Scaffolded notes
Build the idea
Cloud names describe form and height
Cumulus clouds are puffy and linked to rising parcels. Stratus clouds form broad layers. Cirrus clouds are high and icy. Prefixes add clues: alto indicates middle levels, nimbo or nimbus indicates precipitation, and cumulo indicates vertical development.
Droplets must grow
Cloud droplets are usually too small to fall as precipitation. In warmer clouds, droplets collide and combine through coalescence. In cold clouds, ice crystals can grow while nearby droplets evaporate. Falling particles may melt, freeze, or remain frozen depending on the temperature profile.
Clouds are forecast evidence
Fair-weather cumulus may indicate limited convection. Growing towering cumulus can warn of increasing instability. Cumulonimbus clouds can produce heavy rain, lightning, hail, strong winds, and sometimes tornadoes. Layered clouds commonly accompany gradual lifting near warm fronts.
Stop and explain
Check your thinking
1. Which cloud shows the greatest vertical development?
Possible response: Cumulonimbus.
2. Why can a cloud exist without precipitation reaching the ground?
Possible response: Droplets may be too small or falling precipitation may evaporate before reaching the surface.
Interactive challenge
Try the science
Match the cloud to the strongest clue.
Before you leave
Exit ticket
What cloud change would make you more concerned about thunderstorms?