Cirrus
High, fine streaks made mostly of ice crystals. They often arrive ahead of a broad weather change.
POCKET GUIDE
Four forms worth knowing.
Cumulus
Detached heaps with flatter bases. Small fair-weather forms may grow when warm air continues rising.
Stratus
A low, uniform layer that can resemble lifted fog. It brings muted light and sometimes drizzle.
Altocumulus
Mid-level patches or rows of rounded cloudlets. Their scale is smaller than low cumulus when seen from the ground.
This is an observation guide, not a forecasting service. Conditions can change quickly.