contrary
adding to both the simplicity and definition Of
the system. Poeys classification Is as follows
], Cirrus; 2, cirrO-stratus; 8, cirro,cumulus
4, pallium; s, pallio.cirrus; q, pallio-cumnlus
7, cumuius; q, ractO.cumulus. Of these the
first three aud 18th are the higher clouds. The
last three arc the clouds Of the lower atmos
| pierre