Notebook
Cloud genera
Clouds are sorted by height and by whether they heap or spread. These six cover most days; the rest are variations you will recognise once these are familiar.
Low
Cumulus
The cotton-wool cloud of children's drawings: flat base, rounded top, blue sky in between.
Low
Stratus
A featureless grey blanket that hides hill tops and turns the day flat and quiet.
High
Cirrus
Delicate white streaks and hooks of ice, the highest ordinary cloud and the best for sunsets.
Low base, top reaches the stratosphere
Cumulonimbus
A cumulus that kept growing until it became a thunderstorm several kilometres tall.
Middle
Altocumulus
Rows and honeycombs of small rounded patches, white with grey shading, at middle height.
Middle, sometimes high
Lenticular clouds
Smooth lens- or almond-shaped clouds that stand still over hills while the wind blows through them.