When cotton wool attacks . .
The cloud type Cumulonimbus' altitudes can be anywhere from near ground to above 50,000 feet. Since we were flying at 37,000 feet (11,278metres), heading south to Malaysia, the top height of this thunderhead was probably around 39,000 to 40,000 feet.
Cumulonimbus clouds are much larger and more vertically developed than fair weather cumulus. They can exist as individual towers or form a line of towers called a squall line. Fueled by vigorous convective updrafts (sometimes in excess 50 knots), the tops of cumulonimbus clouds can easily reach 50,000 feet (15,000 meters) or higher.
Lower levels of cumulonimbus clouds consist mostly of water droplets while at higher elevations, where temperatures are well below 0 degrees Celsius, ice crystals dominate. Under favorable atmospheric conditions, harmless fair weather cumulus clouds can quickly develop into large cumulonimbus clouds associated with powerful thunderstorms known as supercells.
Cloud Type / Appearance / Altitude
Cumulonimbus / Thunderheads / Near ground to above 50,000 feet
Cirrostratus / Thin, wispy, above thunderheads / Above 18,000 feet
Cirrus / Thin, often with "mare's tail" / Above 18,000 feet
Cirrocumulus / Small puffy clouds / Above 18,000 feet
Altostratus / Thin, uniform, sometimes with "wide wale corduroy" appearance / 6,000 - 20,000 feet
Altocumulus / Medium-sized puffy clouds / 6,000 - 20,000 feet
Stratocumulus / Broad and flat on the bottom, puffy on top / Below 6,000 feet
Cumulus / Puffy clouds / Below 6,000 feet
Stratus / Uniform, thick to thin layered clouds / Below 6,000 feet