We see clouds almost every day, yet we haven’t seen most of them in our lives. These beautiful masses of droplets may seem random, however there’s a whole cloud classification system uniform worldwide that was introduced back 1802 by Luke Howard.

Howard named the three principal categories of clouds – cumulus, stratus, and cirrus, as well as a series of intermediate and compound modifications, such as cirrostratus and stratocumulus, in order to accommodate the transitions occurring between the forms. He also identified the importance of clouds in meteorology: “Clouds are subject to certain distinct modifications, produced by the general causes which affect all the variations of the atmosphere; they are commonly as good visible indicators of the operation of these causes, as is the countenance of the state of a person’s mind or body.”

Here’s a selection of some of the most impressive cloud formations ever captured – have you ever seen any similar ones yourself?

Mammatus Clouds

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Image credits: HeavyLight.ca

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Image credits: Ken Lewis -

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Image credits: Vincent Fryhover

Lenticular Clouds

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Image credits: Brian Middleton

Image credits: Jean-Michel Priaux

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Image credits: Dementievskiy Ivan

Undulatus Asperatus

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Image credits: JΩSH

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Image credits: wittap

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Image credits: JΩSH

Fallstreak Hole

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Image credits: ladigue_99

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Image credits: mtnrockdhh

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Image credits: lookseenseen

Polar Stratospheric Cloud

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Image credits: Alan R. Light

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Image credits: FotoLind

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Image credits: FotoLind

Cirrus Kelvin-Helmholtz

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Image credits: drdouglascordeiro.blogspot.com

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Image credits: drdouglascordeiro.blogspot.com

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Image credits: pfjc&pfjc2

Roll Clouds

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Image credits: Kick Petroff

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Image credits: apod.nasa.gov

Anvil Clouds

Image credits: Nicholas_T

Image credits: hide

Image credits: *Lampy*

Also, check out Smeared Sky Photography by Matt Molloy