andineus Hail shower.
Cumulo-nimbus Mammatus Festooned shower cloud.
Nimbus Rainfall cloud.
Nimbus nivosus Snowfall.
Nimbus grandineus Hailfall.

IV. _Clouds of Inclination._

Nubes Fulgens Luminous cloud.
Cirrus Curl cloud.
Cirro-filum Gossamer cloud.
Cirro-velum Veil cloud.
Cirro-macula Speckle cloud.
Cirro-velum Mammatum.[1] Draped veil cloud.

It will be seen that Ley's scheme is really an amplification of
Howard's. The term "Interfret" is defined as the interaction of
horizontal currents of different velocities. Inversion is a synonym for
vertical convection, and Inclination is used to imply that such clouds
consist of sloping lines of falling ice particles.

While Ley had been finishing his work and seeing it through the press,
H. Hildebrand-Hildebrandsson and R. Abercromby had devised another
modification which differed from Howard's chiefly by the introduction of
a new class, which they distinguished by the use of the prefix _Alto_.
This scheme was formally adopted by the International Meteorological
Conference held at Munich in 1891, and a committee was appointed to draw
up an atlas showing the exact forms typical of each variety considered.
Finally in August 1894 a small sub-committee consisting of Messrs H.
Hildebrand-Hildebrandsson, A. Riggenbach-Burckhardt and Teisserenc de
Bort was charged with the task of producing the atlas. Their task was
completed in 1896, and meteorologists were at last supplied with a
fairly detailed scheme, and one which was adequately illustrated, so
that there could be no doubt of the authors' meaning. It is as
follows:--

_The International Classification._

(a) Separate or globular masses (most frequently seen in dry weather).

(b) Forms which are widely extended, or completely cover the sky (in wet
weather).

A. _Upper clouds_, average altitude 9000 metres.[2]

a. 1. Cirrus.
b. 2. Cirro-stratus.

B. _Intermediate clouds_, between 3000 m. and 7000 m.

a. 3. Cirro-cumulus.
4. Alto-cumulus.
b. 5. Alto-stratus.

C. _Lower clouds_, 2000 m.

a. 6. Strato-cumulus.
b. 7. Nimbus.

D. _Clouds of Diurnal Ascending Currents._

a. 8. Cumulus, apex 1800 m., base 1400 m.
b. 9. Cumulo-nimbus, apex 3000 m. to 8000 m., base 1400 m.

E. _High Fogs_, under 1000 m.

10. Stratus.

_Explanations._

1. _