Cumulus clouds are detached, individual, cauliflower-shaped clouds usually spotted in fair weather conditions. The top of these clouds are mostly brilliant white tufts when lit by the sun, although their base is usually relatively dark.
All cumulus clouds develop because of convection. As air heated at the surface is lifted, it cools and water vapour condenses to produce the cloud. Throughout the course of the day, if conditions allow, these can grow in height and size and can eventually form into cumulonimbus clouds.
Along coastlines, cumulus may form over land during daylight hours as a sea breeze brings in moist air, which is then warmed by the surface. This effect reverses overnight as the sea becomes warmer than the land and cumulus form over the sea.
Mostly, cumulus indicates fair weather, often popping up on bright sunny days. Though if conditions allow, cumulus can grow into towering cumulus congestus or cumulonimbus clouds which are capable of producing showers.
Cumulus clouds have four main categorisations or 'species':
info from https://www.metoffice.gov.uk