Cabbage Tree Weather · Toko Mouth, Otago

Reading the Sky:
A Field Guide to Clouds

Every cloud tells a story — learn to read the atmosphere above you, from wispy cirrus at 12 kilometres down to the storm-dark wall of a cumulonimbus.

☁ Cloud altitude tiers · Southern Hemisphere mid-latitudes
6 – 12+ km
High clouds
2 – 6 km
Mid clouds
0 – 2 km
Low clouds
Surface–12 km
Vertical



6 – 12 km

High Clouds

CirrusCi
6,000 – 12,000 m

Thin, wispy filaments drawn across an otherwise blue sky — ice crystals swept by jet-stream winds into mare’s tails and hooks. The first sign weather is on the move.

⇢ Fair, change coming


CirrocumulusCc
6,000 – 12,000 m

A delicate rippled sheet of tiny white puffs — the classic “mackerel sky.” Each cell is made of supercooled water droplets, no bigger than a finger held at arm’s length.

⇢ Mackerel sky


CirrostratusCs
6,000 – 12,000 m

A translucent ice-crystal veil that dims the sun or moon and produces halos — luminous rings of 22°. The sky looks milky. Rain is usually 12–24 hours away.

⇢ Rain in 12–24 h



2 – 6 km

Mid Clouds

AltocumulusAc
2,000 – 6,000 m

Grey-and-white patchy rolls arranged in rows or waves. Larger than cirrocumulus cells, they cast shadows on each other. Morning altocumulus can precede afternoon thunderstorms.

⇢ Possible storms


AltostratusAs
2,000 – 6,000 m

A featureless grey or blue-grey sheet covering the whole sky. The sun appears as though seen through frosted glass — no halo is possible. Prolonged rain or snow likely.

⇢ Persistent rain



0 – 2 km

Low Clouds

StratusSt
0 – 500 m

The low, grey blanket that hugs hillsides and coastlines — indistinguishable from fog when it touches the ground. Produces drizzle rather than rain. Otago’s southerly specialist.

⇢ Drizzle, murk


StratocumulusSc
500 – 2,000 m

The most common cloud on Earth. Grey-white lumpy rolls or patches with clear gaps between groups. Rarely produces significant rain, but can thicken into nimbostratus.

⇢ Mostly harmless


NimbostratusNs
500 – 3,000 m

Dark, formless, and merciless. A thick rain-producing sheet that obliterates the sun and delivers steady, continuous precipitation — rain, snow, or sleet — often for many hours.

⇢ Continuous rain/snow



Surface – 12 km

Vertical Clouds

CumulusCu
500 – 2,000 m base

The classic white cauliflower cloud of a fine day. Flat base, dome-shaped top, sharp edges. Formed by rising thermals. Fair-weather cumulus stay modest; those that keep growing become cumulonimbus.

⇢ Fine, watch for growth


CumulonimbusCb
500 m – 12 km+

The king of clouds. A towering colossus spanning the full depth of the troposphere, its top sheared into an ice-crystal anvil by the jet stream. Produces lightning, heavy rain, hail, and tornadoes.

⇢ Severe weather

Lenticular Clouds — New Zealand’s Mountain Saucers

When stable air flows over the Southern Alps or Otago ranges, it oscillates in standing waves downwind. Moisture condenses at the crest of each wave, forming smooth, lens-shaped clouds — lenticulars — that hover motionless above peaks while air streams through them. They’re not UFOs. They are, however, one of the most dramatic sights in the South Island sky and a reliable signal of high winds aloft.

Fieldcraft

Reading Clouds in the Field

🌅
Watch the morning sky

High thin cloud at dawn thickening through the day is a reliable sequence toward afternoon rain. Altocumulus at sunrise often precedes convective storms by mid-afternoon.

📐
Use your fist

Hold your fist at arm’s length. Cumulus smaller than a fist are fair-weather. Taller than your fist, they’re growing. Taller than two fists, seek shelter.

💫
The halo rule

A 22° halo around the sun or moon means cirrostratus overhead — ice crystals refracting light. Rain within 12–24 hours is a strong probability.

🌊
Coastal clues

At Toko Mouth, sea-breeze convergence can build coastal cumulus rapidly in late afternoon even on otherwise fine days. Watch for towers appearing over the Tokomairiro lowlands.

Summary

Quick Reference

Cloud	Abbr.	Altitude	Likely weather
Cirrus	Ci	6–12 km	Fair; change in 24–48 h
Cirrocumulus	Cc	6–12 km	Fair, unsettled
Cirrostratus	Cs	6–12 km	Rain/snow in 12–24 h
Altocumulus	Ac	2–6 km	Possible storms (morning)
Altostratus	As	2–6 km	Persistent rain or snow
Stratus	St	0–500 m	Drizzle, fog
Stratocumulus	Sc	500–2,000 m	Little/no rain
Nimbostratus	Ns	500–3,000 m	Continuous rain/snow
Cumulus	Cu	500–2,000 m base	Fair; watch for growth
Cumulonimbus	Cb	500 m – 12 km+	Thunderstorms, hail, severe