Contents:

Low Level Clouds

Middle Level Clouds

High Level Clouds

Do you know your clouds?

Here is a reference for all pilots of what to expect from the weather by looking at the clouds.

These pictures have been referenced to southern hemisphere weather conditions.

LOW LEVEL CLOUDS

CUMULUS humilis Fair weather clouds if they show no vertical development. Vertical development is a good indication for lift.
CUMULUS congestus Can produce showers, usually lead to cumulus nimbus (rain). This is known as OD (over development). If clouds form in the NW to SW there is a likelihood of gusty winds and showers in 5 to 10 hr.
CUMULUS calvus Will produce showers in cold southerly bursts. This is the lead up to thunderstorms. Can become dangerous to pilots due to 'cloud suck'.
STRATOCUMULUS opacus Good indication for worsening conditions and drizzle rain. If found ahead of a cold front, expect strong gusty winds and showers within 5 to 10 hr.
CUMULUS mammatus This pattern looks like inverted mini cumulus clouds, which are caused by turbulent up and down drafts. Definately not ideal flying conditions! Expect heavy showers accompanied by lightning, thunder, strong squalls and if green around leading edges you can expect hail.
Squall Line If you see this coming towards you, I'd recommend you to find a place to land. These clouds are indicators for serve winds, heavy rain showers and even a chance of hail.

MIDDLE LEVEL CLOUDS

ALTOSTRATUS translucidus The sun appears as if viewed through frosted glass. A good indicator for deteriorating conditions with rain likely in 10 to 15 hr , providing there is a steady wind from the NW top S.
ALTOCUMULUS floccus Rain likely in 15 to 20 hr if wind is steady from NW, W to S.
ALTOCUMULUS castellanus Great indicator for the possible thunderstorm development. If you see this in the morning, prepare to be rained apon in the evening.

HIGH LEVEL CLOUDS

CIRRUS fibratus These clouds are formed from ice crystals. They indicate generally fine weather, but rain can be expected within 20 to 30 hr if the wind is from the NW, W to S.
CIRRUS dense These clouds are formed from ice crystals. They usually indicate fine weather, but rain is likely within 20 to 30 hr if the wind is from the NW, W to S.
CIRRUS uncinus These clouds are formed from ice crystals. They predominately indicate fine weather, but rain is likely within 20 to 30 hr if the wind is from the NW, W to S.
CIRROCUMULUS small elements These clouds are formed from ice crystals. Rain is likely within 15 to 20 hr if the wind is from the NW, W to S. Generally fine weather can be expected. If these clouds appear on a summer morning, there is also a chance of thunderstorms in the afternoon.