Cloud PointField Guide

Special cloud — waterfall-made

Cataractagenitus

Cloud born from waterfall spray

Written by Laurence WayneEntry No. 39Rare

Cataractagenitus is a WMO special-cloud name for cloud that develops near large waterfalls, generated when the plunging water is broken up into spray. The downdraught created by the falling water is compensated by locally rising air, which lifts and cools the spray-laden air until cloud forms. The name joins the Latin cataracta (waterfall) and genitus (generated), and is appended to the parent genus — for example Cumulus cataractagenitus.

Worth knowing

  • Cataractagenitus is one of the genuinely new terms added in the 2017 International Cloud Atlas — the atlas's first major revision in roughly 30 years — formally recognising that a big enough waterfall can manufacture its own cloud.
Note

Still unsure it's the same cloud? Our app, Cloud Point— on iOS and Android — reads a photo and returns the likely type with altitude, useful when a formation is fading faster than you can look it up.

Test yourselfThree levels

Choose a difficulty

What produces a cataractagenitus cloud?

  1. aA volcano
  2. bThe spray from a large waterfall
  3. cA forest fire
  4. dA jet engine
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AnswerThe spray from a large waterfall

It develops from water broken into spray by a large waterfall.

The 'genitus' in the name tells you the cloud is named after what?

  1. aIts colour
  2. bIts source — what generated it
  3. cIts height
  4. dIts shape
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AnswerIts source — what generated it

'Genitus' means generated-by; combined with cataracta (waterfall), it marks a cloud made by a waterfall.

In WMO naming, how does a '-genitus' cloud (like cataractagenitus) differ from a '-mutatus' cloud (like homomutatus)?

  1. aThere is no difference; the two endings mean the same thing
  2. b'-genitus' means part of a cloud was generated from a mother cloud or source; '-mutatus' means a cloud has wholly transformed from one genus into another
  3. c'-genitus' clouds are man-made and '-mutatus' clouds are always natural
  4. d'-genitus' means a high cloud and '-mutatus' means a low cloud
Show answer

Answer'-genitus' means part of a cloud was generated from a mother cloud or source; '-mutatus' means a cloud has wholly transformed from one genus into another

The WMO uses '-genitus' for a new genus developing from a part or source of a mother cloud, and '-mutatus' for a cloud that has completely changed from one genus into another.

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