Identifying the types of Cloud present

Determining cloud types at night

The following information may assist with cloud identification at night.

Cloud

With the Moon Present

With the Moon Absent

Cirrus

May be seen against the moon, level of moon light not reduced. Halo (ring around the moon with red on the inside) possible with thick cirrus.

Some stars bright, others hazy; illuminated before sunrise and after sunset and has a reddish glow. Do not confuse hazing of stars with mist or smoke.

Cirrostratus

Milky appearance around moon; possible halo; stars diffused and those near the moon possibly invisible.

All stars more or less dimmed and the outlines diffused.

Cirrocumulus

Thin cloud passing across the moon and not causing any blur of outline.

As for Cirrus.

Altocumulus

Small pieces of cloud passing across moon, but not obscuring it; edges thinner than centre; corona (ring around the moon with red on the outside) may be seen.

Stars blotted out in patches and disappearing and re-appearing regularly.

Altostratus

If thin, moon vaguely visible and remaining uniform as cloud moves; if thick, moon invisible, light rain possible.

If overcast, stars invisible; if broken, some stars visible but no regular appearance and disappearance. If thick and lowering, may be accompanied by rain; this stage will be indicated by preceding observations.

Nimbostratus

Moon invisible. Usually continuous rain.

No stars visible, usually with continuous rain.

Stratocumulus

Moon obscured for intervals.  Thin edges with moon visible through them; sides may be discernible.  Lower surface may be illuminated from below over towns.

As for AC, sometimes (but rarely) precipitation may be noticed. Winds usually light. Over towns/cities the under-surface often illuminated by lights.

Cumulus

Normally easily seen due to distinctive form. May be hard to discern if a layer of SC just above the cumulus cloud fills the intervals between the cumulus. Large Cu may be accompanied by showery precipitation.

Can be difficult to distinguish from AC or broken SC.  Variations in shading from reflected city lights can assist.

Towering Cumulus

Readily seen and distinctive form is visible. May be accompanied by showery precipitation.

As for CU.

Cumulonimbus

Not discernible unless at a distance; may be confused with TCU or layers of AS, unless accompanied by thunder and/or lightning.

As for TCU, except that thunder/lightning/hail may be observed.

Stratus

If thin, moon may be visible; May be discerned as a thin cloud moving rapidly across the moon, usually with cloud above.  Light winds, light drizzle; will reflect the lights of towns. If thick, moon invisible; drizzle, light winds.

If broken, stars are visible. Cannot be distinguished from AS unless accompanied by thick drizzle and light or calm winds; then it must be distinguished from SC. May reflect lights of towns, etc., and appears uniform. Stratus of bad weather is usually indiscernible because of cloud above.