Before 1800, observers spoke of clouds only as essences floating in the sky. Clouds had no names and were not well understood.

Luke Howard noted that there are three basic shapes to clouds: heaps of separated cloud masses with flat bottoms and cauliflower tops, which he named cumulus, Latin for "heap"; layers of clouds which are much wider than they are thick, like a blanket or a mattress, which he named stratus, Latin for "layer"; wispy curls, like a child's hair, which he called cirrus, Latin for "curl". To clouds generating precipitation, he gave the name nimbus, Latin for "rain".