NATURE 
Sept. 8, 1870] 
We now proceed to present the basis of a new classification, 
more in harmony with the actual data of the science, and which 
is the fruit of twenty years’ assiduous study upon the clouds, in 
the Antilles, as well as in Mexico, the United States, and 
Europe. From the beginning (at that date) of my meteoro- 
logical studies at Havana, a city situated in the tropics where 
the evseméle of atmospheric phenomena affects an extreme 
simplicity in consequence of their surprising regularity, which 
is effaced as we approach the higher latitudes, ever since, I say, 
I have more and more felt the necessity of reforming Howard’s 
nomenclature. For a long time I was unable to understand the 
four cloud formations, which I had come to reject, namely : 
Stratus, Nimbus, Cumulo-Stratus (different forms of Cumulus), 
and Strato-Cumulus. It was only later that, having been able 
to consult Howard’s original work, I perceived the errors into 
which Kaemtz and all the meteorologists had fallen. I have, 
then, to introduce into Howard’s classification the essential 
modifications which the continued progress of meteorology now 
requires, in order that the nomenclature may be more in har- 
mony with our new conquests. I acknowledge with pleasure 
that Howard’s classification of clouds, which has ruled without a 
rival for more than half a century (A.D. 1802), was originally 
based upon a profound study, directed by great acuteness in 
the observation of facts. But unhappily this is too plainly 
stamped with the locality where Howard’s studies were alone 
prosecuted. Iam speaking of the gray and cloudy sky of 
Great Britain, whence are his S¢a¢o-mis?, his imperfect distinction 
of the two strata Cirrus and Cumulus, or his Nimbus (the rain 
cloud), the difference which he has established between Czmzzlus 
and Cumutlo-stratus, without counting many other details of 
description, which are faulty, in relation to Cirrus, Cirro- 
stratus, and Cirro-cumulus. 
Here is now the vindication of my three new clouds. When 
certain clouds are spread out uniformly, cover the whole face of 
the heavens, take a gray or ash-colour, under which state rain 
may occur for hours and whole days, what name do we give to 
these clouds? They are not Howard’s Mimdus, as we conceive 
them and as they are generally described. These clouds are 
neither stormy, nor have they electrical manifestations, there is 
only a fine and continuous rain. Under this stratum—for it is 
a true stratum—we see constantly other clouds more or less 
considerable, but always isolated, come to be lost in it and to 
increase its thickness. On the contrary, before this stratum 
begins to break up, and during this operation, we see these same 
formless fragments detach themselves and fly to other regions. 
This inferior stratum is not alone, for when its disruption has 
taken place we see through it another stratum of clouds, whiter 
and less dense, which is broken up in its turn, and ends by 
disappearing in an inverse order to that of the first inferior 
stratum. Have wea name for this variety of cloud, so common 
in time of rain from the inter-tropical regions to high latitudes, 
especially in winter, during falls of snow? Does Howard’s 
term Nimbus and his description of it account for this sort of 
cloud? Certainly not. We name indifferently a Mimdus, the 
single storm cloud, as well as this inferior stratum, or yet the 
two united strata, and all this without electrical manifestations. 
This is what I call Peddum; that is to say, those strata of 
which the superior is formed of Czvrus, constitute the Ped/io- 
cirrus and the inferior of Czmudlus constitute the Pallio-cumulus. 
The fragments of clouds which differ entirely from the Cumzlus 
or Cumiulo-stratus are the Fracto-cumulus. 
Hence we see the necessity of distinguishing these two 
strata by different names; Howard’s unique name of Nimbus 
did not do this, while granting him the greatest descriptive 
exactitude, which he is far from possessing. This necessity 
results moreover from the fact that the stratum of Cirrus 
is formed many hours, and even many days, before that of 
Cumulus, especially in the equatorial regions, and in fine that 
the latter disappears first. Without this distinction we are 
obliged to call the first stratum Cévrus and the second Cumulus ; 
but as under this state of strata the form and physical proper- 
ties of Cirrus and Cumulus change completely, there results 
the confusion and errors daily committed. 
