Cirrus, Stratus, Cumulus

An impressive array of atmospheric events is played out every summer in Montana’s skies.

While cloud-gazing in Big Sky Country, consider the origins of the names of three common cloud types: cirrus, stratus, and cumulus.

In 1803, an English meteorologist named Luke Howard appropriated a trio of Latin terms to classify three fundamental types of clouds. The word cirrus, Latin for “tuft” or “lock of hair,” Howard applied to the wispy filaments of high, delicate clouds.

The meteorologist called flat, layered clouds stratus, from the Latin stratum, or “something laid down.” This cloud term is also related to stratify and stratosphere, the “layer” of the atmosphere above the troposphere.

Clouds of fluffy and billowy appearance, Howard dubbed cumulus. The towering thunderheads filling summer skies are a type of cumulus. Such clouds are notable for their vertical development, reaching 60,000 feet into the heavens.

Luke Howard used the term cumulus in this case because it’s Latin for heap, or pile, suggesting the shape of this type of cloud. Cousins of this word are accumulate, etymologically to collect “heaps” of goods, and cumulative, the outcome of the “heaping” together of many things or events.