You are viewing the technical textphoto link on this page

Cumulonimbus Clouds

Cumulonimbus clouds are much larger and more vertically developed than cumulus clouds which form in a more stable atmosphere. They can exist as individual towers or form a line of towers called a squall line often present at cold fronts. Underneath they are dark and menacing. At a distance they rise up like huge white mountains when the Sun shines on them, and are commonly topped with anvil-shaped heads. Fuelled by vigorous convection of air in an unstable atmosphere the tops of cumulonimbus clouds can easily reach 12 km or higher. Lower levels of cumulonimbus clouds consist mostly of water droplets while at higher elevations, where temperatures are well below 0°C, ice crystals dominate.

During the formation of the larger cumulonimbus, condensation droplets are carried up and down several times within the convection currents inside the cloud before being released, coalescing to form raindrops. The more vigorous the thermal currents inside the cloud, the larger the raindrops which form. Light showers can fall form modest-sized "cauliflower" clouds whilst the larger cumulonimbus clouds can produce heavy downpours. The largest cumulonimbus clouds of all are found in thunderstorms. In these clouds up-currents are so severe that splitting of raindrops and ice crystals can occur before re-coalescing and falling to the ground. It is believed that this may contribute to the build up of electric charge and the occurrence of lightning.

Cumulonimbus cloud
 

Weather

Print Topic

Websites
Cumulonimbus
WW2010
PSC Weather Center
Weather Terms

Other topics
Introduction to Weather
Anticyclones
Beaufort Scale
Cirrus Clouds
Clouds
Cold Fronts
Condensation
Convection
Cooling Air
Cumulonimbus Clouds
Cumulus Clouds
Depressions
Dew
Dew Point
Energy
Evaporation
Fog
Forecasting
Fronts
Frost
Humidity
Hurricanes
Isobars
Measuring Weather
Meteorology
Monsoons
Movement of Air
Occluded Fronts
Precipitation
Pressure
Sea Breeze
Stability of Air
Stratus Clouds
Sunshine
Synoptic Charts
Temperature
Thunderstorms
Tornadoes
Uplift of Air
Warm Fronts
Water Cycle
Weather Symbols
Wind

Home