As regards Howard’s classification as a whole, while retaining 
the two types of Cirrus and Cumulus, with his two derivative 
clouds, Cirro-stratus and Cirro-cumulus, I reject entirely his 
Stratus, his Nimbus, and his Cumudlo-stratus, together with the 
Strato-cumulus of Kaemtz, for the following reasons: Stra/us, 
because it is not (according to Howard) a cloud properly so- 
called, but a mst or hoar frost, or yet by the effect of an op- 
383 
tical illusion, a Cirrus, a Cirro-stratus, or a Cirro-cumulus, 
as seen in perspective at the horizon; Mimdéus, for the reason 
that it is an inexact denomination which is moreover applied 
to an idea as vague as incorrect, from the moment that Cumulus 
is not truly rainy as far as it is found displayed, forming a 
stratum as dense in appearance and below a second superior 
stratum of Crvus, equally rainy ; Cwmzlo-stratus, because it 
differs in nothing from Cumulus, according to Howard’s own 
definitions, the three fundamental characters of cloud type and 
of its derivations being common to these two forms, namely : 
their horizontal bases, their superior hemispherical basins, and 
the ascending aggregation of their aqueous particles ; in fine, 
Strato-cumulus (Kaemtz’s cloud of night), because this modifi- 
cation answers in no manner, no more than Howard’s Stva/us 
to clouds of night, and because, on the contrary, its other charac- 
teristics correspond to Cumudo-stratus. ‘ 
On the other hand, I substitute for Mimdbus the Padllium, 
which I sub-divide into Pudlio-cirrus and Paitlio-cumulus, accord- 
ing as its stratum is composed of Cyrus or Cumulus. \ This 
term has the triple advantage of embracing the character, the 
form, and the effect—that is to say, the Cirrus or Cumulus 
forming a rainy stratum. I introduce, in fine, the determi- 
nation of a second transitorial form, which seems to me can be 
rigorously distinguished from the preceding in the double rela- 
tion of cause and effect. This is the Fracto-cumulus fragments 
of clouds which are wandering about without determined form, 
before their transformation into Cumulus (or Cumulo-stratus), 
which are precipitated or detached from the inferior surface of 
the stratum of Sad/io-cumulus, and which, in fine, are spread 
out in horizontal bands at the summit of the Czmzu/us on the 
approach of gusts of wind. These Aracto-cumulus differ from 
the Cumulus in this: they have neither the horizontal base nor 
the superior hemispherical basins while they are not very ex- 
tended ; but as soon as they become a little more increased we 
see at once forming at the centre of the fragment a space more 
dense and blackish than the rest, which gradually settles until it 
constitutes the horizontal base of the Czmzulus (Cumulo-stratus), 
the upper part also becoming rounded by degrees. Thus the 
Fracto-cumulus is the infancy of the Cumulus, otherwise called 
Cumu/lo-stratus, the terms being synonymous. 
This new classification is wholly based upon the zature, the 
form, the quantity, the direction, the velocity, and the azimuthal 
rotation of the clouds corresponding to each stratum fully charac- 
terised by the origin, intimate constitution and meteoric products 
of the vesicular vapours and congealed particles which constitute 
them. For, in the intimate nature of clouds there is one funda- 
mental condition to be established depending upon the physical 
force which first acts upon their constitution ; it is the element of 
heat. Clouds are therefore distinguished into sxow clouds and 
ice clouds, of which the constituent particles are more or less 
congealed ; then into clowds of aqueous vapour, of which the 
vesicles, empty or full, float in a medium above the freezing 
point. 
Under this fundamental aspect there are but two types of clouds 
properly so called, the Cz77ws and the Cumulus. To the Cirrus 
are attached three transitional forms: the Cirro-stratus, Cirro- 
cumulus and Pallio-cirrus ; and to the Cumulus, two other tran- 
sitional forms ; the Padl/io-cumulus and the Fracto-cumulus, 
Here is a table of my new classification of clouds compared 
with that of Howard : 
NEW NOMENCLATURE OF POEY 
First type. Cirrus .. Teclelnide 
Derivative 4 Cirro-Cumulus... Ss Tea 
( Pallio-cirrus...... nom Sues: 
Second type. Cumulus... o Vesicular 
( Pallio-cumulus.... clouds of 
Derivatives 1 
Fracto-cumulus... } aqueous yapour. 
OLD NOMENCLATURE OF HOWARD, 
First type. Cirrus 
Cirro-stratus. 
Cirro-cumulus, 
Second type Cumulus. 
Derivatives—Cumulo-stratus. 
Third type Stratus, 
Derived from the three types—/Vizbus. 
My nomenclature appears probably more in accordance with 
the nature of the clouds in this sense than the two types, Cirrus 
and Cumulus, are rigorously based upon the constitution of ice 
Derivatives | 
